2012 Purdue University Turfgrass Research Summary Research Summary. ... (Taraxacum officinal) and wild violet (viola spp). Photo by Aaron Patton. ... selected candidate genes to specific

2012 Purdue University Turfgrass Research Summary

AcknowledgementsThis publication was designed and prepared by Jennifer Biehl, Event and Program Coordinator for the Purdue Turf Science Program and Midwest Regional Turf Foundation.

DisclaimerSome of the information presented in this guide, especially pesticide recommendations, may be specific to Indiana. Readers outside Indiana should check with their own cooperative extension services for state-specific information. Reference in this publication to any specific commercial product, process, or service, or the use of any trade, firm, or corporation name is for general informational purposes only and does not constitute an endorsement, recommendation, or certification of any kind by Purdue University. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.

On the cover: Dandelion (Taraxacum officinal) and wild violet (viola spp). Photo by Aaron Patton.

2012 Purdue University Turfgrass Research Summary

Table of Contents PageLetter from Purdue Turf Program Faculty ..............................................................................................................iSupporters of the Purdue University Turf Program in 2012 ........................................................................ ii

Turf ManagementAssociation of Candidate Genes with Drought Tolerance Traits in Diverse Perennial Ryegrass

Accessions .................................................................................................................................................................... 1

Growth and Physiological Responses of Diverse Perennial Ryegrass Accessions to Increasing Salinity ........................................................................................................................................................................... 7

Weed Management

Efficacy of Methiozolin for Controlling Annual Bluegrass in a Creeping Bentgrass Golf Course Putting Green............................................................................................................................................................12

Dandelion Control and Flower Suppression with Defendor Herbicide ..................................................15Herbicide Selection and Timing Influences Ground Ivy Control – 2012 Results ...............................20Selecting Turfgrasses and Mowing Strategies to Reduce Mowing Requirements .............................27Controlling Poa annua on putting green height turf in Indiana, Michigan, and

Nebraska: 2012 Research Update ...................................................................................................................32Postemergence Broadleaf Herbicide Safety on Creeping Bentgrass

Putting Greens – 2012 Update ..........................................................................................................................35Evaluation of Crabgrass Control with Various Preemergence Herbicides - 2012 .............................39Herbicide Efficacy on Wild Violet – Greenhouse Experiments ..................................................................42Insect ManagementInfluence of Application Rate on the Efficacy of Acelepryn Against Bluegrass

Billbug in Kentucky Bluegrass Turf 2012 ....................................................................................................48Residual Activity of Meridian 25WG and Two Rates of Acelepryn 1.67SC Against

Second and Third Instar Black Cutworm Larvae on Creeping Bentgrass Turf ............................50Influence of Application Timing on the Efficacy of Acelepryn and Merit Against

Japanese Beetle Larvae in Kentucky bluegrass turf .................................................................................52

Efficacy of Single vs. Split-Application of QualiPro Imidacloprid, Aloft and Allectus Against Japanese Beetle Larvae in Kentucky Bluegrass Turf 2012 .................................54

Disease ManagementIntegrating fungicide and genetic host resistance for control of dollar spot on

creeping bentgrass. ................................................................................................................................................56Evaluation of Velista (penthiopyrad) for Control of Brown Patch and Dollar

Spot on Creeping Bentgrass, 2012 ..................................................................................................................59

Turfgrass Industry:

As the green industry continues to have a large impact on Indiana and the nation, Purdue University has assembled an outstanding team of researchers, extension personnel, and educators that are dedicated to solving problems and helping meet the needs of Indiana residents. One segment of the Indiana green industry that continues to provide a significant impact on the state’s economy is the turfgrass industry, which includes residential and commercial lawn care, sports turf, cemeteries, sod production, golf course maintenance, and more. Indiana’s professional turfgrass industry is estimated by some to generate in excess of $1.4 billion in annual expenditures and provide over 11,500 jobs.

The Annual Report of the Purdue University Turf Program is published each year by the Purdue Turf Team and features significant findings made by turfgrass scientists over the past year. It is our desire that this publication will keep our stakeholders up-to-date on significant changes and advancements that affect our industry.

This 2012 Annual Report includes 16 papers from faculty, staff, and graduate students. We hope that these findings will enhance your ability to conduct business in an efficient and productive manner.

We would also like to recognize the many organizations, companies, and individuals who have contributed their time, talent and resources to help make our program successful. We are forever indebted to the many people who contribute to this program. Special recognition goes to the Midwest Regional Turf Foundation which supports the research and extension programs of each member of the Turf Team and also provides substantial support towards the operating and capital expenses of the W.H. Daniel Turfgrass Research and Diagnostic Center.

We hope that this publication will be of value to all persons with an interest in the Indiana green industry.

Cale BigelowAssociate Professor

Tim GibbInsect Diagnostician

Yiwei JiangAssociate Professor

Rick LatinProfessor

Doug RichmondAssociate Professor

Aaron PattonAssistant Professor

i

Supporters of the Purdue University Turf Program in 2012The Turfgrass Program at Purdue University relies on the support of the Midwest Regional Turf Foundation and gifts from the turfgrass industry for a large portion of its operating budget. We would like to extend our thanks to the members of the Midwest Regional Turf Foundation for their loyal support of turfgrass research and education at Purdue.In addition, various individuals, organizations, and businesses have provided grants, products, or equipment to support our efforts throughout the year. Without this support, we would be unable to conduct many of the research projects included in this report.

IndividualsAl Capitos, Purdue Univ. Athletic Dept.Greg Shaffer, Elcona Country ClubJim Scott, Purdue Univ. Athletic Dept.Brian Bornino, Purdue Univ. Athletic Dept.Scott Helkamp, Purdue Univ. Grounds Dept

We regret that some individuals or companies may have inadvertently been left off of this list. If your company has provided financial or material support for the program and is not mentioned above, please contact us so that your company's name can be added in future reports.

Companies/OrganizationsThe Andersons, Inc.Arysta LifeScienceAquatrolsBASF CorporationBayer Environmental ScienceBecker UnderwoodCISCO SeedsCLC LabsDow AgroSciencesDuPont Professional ProductsElcona Country ClubFloratineFMC Corporation Golf Course Superintendents Assoc. of AmericaGowan CompanyHamlet Golf CourseHenderson Country ClubHoosier Golf Course Superintendents Assoc.Indiana Seed SolutionsIndiana Golf Course Superintendents AssocJohn Deere LandscapesKenney Outdoor SolutionsKentuckiana Golf Course Superintendents Assoc.Knox Fertilizer Co.Lastec

L.T. Rich Products, Inc.Marrone BioMichiana Golf Course Superintendents Assoc.Midwest Regional Turf FoundationMonsanto, Inc.National Turfgrass Evaluation Program (NTEP)NuFarm Americas IncPBI GordonPermaGreen Supreme, Inc.Phoenix Environmental CarePrecision LaboratoriesPurdue Pesticide ProgramsQuali-ProScott’s Company, TheSeed Research of OregonSeProSyngenta Crop ProtectionTenbarge Seed CompanyTri-State Golf Course Superintendents Assoc.Turfgrass, Inc/ResidexUnited States Department of Agriculture NC-RIPMUnited States Golf AssociationValent USA

ii

Xiaoqing Yu and Yiwei Jiang, Department of Agronomy, Purdue University

Yu, X., and Y. Jiang. 2013. Association of Candidate Genes with Drought Tolerance Traits in Diverse Perennial Rye-grass Accessions. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 1-6.

Summary: Plant drought tolerance is a complex trait that is controlled by multiple genes. Candidate gene association mapping provides a powerful tool for dissection of complex traits. We conducted candidate gene-association mapping of drought tolerance traits in 192 diverse perennial ryegrass (Lolium perenne L.) accessions from 43 countries. A total of 346 single nucleotide polymorphisms were identified from genes involved in antioxidant metabolism, dehydration, and water movement across membrane and signal transduction. Significant associations were identified between a putative LpLEA3 encoding late embryogenesis abundant group 3 protein and a putative LpFeSOD encoding iron superoxide dismutase and leaf water content, as well as between a putative LpCyt Cu-ZnSOD encoding cytosolic copper-zinc superoxide dismutase and chlorophyll fluorescence under drought conditions. These results indicate that allelic variation in these genes may affect whole-plant response to drought stress in perennial ryegrass.

Additional index words: LpCyt Cu-ZnSOD, LpFeSOD, LpLEA3, Lolium perenne

depending on population size and individual genes (Skøt et al., 2007; Xing et al., 2007; Brazauskas et al., 2011; Fiil et al., 2011). A candidate gene, FLOWERING LOCUS T, has been found to be associated with changes in flowering time across a range of populations of perennial ryegrass (Skøt et al., 2011). In maize (Zea mays L.), candidate-gene association mapping identified single nucleotide polymorphisms (SNPs) in genes that affect abscisic acid levels in floral tissue during drought stress (Setter et al., 2011). These findings indicate that the candidate gene-association mapping approach can be effectively used to establish associations between targeted genes with known function and complex traits in out-crossing species.

Perennial ryegrass (Lolium perenne L.) is a cool-season perennial grass species from the family Poaceae. Perennial ryegrass is a self-incompatible diploid (2n = 2x =14) out-crossing species (Cornish et al., 1980). Among the major perennial grass species, perennial ryegrass is a good model for studying association of gene and drought tolerance because of its diploid genetics, available genetic and genomics resources, rapid stress responses, and available germplasm collections. Knowledge gained from studying this species will facilitate further investigation in other perennial grass species with more complex, polyploid genomes.

TURFGRASS SCIENCE

Association of Candidate Genes with Drought Tolerance Traits in Diverse

Perennial Ryegrass Accessions

Linkage disequilibrium (LD)-based association mapping is a powerful tool for genetically dissecting complex traits controlled by multiple quantitative trait loci (QTLs) in crop species (Yu et al., 2006; Harjes et al., 2008; Tian et al., 2009; Li et al., 2011; Skøt et al., 2011; Cook et al., 2012). Through exploitation of historical recombination events at a population level, association studies identify marker-trait associations and test large numbers of alleles in a diverse population (Yu and Buckler, 2006). For a species in which LD decays rapidly, candidate-gene association mapping is appropriate to relates sequence variations in selected candidate genes to specific traits of interest (Zhu et al., 2008). Rapid LD decay within 300 to 2000 bp has been detected in perennial ryegrass,

1

Purdue Turfgrass Science Program 2012 Annual Report

The objective of this study was to conduct candidate gene association mapping of drought tolerance in perennial ryegrass. We hypothesized that diverse perennial ryegrass varied largely in whole-plant physiological traits related to drought tolerance. Given the evidence that genes involved in antioxidant pathways and in other functional or regulatory systems may play a role in drought tolerance, we also hypothesized that these candidate genes were significantly associated with drought tolerance traits in perennial ryegrass.

Materials and MethodsA global collection of 186 perennial ryegrass accessions was obtained from the USDA National Plant Germplasm System at the Western Regional Plant Introduction Station in Pullman, WA, USA and six turf-type commercial cultivars were obtained from the seed industry (Turf-Seed Company, Gervais, OR, USA; Scotts Inc., Marysville, OH, USA). This collection was based on geographical locations of accessions to maximize ecotype diversity. The panel included 72 wild, 66 cultivated, and 54 accessions with uncertain pedigree according to germplasm bank classification. All the accessions were confirmed as diploid by flow cytometry (Wang et al., 2009a). A single seed from each accession was initially sown in small plastic pots containing a sandy-loam soil with a pH of 6.9. Each accession was then propagated multiple times by tillers to maintain genetic uniformity. The grasses were planted in the field in Wanatah, West Lafayette, and Vincennes in Indiana in August 2008, respectively. Soil type was sandy loam in Wanatah and Vincennes and silt loam in West Lafayette. Each location had three replications for each accession with the same genotypes across locations. A total of 179 accessions were alive after winter 2008 and were used for phenotypic data collection. Drought stress was imposed in the plots by withholding water for 7 to 10 days after initial measurements were taken under well-watered conditions in May at each location in 2009 and 2010. All accessions were under drought stress for the same amount of time. The typical climatic pattern at the field site included multiple dry spells each lasting 7 to 15 days during the growing season, which caused light to severe leaf wilting in the perennial ryegrass accessions.

Data were collected before and after drought stress at three locations in 2009 and 2010 for the following traits: canopy and air temperature difference (CAD), leaf water content (LWC), chlorophyll fluorescence (Fv/Fm), and leaf wilting. Leaf wilting was assessed by visual rates using 1 (slightly wilting) to 9 (severe wilting) scale. CAD, LWC, and Fv/Fm were measured under both well-watered and drought stressed conditions, while leaf wilting was only assessed under drought stress.

A total of 109 simple sequence repeat (SSR) markers developed in perennial ryegrasses were used to screen the mapping population and obtain genetic relationship among accessions. Population structure was determined by model-based clustering using STRUCTURE 2.3.1 (Pritchard et al., 2000) and relative pairwise kinship was calculated using SPAGeDi (Hardy and Vekemans, 2002) with all 109 polymorphic SSR markers. Fourteen candidate genes were selected for sequencing, including 10 putative genes encoding antioxidant enzymes and additional putative genes of LEA encoding late embryogenesis abundant protein, PIP, TIP, and MAPK encoding mitogen activated protein kinase. Both genomic DNA and reverse-transcript cDNA were used as PCR amplification template for synthesis and sequencing of these genes. Sequencing was conducted using an ABI 3730 genetic analyzer according to the manufacturer’s instructions (Applied Biosystems, Carlsbad, CA, USA) in the Genomic Center at Purdue University. Diploid SNP were identified using the NovoSNP program 3.0.1 Microsoft Windows Platform version (Weckx et al., 2005). Rare SNP was excluded for SNP counting when the total non-major allele counting < 5% (~ eight accessions in this population). The LD was calculated for each candidate gene using TASSEL 2.1 (Bradbury et al., 2007).

Results and DiscussionAccessions differed significantly in CAD, Fv/Fm, LWC, and leaf wilting (Table 1). Among all accessions across six environments, CAD ranged from -2.67 °C to 2.08 °C, Fv/Fm ranged from 0.75 to 0.83, and LWC ranged from 2.76 (g/g) to 6.17 (g/g) under well-watered conditions (Table 1). Under drought conditions, the minimum and maximum values were 0.53 °C and 6.53 °C for CAD, 0.71 and 0.84 for Fv/Fm, 1.80 (g/g) and 3.93 (g/g) for LWC,

2


and 2.7 to 8.0 for leaf wilting, respectively (Table 1). Leaf wilting, CAD, Fv/Fm, and LWC provide rapid and easy measurements for whole-plant responses, thus, they have been used to screen drought tolerant plant materials and characterize drought tolerance at the whole-plant level (O’Neill et al., 2006; Jiang et al., 2009; Luo et al., 2011). In this study, leaf wilting and other drought response traits were studied in perennial ryegrasses exposed to 7 to 10 days of drought stress, however, stress could last longer than this duration in some areas where perennial ryegrass are grown, which may further affect phenotypic trait variation in germplasm. The potential variability in short-term vs. long term drought response should be taken into consideration when developing perennial grasses for improved drought tolerance.

The STRUCTURE analysis identified five groups (G1, G2, G3, G4, and G5) in this panel of perennial ryegrass (Fig. 1) based on likelihood plots of the models, stability of grouping patterns across different runs, and germplasm information (Wang et al., 2009b). G1 was the largest and most diverse group, with 121 accessions of mixed origins, including all the accessions from Oceania and the majority of the accessions from the U.S., Canada, Europe, and South America. Approximately 89.4 % of cultivated materials were assigned into G1 including 10 out of 11 turfgrass cultivars. Further distinct subgroups were not detected within G1 after independent structure analysis (data not shown). G2 contained 21 accessions; from Europe

(14), Asia (6), and one turf-type commercial cultivar from USA. G3 was the second largest group, with 25 accessions; mainly from Europe (13), Africa (7), and Asia (3). G4 contained 13 accessions, mainly from North Africa (Algeria, Morocco, and Tunisia). G5 was the smallest with 12 accessions mainly from Southern Europe and Asia. There was no obvious kinship in this population. More than 55 % of the pairwise kinship estimates were zero while about 35 % were between zero to 0.05, indicating 90 % of estimates were less than 0.05.

Combined LD analysis of 13 genes (LpAPX was dropped because of many uncertain SNPs) showed LD decay close to 0.1 in less than 1 kb (Fig. 2). This was similar to the average frequency of one SNP per 24 to 33 bp for 11 disease resistance candidate genes in Lolium perenne (Xing et al., 2007), but higher than one SNP every 94 bp in five genes for shoot morphology in perennial ryegrass (Brazauskas et al., 2011) and one SNP per 127 bp in nine genes for flowering time in 20 genotypes of perennial ryegrass (Fiil et al., 2011). By implementing population structure (Q) based model, three SNPs at loci 134, 220, and 287 from LpCyt Cu-ZnSOD, one at locus 411 from LpFeSOD and two at loci 237 and 285 from LpLEA3 were significantly associated with Fv/Fm, LWC and LWC under drought stress, respectively with P value ranging from 9.02 × 10-5 to 4.94 × 10-4 (Table 2). Compared to the simple linear model, this was an elimination of approximately 70%

Table 1. Range of canopy and air temperature difference (CAD), leaf water content (LWC) chlorophyll fluorescence (Fv/Fm), and wilting for 179 diverse perennial ryegrass accessions under control (C) and drought (D) conditions

CAD (°C) Fv/Fm LWC (g/g) Wilting C D C D C D D

Minimum -2.67 a 0.53 0.746 0.707 2.76 1.80 2.7 Maximum 2.08 6.53 0.826 0.836 6.17 3.93 8.0 Mean -1.08 2.75 0.808 0.798 4.18 2.57 4.6 Std b 0.92 0.99 0.010 0.016 0.53 0.32 0.94

a Data summarized across three locations for year 2009 and 2010.

b Standard deviation

3


Figure 1. Genetic relatedness of 192 perennial ryegrass accessions with 109 simple sequence repeat (SSR) as analyzed by the STRUCTURE program. Numbers on the y-axis indicate the membership coef-ficient. The color of the bar indicates the five groups identified through the STRUCTURE program (G1 = red, G2 = green, G3 = blue, G4 = yellow, and G5 = pink). Accessions with the same color belong to the same group.

false positive correlations under drought stress. R2 marker values ranged from 0.075 to 0.097 among all those associated SNPs. On average, each marker explained 8.9% (± 0.8%) of phenotypic variance for its associated trait (Table 2). The advantage allele from LpLEA3 and LpCyt Cu-ZnSOD discovered in this study could be considered as target candidate for gene transformation and for further developing markers for breeding program to improve drought tolerance of perennial ryegrass and other polyploid perennial grasses. Our study provided valuable information to candidate gene-based association mapping of drought tolerance in highly heterozygous perennial grasses.

Acknowledgements This project is supported by the Midwest Regional Turfgrass Foundation of Purdue University, The O.J. Noer Research Foundation, United State Golf Association, Mary S. Rice Farm Grant, and Purdue University Research Foundation.

ReferencesBradbury, P.J., Z. Zhang, D. E. Kroon, T. M. Casstevens, Y. Ramdoss, and E. S. Buckler. 2007. TASSEL: software for association mapping of complex traits in diverse samples. Bioinformatics 23: 2633-2635.

Brazauskas, G., I. Pasakinskiene, T. Asp, and T. Lubberstedt. 2011. Nucleotide diversity and linkage disequilibrium in five Lolium perenne genes with putative role in shoot morphology. Plant Sci. 179: 194-201.

4


Table 2. Association of candidate genes with traits of perennialryegrass assessed by using population structure controlled model(Q model). Trait Putative Gene Locus R2_Marker p_MarkerD-Fv/Fm LpCyt Cu-ZnSOD 134 0.0969 9.02E-05 D-Fv/Fm LpCyt Cu-ZnSOD 220 0.0828 2.48E-04 D-Fv/Fm LpCyt Cu-ZnSOD 287 0.0752 4.94E-04 D-LWC LpLEA3 285 0.0905 3.92E-04 D-LWC LpLEA3 237 0.0914 3.63E-04 D-LWC LpFeSOD 411 0.0945 2.63E-04

D-Fv/Fm, chlorophyll Fluorescence under drought condition.

D-LWC, leaf water content under drought condition.

Figure 2. Linkage Disequilibrium (LD) decay in perennial ryegrass. Plots of squared correlations of allele frequencies (r2) against physical distance between pairs of SNPs in the pooled 13 genes.

0

0.2

0.4

0.6

0.8

1

0 200 400 600 800 1000

r2

Distance (bp)

r^2

Log. (r^2)

5


References Cont.Cook, J.P., M.D. McMullen, J.B. Holland, F. Tian, P. Bradbury, J. Ross-Ibarra, E.S. Buckler, and S.A. Flint-Garcia. 2012. Genetic architecture of maize kernel composition in the nested association mapping and inbred association panels. Plant Physiol. 158: 824-834.

Cornish, M.A., H.D., Hayward, and M.J. Lawrence. 1980. Self-incompatibility in ryegrass. I. Genetic control in diploid Lolium perenne L. Heredity 43: 95-106.

Fiil, A., I. Lenk, K. Petersen, C.S. Jensen, K.K. Nielsen, B. Schejbel, J.R. Andersen, and T. Lubberstedt . 2011. Nucleotide diversity and linkage disequilibrium of nine genes with putative effects on flowering time in perennial ryegrass (Lolium perenne L.). Plant Sci. 180: 228-237.

Hardy, O.J., and X. Vekemans. 2002. SPAGeDi: a versatile computer program to analyze spatial genetic structure at the individual or population levels. Mol. Eco. Notes 2: 618-620.

Harjes, C.E., T.R. Rocheford, L. Bai, T.P. Brutnell, C.B. Kandianis, S.G. Sowinski, A.E. Stapleton, R. Vallabhaneni, M. Williams, E.T. Wurtzel, J. Yan, and E.S. Buckler. 2008. Natural genetic variation in Lycopene Epsilon Cyclase tapped for maize biofortification. Science 319: 330-333.

Jiang,Y., H. Liu, and V. Cline. 2009. Correlations of leaf relative water content, canopy temperature, and spectral reflectance in perennial ryegrass under water deficit conditions. HortScience 44:459-462.

Li, Y., A. Bock, G. Haseneyer, V. Korzun, P. Wilde, C.C. Schon, D,P. Ankerst, and E. Bauer. 2011. Association analysis of frost tolerance in rye using candidate genes and phenotypic data from controlled, semi-controlled, and field phenotyping platforms. BMC Plant Biol. 11: 146.

Luo, N., J. Liu, X. Yu, and Y. Jiang Y. 2011. Natural variation of drought response in Brachypodium distachyon. Physiol. Plant. 141: 19-29.

O’Neill, P.M., J.F. Shanahan, and J.S. Schepers. 2006. Use of chlorophyll fluorescence assessments to differentiate corn hybrid response to variable water conditions. Crop Sci. 46: 681-687.

Pritchard, J.K., M. Stephens, and P. Donnelly. 2000. Inference of population structure using multilocus genotype data. Genetics. 155: 945-959.

Setter, T.L., J. Yan, M. Warburton, J.M. Ribaut, Y. Xu, M. Sawkins, E.S. Buckler, Z. Zhang, and M.A. Gore. 2011. Genetic association mapping identifies single nucleotide polymorphisms in genes that affect abscisic acid levels in maize floral tissues during drought. J. Exp. Bot. 62: 701-716.

Skøt, L., J., Humphreys, M.O. Humphreys, D. Thorogood, J. Gallagher, R. Sanderson, I.P. Armstead, I.P. and I.D. Thomas. 2007. Association of candidate genes with flowering time and water-soluble carbohydrate content in Lolium perenne (L.). Genetics 177: 535-547.

Skøt, L., R. Sanderson, A. Thomas, K. Skot, D. Thorogood, G. Latypova, T. Asp, and I. Armstead. 2011. Allelic variation in the perennial ryegrass FLOWERING LOCUS T gene is associated with changes in flowering time across a range of populations. Plant Physiol. 155: 1013-1022.

Tian, Z., Q. Qian, Q. Liu, M. Yan, X. Liu., C. Yan, G. Liu, Z. Gao, S. Tang, D. Zeng, Y. Wang, J, Yu, M. Gu, and J. Li. 2009. Allelic diversities in rice starch biosynthesis lead to a diverse array of rice eating and cooking qualities. Proc. Natl. Acad. Sci. U.S.A. 106: 21760-21765.

Wang, M., C. Zhu, N. Barkley, Z. Chen , J. Erpelding, M.S, Tuinstra, T. Tesso, G. Pederson, and J. Yu. 2009b. Genetic diversity and population structure analysis of accessions in the US historic sweet sorghum collection. Theor. Appl. Genet. 120: 13-23.

Wang, Y., C.A. Bigelow, and Y. Jiang. 2009a. Ploidy level and DNA content of perennial ryegrass germplasm as determined by flow cytometry. HortScience 44: 2049-2052.

Weckx, S., J. Del-Favero, R. Rademakers, L. Claes, M. Cruts, P. DeJonghe, C. Van Broeckhoven, and P. DeRijk. 2005. NOVO SNP, a novel computational tool for sequence variation discovery. Genome Res. 15: 436-442.

Xing, Y., U. Frei, B. Schejbel, T. Asp, and T. Lübberstedt. 2007. Nucleotide diversity and linkage disequilibrium in 11 expressed resistance candidate genes in Lolium perenne, BMC Plant Biol. 7: 43.

Yu, J., G. Pressoir, W.H. Briggs, B.I. Vroh, M. Yamasaki, J.F. Doebley, M.D. McMullen, B.S. Gaut, D. Nielsen, J.B. Holland, S. Kresovich, and E.S. Buckler. 2006. A unified mixed-model method for association mapping that accounts for multiple levels of relatedness. Nat. Genet. 38:203-208.

Yu, J.M. and E.S. Buckler. 2006. Genetic association mapping and genome organization of maize. Curr. Opin. Biotech. 17: 155-160.

Zhu, C., M. Gore, E.S. Buckler, and J. Yu. 2008. Status and prospects of association mapping in plants. The Plant Genome 1: 5-20.

6

Yiwei Jiang1, Jinchi Tang2, Xiaoqing Yu1 and James J. Camberato1. 1Department of Agronomy, Purdue University. 2 Guangdong Academy of Agricultural Science, Guangzhou, China.

Jiang, Y., J. Tang, X. Yu and J. Camberato. 2013. Growth and Physiological Responses of Diverse Perennial Ryegrass Accessions to Increasing Salinity. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 7-11.

Summary: Ten diverse accessions of perennial ryegrass (Lolium perenne L.) were grown in sand culture and exposed to a half-Hoagland solution amended with 0 (control), 50-, 100-, 150-, 200-, and 300 mM NaCl. Across all accessions, decreased plant height, K+ concentration and K+/Na+ and increased concentrations of fructan and Na+ were observed at ≥ 50 mM NaCl, while decreased leaf fresh and dry weight (DW), leaf water content (LWC), chlorophyll fluorescence (Fv/Fm), and increased water-soluble carbohydrate concentration (WSC) occurred at ≥ 150 mM NaCl. The maximum separations of salinity tolerance of accessions occurred at 200 to 300 mM NaCl. The results indicated that DW, LWC, Fv/Fm and Na+ could be associated with variability in tolerance of diverse perennial ryegrasses to high salinity stress.

Additional index words: Carbohydrate, ion accumulation, Lolium perenne, salt stress

L.), hybridbermuda grass (Cynodon dactylon x. Cynodon transvaalensis.) and serangoon grass (Digitaria didactyla Willd.), although inhibition of growth occurred in all species exposed to salinity (Uddin et al., 2012).

Turfgrasses are increasingly subjected to salinity stresses in many areas due to the accelerated salinization of agricultural lands and increasing demand on effluent water use for irrigating turfgrass landscapes (Carrow and Duncan, 1998). Perennial ryegrass (Lolium perenne L.) is a popular cool-season grass species cultivated in temperate climates. Originating in Europe, temperate Asia, and North Africa, it is commonly used as a turf and forage grass around the world. Perennial ryegrass has been ranked as moderate in salinity tolerance for commercial cultivars, tolerating soil ECe (saturated paste extract) ranging from 4 to 8 dS m–1 (Harivandi et al., 1992). Due to wide geographical distributions of perennial ryegrass, significant natural variation in growth and whole-plant physiological responses to salinity stress are expected in diverse ecotypes within this species. However, growth and physiological responses of diverse perennial ryegrasses to increasing levels of salinity stress as well as traits associated with genetic variability in salinity tolerance are not yet fully understood in perennial ryegrass accessions varying in origins. Therefore, the objectives of this study were to investigate growth

TURFGRASS SCIENCE

Growth and Physiological Responses of Diverse Perennial Ryegrass Accessions to

Increasing Salinity

Salinity is a major abiotic stress limiting plant growth and productivity. Salinity affects plant growth and development generally through osmotic stress limiting water uptake and the excessive uptake of ions, particularly Na+ and Cl-

that ultimately interfere with various metabolic processes (Munns and Tester, 2008). Salinized plants may suffer from metabolic toxicity, nutrient deficiencies and imbalances, membrane dysfunction, and antioxidative stress, which damage tissue and induce early senescence (Essah et al., 2003). Effects of salinity on plant growth vary highly among plant species and/or within a species. In perennial turf or forage grass species, seashore paspalum (Paspalum vaginatum Sw.) had superior shoot dry weight under salinity stress compared to several other warm-season turfgrass species including Japanese lawn grass (Zoysia japonica Steud.), manila grass (Zoysia matrella

7


response, carbohydrate and ion accumulation of diverse perennial ryegrass accessions exposed to increasing salinity and to determine phenotypic traits associated with variability of salinity tolerance. The results will aid in determining natural variations in salinity tolerance of perennial ryegrasses and in providing a mechanistic formation for creating perennial grass materials that are more tolerant to salt-affected soils and water.

Materials and MethodsTen accessions of perennial ryegrass from various origins were used in the experiment including 2 wild, 3 cultivars, 2 cultivated, and 3 uncertain materials, according to USDA National Plant Germplasm System (USDA-NAGS) classification (Table 1). Grasses were grown in plastic pots (10-cm diameter, 9-cm deep) containing a sandy-loam soil with a pH of 6.9 in a greenhouse at Purdue University, West Lafayette, IN, USA. Propagation of pots containing approximately 550 g sand were sprigged with 9 to 10 tillers on March 18, 2011 and grown in a greenhouse for 24 d prior to salinity treatment. Grasses were cut to 5.0-cm high once a week. The average air temperatures were 22ºC/20ºC (day/night) and the average photosynthetically active radiation (PAR) was approximately 350 µmol m-2 s-1, with a 10-h light period of both natural and artificial light during the period of growth and treatments. Plants were well-watered and fertilized every other day with

a half-Hoagland solution (Hoagland and Arnon, 1950) at a pH of 6.6 and an electrical conductivity (EC) of 1.5 dS m-1(≈ 16 mM NaCl).

Prior to initiation of the salinity treatments, all plants were cut to a height of 5-6 cm (the height of the smallest accession) so that later measurements would be made on tissue produced after the imposition of salinity stress. The control treatment received fresh water irrigation with a half-Hoagland nutrient solution, and salinity treatments were watered with a half-Hoagland solution amended with NaCl. The NaCl solution was added to the pots through soil drenching without contact of the plants. Final NaCl concentrations were 0 (control), 50, 100, 150, 200, and 300 mM (approximately 1.5, 4.2, 8.4, 12.6, 16.8, and 25.2 dS m-1, respectively). To avoid salinity shock in the plants, these concentrations were attained gradually by increasing the NaCl concentration of the irrigation water 25 mM each day until the final concentration was reached (except for 300 mM, which was increased with 50 mM from 200 mM to 300 mM). Salinity treatments lasted 20 days. To avoid salt accumulation in the sand media, irrigation was applied manually to each pot until free drainage occurred. The lack of salt accumulation in the pots was confirmed by measuring the electrical conductivity of the leachate (VWR Traceable Digital Conductivity Meter, VWR Inc., Chicago, IL).

Table 1. Accession number (PI), origin, and collection status of perennial ryegrasses used in this experiment PI Origin Status 231587 Algeria Uncertain 231595 a Morocco Uncertain 231597 a Greece Uncertain 251141 a Yugoslavia Wild 275660 a Australia Cultivated 303011 a United Kingdom Cultivar 303022 a Netherlands Cultivated 418727 a France Wild 462339 a New Zealand Cultivar BrightStar SLT USA Cultivar

a indicates core collection accession according to USDA classification

8


Plant height (HT), leaf fresh weight (FW), leaf dry weight (DW), leaf water content (LWC), leaf Na+ and K+ concentration, chlorophyll fluorescence (Fv/Fm), fructan and water-soluble carbohydrate (WSC) concentrations were measured as indicators of growth and physiological traits for all accessions. Plant height was measured from the soil surface to the top of the uppermost leaf blade. The chlorophyll fluorescence was measured using a Portable Modulated Chlorophyll Fluorometer (OS-30P, OPTI-Sciences, Hudson, NH, USA). All the leaves for each pot were collected and fresh weight (FW) was determined immediately. Dry weight (DW) was measured after drying at 80 °C in an oven for 3 days. Leaf water content (LWC) was calculated as [(FW – DW)/FW] × 100. The water-soluble carbohydrate (WSC) and fructan were extracted from 200 mg of leaf dry tissues with 1 mL double distilled water. The WSC and fructan contents were measured using the anthrone method (Koehler, 1952), with some modifications. Leaf Na+ concentration were determined using an AA-6800 Shimadzu Atomic Absorption Spectrophotometer (Shimadzu Inc., Columbia, MD, USA) and K+ concentration using a Digital Flame Analyzer (Cole-Parmer Instrument Inc., Chicago, IL, USA).

The experiment was arranged in a split plot design, with salinity for the main plot and accession for the subplot. Each accession was randomly assigned within each treatment and each treatment was replicated three times. Statistical analysis was performed with Statistical Analysis System (SAS) (SAS Institute Inc., 2004).

Results and Discussion

Plant height decreased 10%, 13%, 22%, 27% and 29% with 50-, 100-, 150-, 200- and 300 mM NaCl, respectively, compared to the non-salinity control (Table 2). The FW, DW, LWC and Fv/Fm were unaffected by NaCl ≤ 100 mM, but were progressively reduced at 150 mM to 300 mM NaCl. For example, DW significantly decreased 30%, 36% and 48% at 150-, 200- and 300 mM NaCl, respectively; compared to the non-salinity control. Water-soluble carbohydrate concentration was unaffected by NaCl level up to 150 mM but increased 53%, 85% and 94% at 150-, 200- and 300 mM NaCl, respectively. Fructan increased from 28% to 1.8-fold, Na+ increased from 2.8- to 12.5-fold, and K+ decreased from 17% to 39% from 50 mM and 300 mM NaCl, while reductions in K+/Na+ were 36%, 52%, 1.1-, 1.3- and 1.9 fold for 50-, 100-, 150-, 200- and 300 mM NaCl, respectively; compared to the control.

Accessions differed in overall salinity tolerance based on visual observation of the senescence of older leaves exposed to increasing salinity (Fig. 1). The degree of senescence of older leaf became apparently with increasing salinity concentration. Salinity injury mainly occurred at ≥ 150 mM NaCl in some accessions. PI275660 and BrightStar SLT had better salinity tolerance followed by PI462339 with more green tissues and little leaf senescence, while PI231595 and PI251141 were highly sensitive to high salinity with severe injury. Other five accessions ranked in the middle and showed moderate salinity injury.

Table 2. Effects of 20 d of salinity treatments on plant height (HT), leaf fresh weight (FW), dry weight (DW), water content (LWC), chlorophyll fluorescence (Fv/Fm), concentrations of water-soluble carbohydrate (WSC), fructan, leaf Na+, K+ and ratio of K+/Na+

across 10 perennial ryegrass accessions

NaCl(mM) HT (cm) FW (g) DW (g) LWC (%) Fv/Fm

WSC (mg g-1

DW)

Fructan(mg g-1

DW)

Na+

(mg g-1

DW)

K+

(mg g-1

DW) K+/Na+

050

18.7 a

16.9 b

2.24 a 1.82 a

0.44 a 0.40 a

80.2 a 79.6 a

0.81 ab 0.81 ab

28.5 c 34.6 bc

17.7 d 25.9 c

3.20 d 12.2 c

38.9 a 32.3 b

12.7 a 2.74 b

100 16.2 b 1.81 a 0.40 a 79.2 a 0.82 a 36.2 c 22.7 c 14.9 c 28.0 c 1.92 b 150 14.7 c 1.25 b 0.31 b 76.5 ab 0.80 b 43.4 b 35.3 b 29.5 b 25.3 d 0.88 c 200 13.6 d 1.06 b 0.28 bc 74.6 b 0.80 c 52.7 ab 42.7 a 33.0 b 23.1 e 0.76 c 300 13.2 d 0.69 c 0.23 c 68.6 c 0.79 c 55.3 a 49.4 a 43.1 a 23.7 e 0.53 c

Means followed by the same letter within a column for a given trait were not significantly different at P < 0.05.

9


Traits of DW, LWC, Fv/Fm, and Na+ and accession of PI231595 (sensitive), PI275660 (tolerant, fast growing) and BrightStar SLT (tolerant, slow growing) were selected for assessing the patterns of variations between accessions and increasing salinity. Under the non-salinity control, there were some separations in three accessions based on selected traits; however, differences in accessions apparently became larger under salinity stress (Fig. 2). Generally, the maximum separations in accessions occurred at 150 mM NaCl for DW (Fig. 2A), at 200 mM or 300 mM NaCl for LWC (Fig. 2B), Fv/Fm (Fig. 2C), and Na+ (Fig. 2D), respectively. Compared to the control, percentage deceases in DW, LWC, Fv/Fm and increase in Na+ were also larger for accession PI231595 with increasing NaCl levels, particularly compared to PI275660.

The results suggest that traits of DW, LWC, Fv/Fm and Na+ accounted for larger variations across accessions and could be more associated with variability in high salinity tolerance, severing appropriate parameters for assessing salinity tolerance in perennial ryegrasses. Ultimately, salinity concentration, duration of stress, species and genotypes and growing conditions can all impact selection of the salinity tolerant germplasm of perennial grasses.

Acknowledgements This project is supported by the Midwest Regional Turfgrass Foundation of Purdue University and O.J. Noer Research Foundation

ReferencesCarrow, R.N. and R.R. Duncan. 1998. Salt-affected turfgrass sites: assessment and management. John Wiley & Sons, Inc., New York, USA.

Essah, P.A., R.J. Davenport, and M. Tester. 2003. Sodium influx and accumulation in Arabidopsis thaliana. Plant Physiol. 133: 307–318.

Harivandi, M.A., J.D. Butler, and L. Wu. 1992. Salinity and turfgrass culture. In: D.V. Waddington, R.N. Carrow, and R.C. Shearman (Ed), Turfgrass. Agronomy Monograph 32. pp. 207–229. Amer. Soc. Agron. Madison, WI, USA.

Hoagland, D.R., and D.I. Arnon. 1950. The water-culture method for growing plants without soil. Univ. Calif. Agri. Exp. Station. Berkley Circ: 347.

Koehler, L.H. 1952. Differentiation of carbohydrates by anthrone reaction rate and color intensity. Anal. Chem. 24: 1576–1579.

Munns, R., and M. Tester. 2008. Mechanisms of salinity tolerance. Annu. Rev. Plant Biol. 59: 651–681.

SAS Institute Inc., 2004. SAS Procedures Guide, Release 9.1 Edn. SAS Institute Inc., Cary, NC, USA

Uddin, M.K., A.S. Juraimi, M.R. Ismail, M.A. Hossain, R. Othman, and A.A. Rahim. 2012. Physiological and growth responses of six turfgrass species relative to salinity tolerance. The Sci. World J.: 905468.

Figure1.DifferentialresponsesofperennialryegrassestoincreasingNaClconcentrations

0 50 100 150 200 300 (mM)

Tolerant

Intermediate

Sensitive

10


Figure2.Thevariationofdryweight(DW)(A),leafwatercontent(LWC)(B)andchlorophyllfluorescence(Fv/Fm)(C)inaccessionPI231595,PI275660andBrightStarSLT(Bstar‐SLT)exposedto0‐,50‐,100‐,150‐,200‐,and300mMNaCl,respectively.Valuesabovex‐axiswithinasalinitycolumnindicatealeastsignificantdifference(LSD)betweenaccessionswithinasalinitylevel.Numbersontherightsiderepresentaccessionsofperennialryegrass,andvaluesoutsidetheaccessiondesignationrepresentLSDbetweenaccessionsacrosssalinitylevels.

050100150200300(mM)

A

B

C

0.02 0.03 0.02 0.03 0.14 0.05

7.9 10.7 4.2 6.3 14.9 10.5

0.19 0.24 0.23 0.13 0.17 0.17

DW

(g)

LWC

(%)

Fv/F

mN

a+(m

g g-1

DW

)

2.8 6.1 4.7 12.8 11.6 7.1

D

11

Jon M. Trappe, Aaron J. Patton and Dan Weisenberger, Department of Agronomy, Purdue University.

Trappe, J., A. Patton,, and D. Weisenberger. 2013. Efficacy of Methiozolin for Controlling Annual Bluegrass in a Creeping Bentgrass Golf Course Putting Green Update. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 12-14.

Summary: Annual bluegrass (Poa annua) continues to be a problematic weed on golf course putting greens because of its poor disease and heat tolerance. Methiozolin is a new herbicide that selectively controls annual bluegrass in creeping bentgrass (Agrostis stolonifera) golf course putting greens. The objective of our research was to determine the effect of methiozolin application rate and timing on annual bluegrass coverage, bentgrass injury, and overall turf quality in a mixed creeping bentgrass/annual bluegrass putting green. Applications of methiozolin using the high 0.9 lb ai/A applied in March + April or March + April + May, or paclobutrazol applied in April + May at 0.25 lb ai/A were more effective at reducing annual bluegrass coverage. Bentgrass injury and turf quality were typically never below acceptable levels for either rate or timing of methiozolin. Although this herbicide is not currently registered for use in the United States, it is currently being evaluated by many researchers and golf course superintendents around the country through a US EPA experimental use permit.

Additional index words: ABG, MRC-01, PoaCure, Poa annua.

biosynthesis. It is available in an EC formulation (2.1 lb/gal) and is reported to have both PRE and POST emergent activity and enters the plant primarily via root uptake (Flessner et al., 2012). Previous unpublished research performed by the same researchers as this experiment conducted another study on a golf course fairway in West Lafayette, IN comparing spring and fall application timings of methiozolin and concluded fall applications were more effective at controlling annual bluegrass. However, it is important to evaluate the efficacy of methiozolin on annual bluegrass control in golf course putting greens in the spring.

Therefore, the objective of our research was to determine the effect of methiozolin application rate and timing on annual bluegrass coverage, bentgrass injury, and overall turf quality in a mixed creeping bentgrass/annual bluegrass putting green.

Materials and Methods

This research was conducted on a putting green located at Ackerman Hills Golf Course in West Lafayette, IN. The putting green was a creeping bentgrass and annual bluegrass mixture with approximately 40% annual bluegrass. The putting green was a native soil putting green that is

TURFGRASS SCIENCE

Efficacy of Methiozolin for Controlling Annual Bluegrass in a Creeping Bentgrass

Golf Course Putting Green

Annual bluegrass (Poa annua) is one of the most problematic weeds on golf courses and athletic fields. It is particularly problematic on golf course putting greens, as it has poor disease and heat tolerance, provides an inconsistent playing surface, and is typically more expensive to maintain than creeping bentgrass (Agrostis stolonifera). Annual bluegrass is also problematic because it is a difficult to control weed on golf course putting greens as there are limited cultural and chemical control methods.

Methiozolin (PoaCureTM) is a new herbicide currently involved in an Experimental Use Permit program in many states in the U.S. (Moghu Research Center, 2013). It has been reported to have good efficacy on annual bluegrass and good safety on many cool-season species including creeping bentgrass (Brosnan et al., 2013). Methiozolin is an isoxazoline herbicide that inhibits cell wall

12


approximately 60 years old and maintained under typical golf course putting green conditions.

Experimental design was a randomized complete block design with three replications. Plots were treated with single applications on the 15 March, 15 April, 15 May or sequential applications with March + April and March + April + May timings. Treatments included methiozolin (MRC-01) at 0.9 lb ai/A or 0.45 lb ai/A, as well as an untreated control. Paclobutrazol was included as a treated control and was treated on 15 April and 15 May at 0.25 lb ai/A. Herbicides were applied in 30 gal/A water with a CO2 pressurized backpack sprayer at 30 psi. Plots were evaluated for creeping bentgrass injury (1-9, 9=no injury, 7=acceptable injury), turfgrass quality (1-9, 9=dense, healthy turf, 7=acceptable turf quality), and percent annual bluegrass coverage. All data were analzed using SAS (SAS Institute, Inc.). Means were separated using Fisher’s protected least significance difference test when F tests were significant at α=0.05.

Results and DiscussionAlthough there were statistical differences among treatments for bentgrass injury, there were no instances in which injury was rated below the acceptable level (acceptable injury ≥7) across all rating dates for all treatments (data not shown). Similarly, turf quality was typically not rated below the acceptable level (acceptable quality ≥7) for any treatments on the majority of rating dates (data not shown). Rate and timing each influenced annual bluegrass coverage on multiple dates (Table 1). In general, spring sequential applications of methiozolin using the 0.9 lb ai/A applied in March + April or March + April + May were more effective at reducing annual bluegrass coverage on all rating dates. This trend in effectiveness of 0.9 lb ai/A methiozolin with early sequential timings is consistent with findings of a similar study performed in Tennessee (Brosnan et al., 2013; Trappe et al., 2012) and Pennsylvania (Han et al., 2012). Han et al., (2012) evaluated spring, summer, and fall application timings on a creeping bentgrass/annual bluegrass putting green in Pennsylvania using a similar treatment structure as this study and concluded fall applications reduced annual bluegrass populations more than spring, while there was no significant reduction of annual bluegrass populations compared to the untreated

control from summer applications. These reports indicate the effectiveness of methiozolin for gradual removal of annual bluegrass in a creeping bentgrass putting green.

AcknowledgementsThe authors would like to thank Quincy Law, Tony Feitz, and Geoff Schortgen for their assistance in data collection. The authors also want to express their thanks to the Midwest Regional Turf Foundation for partial funding of this research.

ReferencesBrosnan, J.T., S. Calvache, G.K. Breeden, and J.C. Sorochan. 2013. Rooting depth, soil type, and application rate effects on creeping bentgrass injury with amicarbazone and methiozolin. Crop Sci. 53:655-659.

Flessner, M.L., G.R. Wehtje, and J.S. McElroy. 2012. Determination of methiozolin absorption and translocation using herbicide biosassays and radio-labeled methodology. ASA, CSSA, and SSSA Abstracts. 21-24 October, 2012. Cincinnati, OH.

Han, K.M., and J.E. Kaminski. 2012. Influence of methiozolin rates and application timings on Poa annua populations. ASA, CSSA, and SSSA Abstracts. 21-24 October, 2012. Cincinnati, OH.

Moghu Research Center. 2013. Website. Accessed on 3 March, 2013. http://www.moghu.com/eng/02_product/01_product.php

Trappe, J.M., A.J. Patton, D. Weisenberger, G. Breeden, and J. Brosnan. 2012. Methiozolin rate and spring application timing affect annual bluegrass control on putting greens. ASA, CSSA, and SSSA Abstracts. 21-24 October, 2012. Cincinnati, OH.

13


Table 1. The effect of methiozolin rate and timing on annual bluegrass coverage. Annual bluegrass coverage Methiozolin application date Rate 5/31 6/15 7/2 8/8 lb ai/A ---------------------------------%---------------------------------- 15 March 0.45 40 bcd a 52 a 42 bcd 22 a-e 15 March 0.90 42 bc 45 a 27 e 12 e 15 April 0.45 52 ab 50 a 47 abc 18 cde 15 April 0.90 48 ab 45 a 52 ab 30 abc 15 May 0.45 50 ab 50 a 42 bcd 27 a-d 15 May 0.90 50 ab 45 a 50 ab 32 abc March + April 0.45 48 ab 50 a 47 abc 33 ab March + April 0.90 27 d 28 cd 33 de 12 e April + May 0.45 43 ab 45 a 37 cde 15 de April + May 0.90 45 ab 40 abc 40 bcd 15 de March + April + May March + April + May

0.45 40 bcd 45 a 43 a-d 20 b-e 0.90 28 cd 23 d 27 e 12 e

Paclobutrazol 0.25 28 cd 32 bcd 47 abc 20 b-e Untreated - 56 a 42 ab 55 a 35 a

a Within columns, means followed by the same letter are not different (LSD, =0.05).

Fig. 1. The outlined area in the figure above indicates a plot that had approximately a 30% reduction in annual bluegrass coverage after receiving 0.9 lb ai/A of methiozolin on 15 March, 15 April, and 15 May 2012. Photo taken on 13 June 2012.

14

Aaron J. Patton and Dan Weisenberger, Department of Agronomy, Purdue University.

Patton, A., and D. Weisenberger. 2013. Dandelion Control and Flower Suppression with Defendor Herbicide. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 15-19.

Summary: Dandelion (Taraxacum officinale) is the most easily identified broadleaf weed in lawns and possibly the most common. Many herbicides including 2,4-D do a good job controlling dandelions when applied in the fall or late spring, but even ester formulations of 2,4-D can be ineffective if applied too early in spring. The specific objectives of this study were to compare dandelion control and dandelion bloom suppression with 1) late-winter (mid-March) versus spring (late April) application timings of Defendor+Dimension (dithiopyr), 2) single versus sequential applications of Defendor+Dimension, and 3) whether or not the addition of Trimec Classic (2,4-D + MCPP + dicamba) would improve dandelion control when added to the sequential application timing. The overarching objective was to evaluate the efficacy of Defendor for dandelion control and bloom suppression. Dandelion coverage was reduced most when two applications of Defendor as part of a Dimension split application was used. Application timing in March of Defendor+Dimension successfully inhibited dandelion bloom. April applications were too late to provide dandelion flower suppression. Dandelion control from March applications with Defendor+Dimension was not improved when Trimec Classic was added to the second sequential application in April likely because little dandelion foliage was present when the Trimec Classic was applied. About 30-40% of the dandelions initially thought to be controlled by two sequential applications of Defendor+Dimension fully recovered, while others were completely controlled. If early spring broadleaf weed control is needed, Defendor is an herbicide that provides early season suppression of dandelions and keeps them from flowering.

Additional index words: dithiopyr, florasulam, Taraxacum officinale

Many herbicides do a good job controlling dandelions, especially those containing 2,4-D. Fall is the best time to control perennial broadleaves like dandelion and both amine or ester formulations of 2,4-D provide optimum dandelion control in the fall. If dandelions are problematic in the spring, dandelion control can be optimized in the cooler months (April) by using ester formulations of broadleaf herbicides. However, even ester formulations can be ineffective if applied too early in spring. For the lawn care industry, dandelions pose a problem in that they flower in the spring before an application of broadleaf herbicide is applied which reduces customer satisfaction as the customers see flowering dandelions. A typical scenario is that dandelions flower after the application of a preemergence herbicide for crabgrass has been applied in the first round of treatments but before a broadleaf herbicide can be applied in the second round of treatments.

TURFGRASS SCIENCE

Dandelion Control and Flower Suppression with Defendor Herbicide

Dandelion (Taraxacum officinale) is the most easily identified broadleaf weed in lawns and possibly the most common. Dandelion is a perennial broadleaf weed that forms a deep taproot that helps it survive tough environmental growing conditions in a wide range of soils even though it prefers soils high in potassium. It is a prolific seed producer and the seed readily germinates which helps make this weed problematic.

15


A new herbicide called Defendor (florasulam), available in spring 2013, may offer turf mangers a solution to this problem. We initiated research to better learn how to maximize dandelion control with Defendor. The specific objectives of this study were to compare dandelion control and dandelion bloom suppression from 1) late-winter (mid-March) versus spring (late April) application timings of Defendor+Dimension (dithiopyr), 2) single versus sequential applications of Defendor+Dimension, and 3) whether or not the addition of Trimec Classic (2,4-D + MCPP + dicamba) would improve dandelion control when added to the sequential application timing. The overarching objective was to evaluate the efficacy of Defendor for dandelion control and bloom suppression.

Materials and MethodsThe experiment was conducted at the W.H. Daniel Research and Diagnostic Center in West Lafayette, IN. The site was a Kentucky bluegrass blend with a uniform cover by dandelion. Experimental design was randomized complete block with four replications and an individual plot size of 25 ft2.

Plots were mown at 2 inches as needed.

Plots were treated with herbicide 13 March and 25 April. Herbicides were applied in 86 gpa water with a CO2-pressurized sprayer at 30 psi. An untreated check was included for comparison. Dandelion coverage was visually rated as percent coverage. Percent control of dandelion was also rated on a 0 to 100 scale with 100 equal to total control. Bloom reduction was rated on a 0 to 100 scale with 100 equal to total bloom reduction (no bloom or seedhead produced). All data were analyzed using SAS (SAS Institute, Inc). Means were separated using Fisher’s protected least significant difference when F tests were significant at α=0.05.

Results and DiscussionPlant Dandelion coverage was reduced most when two applications of Defendor as part of a Dimension split application was used compared to single Defendor+Dimension application in March or April (Table 1, Figs. 1 and 3). Application in March of Defendor+Dimension were the only treatments that successfully inhibited dandelion bloom (Table 2, Figs. 1 and 2). Dandelion control from March applications with Defendor+Dimension (Fig. 3) was not improved when Trimec Classic was added to the second sequential application in April (Table 1 and 2). This was likely because little dandelion foliage was present when the Trimec Classic was applied and thus little foliar uptake could take place. Single applications of Defendor+Dimension applied in March vs. April yielded similar results in dandelion coverage, but April applications were too late to provide dandelion flower suppression (Table 1).

About 30-40% of the dandelions initially thought to be controlled by two sequential applications of Defendor+Dimension fully recovered, while others were completely controlled. Dandelion regrowth from taproots began about 4 June (6 weeks after the sequential application) and by 17 July dandelions that survived the two Defendor+Dimension applications had recovered (data not shown).

Fall herbicide applications work well to control perennial broadleaves and this should be the preferred application timing for turf professionals. However, if early spring broadleaf weed control is needed, Defendor is an herbicide that provides early season suppression of dandelions and keeps them from flowering.

16


Table 1. Dandelion coverage from various spring applications of Dimension and Defendor combination products.

Dandelion coverage Application Herbicide Rate a timing 2 April 19 April 7 May 30 May 12 June 2 July

ai/A %Dimension 2EW 0.25 13 March 21 4 c b 2 c 0 d 2 c 18 bc + Defendor 0.417L 0.013 fb c Dimension 2EW 0.25 25 April + Defendor 0.417L 0.013 Dimension 2EW 0.25 13 March 24 5 c 2 c 1 cd 1 c 14 c + Defendor 0.417L 0.013 fb Dimension 2EW 0.25 25 April + Defendor 0.417L 0.013 + Timec Classic 3.5a

Dimension 2EW 0.38 13 March 33 6 c 3 c 21 b 29 ab 46 a + Defendor 0.417L 0.013 Dimension 2EW 0.38 25 April 31 a 11 bc 5 c 30 b + Defendor 0.417L 0.013 Dimension 2EW 0.25 25 April 28 ab 13 b 19 b 25 bc + Timec Classic 3.5a

Dimension 2EW 0.25 13 March 36 36 a 34 a 35 a 36 a 49 a fb Dimension 2EW 0.25 25 April Untreated 29 24 b 19 b 21 b 25 ab 30 b

P-value 0.0557 <0.0001 <0.0001 <0.0001 <0.0001 0.0005

a Rate of application was pints per acre. b Means followed by the sample letter are not significantly different. c fb = “followed by” sequential application.

17


Table 2. Dandelion control and percent bloom suppression from various spring applications of Dimension and Defendor combination products.

control bloom reduction Application Herbicide Rate a Timing 2 April 7 May 2 April

ai/A % %Dimension 2EW 0.25 13 March 58 a b 95 a 100 a + Defendor 0.417L 0.013 fb c Dimension 2EW 0.25 25 April + Defendor 0.417L 0.013 Dimension 2EW 0.25 13 March 48 b 94 a 100 a + Defendor 0.417L 0.013 fb Dimension 2EW 0.25 25 April + Defendor 0.417L 0.013 + Timec Classic 3.5a

Dimension 2EW 0.38 13 March 38 c 89 b 100 a + Defendor 0.417L 0.013 Dimension 2EW 0.38 25 April 3 d 1 b + Defendor 0.417L 0.013 Dimension 2EW 0.25 25 April 9 c 0 b + Timec Classic 3.5a

Dimension 2EW 0.25 13 March 0 d 0 d 0 b fb Dimension 2EW 0.25 25 April Untreated 0 d 0 d 3 b

P-value <0.0001 <0.0001 <0.0001

a Rate of application was pints per acre. b Means followed by the sample letter are not significantly different. c fb = “followed by” sequential application.

18


Fig. 1. Dimension (0.25 lb ai/A) + Defendor (0.013 lb ai/A) applied on 13 March. Photo taken 2 April. Notice the lack of flowering.

Fig. 2. Dimension (0.38 lb ai/A) + Defendor (0.013 lb ai/A) applied on 13 March. Photo taken 2 April. Notice the lack of flowering.

Fig. 3. Herbicide injury on dandelion from Defendor application on 13 March. Photo taken 2 April. Notice the lack of flowering.

Fig. 4. Untreated control.

19

Aaron J. Patton and Dan Weisenberger, Purdue University.Greg Breeden and Jim Brosnan, University of Tennessee

Patton, A., G. Breeden, J. Brosnan and D. Weisenberger. 2013. Herbicide Selection and Timing Influences Ground Ivy Control – 2012 Results. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 20-26.

Summary: Ground ivy (Glechoma hederacea), sometimes referred to as creeping Charlie, is a creeping perennial broadleaf species that is a common weed in turf and difficult to control once established. Previous reports have documented the efficacy of fall herbicide applications for ground ivy control. The objectives of this experiment were to 1) determine which herbicides most effectively control ground ivy, 2) determine which application timing (fall vs. spring) is most effective across two different environments, and 3) determine if any herbicide by application timing interactions exist. Herbicides containing 2,4-D, fluroxypyr, triclopyr, iodosulfuron, thiencarbazone, and aminocyclopyrachlor or mixtures of these ingredients provided good ground ivy control in our experiment in both Indiana and Tennessee. With the exception of metsulfuron, most of the products used in the experiment provided similar levels of ground ivy control when used in either the spring or the fall. Thus, although timing is critical, proper herbicide selection is more critical for weed control. NOTE: State registration for Imprelis was cancelled and federal registration was later cancelled by the U.S. Environmental Protection Agency. This cancellation does not allow the continued use of Imprelis herbicide in the U.S. Any such applications are illegal.

Additional index words: 2,4-D; Blade; Escalade 2; fluroxypyr; metsulfuron; Spotlight; sulfentrazone; triclopyr; Trimec Classic; Turflon Ester Ultra, TZONE.

that triclopyr provides effective and consistent control of ground ivy (Kohler et al., 2004; Reicher and Weisenberger., 2007). Fluroxypyr has also been described as effective, though slightly less effective and consistent than triclopyr (Reicher and Weisenberger., 2007). Additionally, 2,4-D also effectively controls ground ivy when applied alone (Kohler et al., 2004) or when mixed with 2,4-DP (dichlorprop) or MCPP (Vrabel, 1987; Borger et al., 2002). Tank-mixes with 2,4-D and triclopyr also increase control of ground ivy when tank-mixed with other herbicides (Olson and Wright, 1988; Vrabel, 1987). The activity of other herbicides is not fully known.

Fall applications are typically recommended for perennial broadleaf weed control with applications at or near the first frost are considered most effective. Previous reports have documented the efficacy of fall applications for ground ivy control (Reicher and Weisenberger, 2007). Herbicide applications from 1 September to 1 November in West Lafayette, IN are highly efficacious, while applications made after 15 November can be less effective(Reicher and Weisenberger., 2007). Thus, a wide window of dates can be used in the fall

TURFGRASS SCIENCE

Herbicide Selection and Timing Influences Ground Ivy Control – 2012 Results

Ground ivy (Glechoma hederacea), sometimes referred to as creeping Charlie, is a creeping perennial broadleaf speices that is a common weed in turfgrass and difficult to control once established. Among the cultural practices that typically control weeds, implementing recommended nitrogen fertilization practices (≥4 lbs N/1000 ft2) can reduce ground ivy coverage compared to non-fertilized turf (Kohler et al., 2004) but it is unknown how mowing, irrigation, drainage, and soil compaction influence ground ivy populations. Despite a beneficial reduction in ground ivy from fertilization, herbicides are needed for effective control. Multiple experiments have revealed

20


to control ground ivy but little is known about how the efficacy of spring applications compares to fall applications. Many lawn care companies and home owners also treat weeds in the spring, including ground ivy, as this is when these weeds are more noticeable and homeowners generally have more interest and energy for yard work. The objectives of this experiment were to 1) determine which herbicides most effectively control ground ivy, 2) determine which application timing (fall vs. spring) is most effective across two different environments, and 3) determine if any herbicide by application timing interactions exist.

Materials and MethodsThe experiment was conducted at the W.H. Daniel Turfgrass Research and Diagnostic Center in West Lafayette, IN and at Egwani Farms Golf Course in Rockford, TN. The site was a Kentucky bluegrass blend in Indiana and a mixed sward of common bermudagrass and tall fescue in Tennessee. Both locations had uniform cover by ground ivy at treatment initiation. Plots were mown at 2 inches in Indiana and 4 inches in Tennessee. Experimental design was a factorial with two application timings (fall and the following spring), several herbicides, three replications and a plot size of 25 ft2 in IN and 50ft2 in TN. Herbicides and rates in the experiment included 2,4-D amine (4 pts/A), 2,4-D ester (4 pts/A), Blade (metsulfuron) (0.5 oz/A), Celsius (thiencarbazone + iodosulfuron + dicamba) (2.5 oz/A), Escalade 2 (2,4-D + fluroxypyr + dicamba) (3 pt/A), Imprelis (aminocyclopyrachlor) (4.5 fl oz/A), Spotlight (fluroxypyr) (1.33 pt/A), Trimec Classic (2,4-D + mecoprop + dicamba) (4 pt/A), Turflon Ester Ultra (triclopyr) (1 qt/A yr 2), and TZONE (triclopyr + sulfentrazone + 2,4-D + dicamba) (4 pt/A).

Plots were treated with herbicide on 11 Oct 2011 (fall) or 17 April 2012 (spring) in IN, and on 12 Oct 2011 (fall) or 18 April 2012 (spring) in TN. Herbicides were applied in 87 gpa water in IN and 30 gpa water in TN with a CO2-pressurized sprayer at 30 psi. Ground ivy percent coverage was visually rated. All data were analyzed using SAS (SAS Institute, Inc). Means were separated using Fisher’s protected least significant difference when F tests were significant at α=0.05.

Results and DiscussionIndianaThe main effect of herbicide was significant on all spring and summer rating dates but not in the fall. When treatment effects were analyzed in summer, the main effect of timing was not significant, but there was a timing-by-herbicide interaction on both the June and July rating dates. When rated in June, all herbicides at both timings reduced ground ivy coverage more than the untreated check. However, Blade (metsulfuron) applied in the spring or fall and Trimec Classic (2,4-D + dicamba + MCPP) applied in the fall had greater ground ivy coverage (≥7%) than a large group of herbicides that reduced ground ivy coverage to ≤2% (Table 1). The timing-by-herbicide interaction in June was due to an inconsistent response from Blade and Celsius (thiencarbazone + iodosulfuron + dicamba) which provided better ground ivy control when applied in the spring than in the fall. All herbicides except Blade applied in the fall reduced ground ivy coverage when compared to the untreated check when rated one month later in July.TennesseeThe main effect of herbicide selection was significant on all rating dates in TN (Tables 2 and 3). When rated approximately three weeks after the initial fall application timing on 12 October 2011, 2,4-D, Escalade 2, Imprelis, Spotlight, Trimec Classic and TZONE were among the herbicides that decreased ground ivy coverage most, including lower than the untreated check and the Celsius treatment (Table 2). By 1 December, fall applications of all herbicides provided equivalent control of ground ivy (Table 2). By May and July 2012 the following year, all herbicides at both application timings reduced ground ivy coverage to ≤12% (Tables 2 and 3) while ground ivy coverage in the untreated check remained ≥67%.There were significant timing-by-herbicide interactions on the 1 and 15 May rating dates, but only a timing effect on the 31 May and 2 July ratings. The interaction on 1 May was caused by a difference in control between spring and fall Celsius applications which was a result of the slower mode of action from this herbicide (Table 2). By 15 May, both Celsius application timings were similar. Additionally, on 15 May, Blade

21


provided less ground ivy control when applied in the spring than in the fall (Table 2). The significant effect of timing on 31 May and 2 July resulted in better control from spring timings than fall timings, regardless of herbicide selected. Although this could reflect that spring timings were better than fall in Tennessee, it could also reflect that ground ivy had begun to recover in fall applied plots by late May 2012, 7.5 months after these plots were treated. Additionally, the magnitude (4 to 9%) of this difference is relatively minor considering that the untreated plots had ≥76% on those same rating dates.It is not clear why control was better in TN than IN with some products, but could be due to the fact that the location in IN was full-sun possibly with a thicker, waxier leaf cuticle while the TN location was mostly-shaded.

ConclusionHerbicides containing 2,4-D, fluroxypyr, triclopyr, iodosulfuron, thiencarbazone, and aminocyclopyrachlor or mixtures of these ingredients provided good ground ivy control in our experiment in both Indiana and Tennessee. The majority of the data suggests that fall and spring applications work equally well, although in Tennessee spring applications reduced ground ivy 4 to 9% more than fall applications when rated in May and July. Despite this small difference in control from spring and fall applications timings, we still recommend that fall is the best time to control perennial broadleaf weeds. Although fall timing is recommended for perennial broadleaf control, this research demonstrates that proper herbicide selection is more critical than timing.

Acknowledgements The authors want to express their thanks to the Midwest Regional Turf Foundation for partial funding of this research.

ReferencesBorger, J.A., T.L. Watschke, and J.T. Brosnan. 2002. Broadleaf weed control in 2002. In the 57th Annual Meeting of the Northeastern Weed Science Society. Vol.57, 2003, p.105

Kohler, E.A., C.S. Throssell, and Z.J. Reicher. 2004. Cultural and chemical control of ground ivy (Glechoma hederacea). HortScience 39(5): 1148-1152.

Olson, B.D. and W.G. Wright. 1988. Postemergence broadleaf weed control in turf with triclopyr and phenoxy herbicide. Proceedings of the 42nd Annual Meeting of the Northeastern Weed Science Society. Vol.42, January 1988, p.177

Reicher, Z.J. and D.V. Weisenberger. 2007. Herbicide selection and application timing in the fall affects control of ground ivy. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0831-01-RS.

Vrabel, T.E. 1987. Wild violet control in cool season turf. Proceeding of 41st Annual Meeting of the Northeastern Weed Science Society. Vol.41, January 1987, p.237.

22


5

Table 1. Herbicide and timing effects on ground ivy coverage in Indiana.

Ground Ivy Coverage 9 Nov 1 Dec 17 May 5 June 2 July Herbicide Rate Timinga 2011 2011 2012 2012 2012

%2,4-D amine 4 pt/A fall 40 27 2 c b 2 fg 9 c 2,4-D amine 4 pt/A spring 0 c 0 g 0 c 2,4-D ester 4 pt/A fall 38 28 2 c 1 fg 11 c 2,4-D ester 4 pt/A spring 0 c 0 g 2 c Blade 0.5 oz/A c fall 45 27 28 ab 13 c 47 b Blade 0.5 oz/A c spring 5 c 8 d 17 c Celsius 2.5 oz/A fall 40 30 23 b 4 def 2 c Celsius 2.5 oz/A spring 0 c 1 g 0 c Escalade 2 3 pt/A fall 40 25 3 c 2 fg 2 c Escalade 2 3 pt/A spring 0 c 0 g 1 c Imprelis 4.5 fl oz/A fall 43 23 0 c 0 g 0 c Imprelis 4.5 fl oz/A spring 0 c 0 g 0 c Spotlight 1.33 pt/A fall 40 22 1 c 1 g 2 c Spotlight 1.33 pt/A spring 0 c 0 g 2 c Trimec Classic 4 pt/A fall 42 27 7 c 7 de 2 c Trimec Classic 4 pt/A spring 1 c 2 fg 4 c Turflon Ester Ultra 1 pt/A fall 33 20 0 c 1 g 1 c Turflon Ester Ultra 1 pt/A spring 0 c 0 g 2 c TZONE 4 pt/A fall 32 17 4 c 3 efg 5 c TZONE 4 pt/A spring 1 c 2 fg 4 c Untreated Check fall 42 22 35 a 45 b 45 b Untreated Check spring 33 a 57 a 73 a

ANOVATiming <0.0001 0.1740 0.4994 Herbicide NS NS <0.0001 <0.0001 <0.0001 Timing × Herbicide <0.0001 <0.0001 0.0157

a Plots were treated with herbicide on 11 October 2011 (fall) or 17 April 2012 (spring). b Within columns, means followed by the same letter are similar. c Treatment included a nonionic surfactant at 0.25% (v/v).

23


6

Table 2. Herbicide and timing effects on ground ivy coverage in Tennessee.

Ground Ivy Coverage 1 Nov 1 Dec 1 May 15 May Herbicide Rate Timinga 2011 2011 2012 2012

%2,4-D amine 4 pt/A fall 7 cd 2 b 3 e b 0 d 2,4-D amine 4 pt/A spring 8 e 3 cd 2,4-D ester 4 pt/A fall 17 cd 0 b 2 e 3 cd 2,4-D ester 4 pt/A spring 5 e 0 d Blade 0.5 oz/A c fall 28 bcd 0 b 5 e 3 cd Blade 0.5 oz/A c spring 5 e 12 c Celsius 2.5 oz/A fall 47 ab 0 b 5 e 0 d Celsius 2.5 oz/A spring 22 d 3 cd Escalade 2 3 pt/A fall 7 cd 0 b 0 e 0 d Escalade 2 3 pt/A spring 5 e 0 d Imprelis 4.5 fl oz/A fall 8 cd 3 b 3 e 0 d Imprelis 4.5 fl oz/A spring 2 e 0 d Spotlight 1.33 pt/A fall 12 cd 2 b 2 e 5 cd Spotlight 1.33 pt/A spring 0 e 0 d Trimec Classic 4 pt/A fall 7 cd 0 b 0 e 0 d Trimec Classic 4 pt/A spring 3 e 3 cd Turflon Ester Ultra 1 pt/A fall 32 bc 5 b 3 e 2 d Turflon Ester Ultra 1 pt/A spring 8 e 2 d TZONE 4 pt/A fall 5 d 2 b 2 e 5 cd TZONE 4 pt/A spring 0 e 0 d Untreated Check fall 65 a 73 a 77 a 87 a Untreated Check spring 65 b 67 b

ANOVATiming 0.0006 0.2874 Herbicide 0.0009 <0.0001 <0.0001 <0.0001 Timing × Herbicide <0.0001 0.0050

a Plots were treated with herbicide on 12 October 2011 (fall) or 18 April 2012 (spring). b Within columns, means followed by the same letter are similar. c Treatment included a nonionic surfactant at 0.25% (v/v).

24


7

Table 3. Herbicide effects on ground ivy coverage in Tennessee. Plots were treated with herbicide on 12 October 2011 (fall) or 18 April 2012 (spring). Results are combined across application timings.

Ground Ivy Coverage 31 May 2 July Herbicide Rate 2012 2012

%2,4-D amine 4 pt/A 2 b a 12 b 2,4-D ester 4 pt/A 2 b 11 b Blade 0.5 oz/A b 2 b 8 b Celsius 2.5 oz/A 3 b 10 b Escalade 2 3 pt/A 2 b 3 b Imprelis 4.5 fl oz/A 1 b 4 b Spotlight 1.33 pt/A 3 b 10 b Trimec Classic 4 pt/A 1 b 8 b Turflon Ester Ultra 1 pt/A 0 b 8 b TZONE 4 pt/A 4 b 10 b Untreated Check 76 a 78 a

ANOVATiming 0.0062 0.0003 Herbicide <0.0001 <0.0001 Timing × Herbicide <0.2685 0.4885

a Within columns, means followed by the same letter are similar. b Treatment included a nonionic surfactant at 0.25% (v/v).

8

Table 4. Herbicide timing effects on ground ivy coverage in Tennessee. Results are combined across herbicide.

Ground Ivy Coverage 31 May 2 July Timing Date 2012 2012

%Fall 11 October 2011 11 a a 19 a Spring 17 April 2012 7 b 10 b

ANOVATiming 0.0062 0.0003 Herbicide <0.0001 <0.0001 Timing × Herbicide <0.2685 0.4885

a Within columns, means followed by the same letter are similar.

25


9

Fig. 1. Celsius (thiencarbazone + iodosulfuron + dicamba) applied at 2.5 oz/A on 11 Oct 2011. Photo taken on 5 June 2012 in Indiana.

Fig. 2. Spotlight applied at 1.33 pt/A on 11 Oct 2011. Photo taken on 5 June 2012 in Indiana.

Fig. 3. Turflon Ester Ultra applied at 2 qt/A on 11 Oct 2011. Photo taken on 5 June 2012 in Indiana.

Fig. 4. Trimec Classic applied at 4 pt /A on 11 Oct 2011. Photo taken on 5 June 2012 in Indiana.

Fig. 5. Escalade 2 applied at 3 pt/A on 11 Oct 2011. Photo taken on 5 June 2012 in Indiana.

Fig. 6. Untreated check plot. Photo taken on 5 June 2012 in Indiana.

26

Quincy D. Law and Aaron J. Patton, Department of Agronomy, Purdue University.

Law, Q and A. Patton, A. 2013. Selecting Turfgrasses and Mowing Strategies to Reduce Mowing Requirements. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 27-31.

Summary: Mowing remains as one of the most important and energy-intensive cultural practices in maintaining a turfgrass stand. However, little research has been published on the influence of a particular mowing regime on the number of annual mowing events. Furthermore, the impact of turfgrass species and cultivars on mowing requirements is largely unknown. The objectives of this study were to 1) determine if an alternate mowing regime will reduce mowing requirements and 2) determine if turfgrass species and varieties with differing growth rates influence the mowing requirements. The results from the first year of this experiment indicate that both mowing regime and turfgrass selection are important factors in the annual mowing requirements of a turf sward.

Additional index words: grass clippings, growth rate, Kentucky bluegrass, one-third rule, tall fescue.

recommendations to return or mulch clippings to the lawn (Reicher et al., 1994; Reicher et al., 2006), Graper and Munk estimated in 1994 that 15 to 20% of residential waste may be composed of grass clippings during the summer months. With landfills no longer accepting grass clippings and educational outreach on the subject, this percentage has decreased significantly. Returning grass clippings to the lawn when mowing has been shown to improve color (Heckman et al., 2000) and nitrogen use efficiency (Kopp and Guillard, 2002), as well as increase nitrogen uptake (Starr and DeRoo, 1981) and overall dry matter yield (Kopp and Guillard, 2002). Though returning clippings was once thought to contribute to thatch accumulation, the rapid decomposition of grass clippings observed by Kopp and Guillard (2004) supports the conclusions of Beard (1976), Haley et al. (1985), and Johnson et al. (1987) that thatch accumulation is not increased by the practice of returning clippings to turfgrass. With the benefits associated with returning grass clippings, it is an element of mowing that needs to be considered when selecting a mowing strategy.

Another important aspect of mowing is the turfgrass plant itself. Madison (1962) showed that different species can have different growth rates. Varietal selection is also important, as Wilhelm and Nelson (1978) revealed that high-yielding genotypes display greater leaf elongation rates than low-yielding genotypes. As a result, turfgrass

TURFGRASS SCIENCE

Selecting Turfgrasses and Mowing Strategies to Reduce Mowing Requirements

Mowing remains one of the most important and energy-intensive cultural practices in maintaining a turfgrass stand. Even with proper moisture, fertility, and pest control, incorrect mowing of turf can be detrimental to plant growth and function. The practice of mowing is a plant stress that removes green tissue, thereby reducing the plant’s ability to undergo photosynthesis and produce the carbohydrates it requires (Christians, 2011). It is recommended not to remove excessive leaf tissue in a single mowing to limit this stress. Many homeowners and lawn services mow on a schedule rather than as needed despite extension publication recommendations to mow frequently enough as to not remove more than one-third of the leaf blade in a single mowing (Reicher et al., 2006). Mowing frequency not only impacts plant health, but energetics and emissions as well. Mowing more frequently results in a higher energy requirement and greater emissions.

In addition to mowing frequency, grass clipping management is another important and often overlooked aspect of mowing. Even with extension

27


selection is an important consideration when attempting to reduce the mowing requirement of a turf sward. The objectives of this study were to 1) determine if an alternate mowing regime will reduce mowing requirements and 2) determine if turfgrass species and varieties with differing growth rates influence the mowing requirements.

Materials and MethodsResearch was conducted at the W.H. Daniel Turfgrass Research and Diagnostic Center in West Lafayette, IN. In April of 2011, three cultivars of tall fescue (Festuca arundinacea Schreb.) were planted at 6 lb 1000 ft-2 (294 kg ha-1) and three cultivars of Kentucky bluegrass (Poa pratensis L.) were planted at 2 lb 1000 ft-2 (98 kg ha-1) (Table 1). Cultivars were selected for this experiment based upon their growth in preliminary trials and their similar appearance and stress tolerance in previous field trials in West Lafayette, IN (data not shown).

The experiment was a two by three by two by two factorial design (2 × 3 × 2 × 2) with two species, three cultivars (slow, moderate, and fast growth rates), two mowing frequencies, and two grass clipping treatments. The experimental design was a split plot with four complete blocks. Whole plots of species and cultivar were randomized within blocks, and mowing frequency and clipping collection treatments were subunits randomized within whole plots.

A total of four mowing strategies were applied. Two separate mowing frequencies based upon 1) a standard homeowner with plots mown on the same day each week, and 2) the “one-third rule” using daily measurements to determine the appropriate mowing date based upon removing one-third of the leaf tissue. Additionally, for each of the two mowing frequencies described, clippings were either 1) collected with a rear collection bag attachment, or 2) mulched by the mower and returned. All mowing events were recorded for each split plot so that a total number of annual mowing events can be tabulated for each cultivar and mowing strategy for both species.

All plots were mown at 2.75 in (7 cm) with a Troy-Bilt TriAction 21 in (53 cm) wide deck walk-behind push mower. Thus, plots mown based on the one-third rule were cut when turf reached a height of

4.1 in (10.4 cm). Moreover, if weekly-mown plots hadn’t grown to a height of at least 3.25 in (8.3 cm), mowing was delayed until at least the next week. To collect annual yield data, the grass clippings from the weekly-mown treatments with clippings removed were collected, dried, and weighed.

The experimental area was irrigated to prevent wilt, and it received fertilizer in June, September, and November with an annual total of 2.9 lb N, 0.4 lb P2O5, and 1.1 lb K2O 1000 ft-2 (142 kg N, 20 kg P2O5, and 54 kg K2O ha-1). Diseases were preventatively controlled with appropriate fungicides. Weeds were controlled with postemergence herbicides or by mechanical removal.

Results and DiscussionFor all treatments, mowing when one-third of the leaf blade is removed reduced mowing requirements compared to mowing on a weekly basis (Table 2). The weekly-mown medium and fast-growing tall fescue cultivars had 30 mowing events over a 33-week period from 3/20/12 until 10/30/12. The weekly-mown slow-growing tall fescue cultivar had 29 mowing events over the same period. On the weeks of 6/5/12, 10/16/12, and 10/23/12, no tall fescue cultivars grew the required 0.5 in (1.3 cm) to be mown; additionally, the slow-growing tall fescue didn’t require mowing the week of 10/3/12. All weekly-mown plots received a final mowing on 30 Oct. 2012.

The Kentucky bluegrass cultivars had lower mowing requirements than the tall fescue cultivars across all mowing frequencies and clipping managements, except the fast-growing Kentucky bluegrass (‘Thermal blue’) which was similar to the slow-growing tall fescue when mown using the one-third rule (Table 2). The fast-growing cultivar had the highest mowing requirement amongst the Kentucky bluegrass cultivars used, which was most apparent when mowing frequency was based on the one-third rule. Conversely, the slow-growing Kentucky bluegrass (‘Prosperity’) cultivar had the lowest mowing requirement of any cultivar for either species used in the experiment (Table 2), and the medium-growing Kentucky bluegrass (‘Moonshine’) fell between the slow-growing and fast-growing Kentucky bluegrass cultivars.

Clipping management did not affect the weekly mowing requirement, as all weekly-mown plots

28


within cultivar were the same regardless of clipping management. However, when mowing frequency was based on the one-third rule, returning grass clippings increased the number of annual mowing events by 1-2 mowings for all cultivars except the slow-growing Kentucky bluegrass (Table 2).

For clipping yields, all three tall fescue cultivars had greater cumulative yields than the Kentucky bluegrass cultivars. Both species’ fast-growing cultivars were the highest yielding within species and the slow-growing cultivars were the lowest yielding within species (Fig. 1).

The results from the first year of this experiment indicate that both mowing regime, including mowing frequency and grass clipping management, and turfgrass selection are important in the annual mowing requirement of a turf sward. These results are preliminary and summarize the first of two years of data collection. Next year’s report will include a summary of the two years of data collection and a full statistical analysis of the results.

Acknowledgements: The authors want to express their thanks to the Midwest Regional Turf Foundation and Purdue University for partial funding of this research.

ReferencesBeard, J.B. 1976. Clipping disposal in relation to rotary lawn mowers and the effects on thatch. Journal of the Sports Turf Research Institute 52:85–91.

Christians, N. 2011. Fundamentals of turfgrass management. 4th ed. Wiley. Hoboken, NJ.

Graper, D. and S. Munk. 1994. Cut it high… let it lie. Ext. Extra 6030. South Dakota State University. Brookings, SD.

Haley, J.E., D.J. Wehner, T.W. Fermanian, and A.J. Turgeon. 1985. Comparison of conventional and mulching mowers for Kentucky bluegrass maintenance. HortScience 20:105–107.

Heckman, J.R., H. Liu, W. Hill, M. DeMilia, and W.L. Anastasia. 2000. Kentucky bluegrass responses to mowing practice and nitrogen fertility management. Journal of Sustainable Agriculture 15(4):25–33.

Johnson, B.J., R.N. Carrow, and R.E. Burns. 1987. Bermudagrass turf response to mowing practices and fertilizer. Agronomy J. 79:677–680.

Kopp, K.L., and K. Guillard. 2002. Clipping management and nitrogen fertilization of turfgrass. Crop Sci. 42:1225–1231.

Kopp, K.L., and K. Guillard. 2004. Decomposition rates and nitrogen release of turf grass clippings. Proceedings of the 4th International Crop Science Congress. Brisbane, Queensland, Australia. 26 September - 1 October, 2004.

Madison, J.H. 1962. Mowing of turfgrass. II. Responses of three species of grass. Agronomy Journal 54(3): 250–252.

Starr, J.L., and H.C. DeRoo. 1981. The fate of nitrogen fertilizer applied to turfgrass. Crop Sci. 21:531–536.

Reicher, Z., A.J. Patton, C.A. Bigelow, and T. Voigt. 2006. Mowing, thatching, aerifying, and rolling turf. Purdue University Extension Publication. AY-8-W. West Lafayette, IN.

Reicher, Z., C. Throssell, and R. Lerner. 1994. Don’t bag it! Purdue University Extension Publication. AY-2. West Lafayette, IN.

Wilhelm, W., and C.J. Nelson. 1978. Growth analysis of tall fescue genotypes differing in yield and leaf photosynthesis. Crop Sci. 18:951–954.

29


Table 1. Cultivar, species, and growth rate information for turfgrasses used in this mowing experiment.

Cultivar Experimental # Provider Species Growth rate a

Gazelle II PST-5HP Pure Seed Testing Tall fescue Slow

Tar Heel II PST-5TR1 Pure Seed Testing Tall fescue Moderate

Endeavor PST-5R94E Pure Seed Testing Tall fescue Fast

Prosperity PST-Y2K-59 Pure Seed Testing Kentucky bluegrass Slow

Moonshine PST-1804 Pure Seed Testing Kentucky bluegrass Moderate

Thermal blue HB-129 O.M. Scotts Company Kentucky bluegrass Fast a Cultivars were selected from information on leaf elongation rate provided by Pure Seed Testing.

Table 2. Treatments and the number of recorded mowing events in 2012 in West Lafayette, IN.

Cultivar Species Growth rate a

Mowing events (#)/plot Weekly One-third rule

Collected Returned Collected Returned Gazelle II Tall fescue Slow 29 29 19 21

Tar Heel II Tall fescue Moderate 30 30 20.75 22.5

Endeavor Tall fescue Fast 30 30 23.25 25

Prosperity Kentucky bluegrass Slow 9 9 6 6

Moonshine Kentucky bluegrass Moderate 26 26 14.75 16.75

Thermal blue Kentucky bluegrass Fast 27 27 19.5 21.75 a Cultivars were selected from information on leaf elongation rate provided by Pure Seed Testing.

30


Fig

1. 2

012

cum

ulat

ive

clip

ping

yie

ld fo

r all

six

culti

vars

use

d in

the

expe

rimen

t in

Wes

t Laf

ayet

te, I

N.

050100

150

200

250

300

350

400

450

500 4/3/

2012

5/3/

2012

6/3/

2012

7/3/

2012

8/3/

2012

9/3/

2012

10/3

/201

2

Cumulative Clipping Yield (g/m2)

Dat

e

Slo

w T

F

Med

. TF

Fast

TF

Slo

w K

BG

Med

. KB

G

Fast

KB

G

31

Zac Reicher and Matt Sousek, University of Nebraska LincolnRon Calhoun, Aaron Hathaway, and Jeff Bryan, Michigan State UniversityAaron Patton and Dan Weisenberger, Purdue University

Patton, A., and D. Weisenberger. 2013. Controlling Poa annua on putting green height turf in Indiana, Michigan, and Nebraska: 2012 Research Update. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 32-34.

Summary: Annual bluegrass (Poa annua) is the most troublesome and probably the most studied weed on golf courses throughout the United States. A number of herbicides and growth regulators are labeled and effective for Poa annua control on fairway height turf including bispyribac-sodium (Velocity), ethofumesate (Prograss), flurprimidol (Cutless) and paclobutrazol (Trimmit). As turfgrass extension specialists, we often enter discussions about how to limit or control annual bluegrass on putting greens and how control varies from one location to another. We are evaluating seven season-long treatments of growth regulators or herbicides to control annual bluegrass on putting greens. By completing identical studies at multiple locations that differ widely geographically, we are able to extrapolate our results to a large portion of the United States. The three best treatments improved annual bluegrass control vs. the untreated check 33-37% of the rating dates over multiple locations and three years. Velocity at 2 oz/A applied 4 times, Trimmit, and Cutless were the best performers across all years and locations; however, the results are variable by location. This may help explain the highly variable anecdotal results from superintendents across the country and support the fact that a superintendent may have to experiment to find the best treatment for controlling annual bluegrass at their location.

Additional index words: bispyribac; cumyluron; Cutless; ethofumesate; flurprimidol; paclobutrazol; Primo; Prograss; Trimmit; trinexapac-ethyl; Velocity.

cultural methods for exclusion on new putting greens, we have little confidence in using growth regulators or herbicides on greens north of the transition zone because of labeling issues and the following three reasons:

1. Most of the previous research was done on fairway height bentgrass which is more competitive with annual bluegrass and more tolerant of herbicides or growth regulators (Bigelow et al., 2007; Woosley et al., 2003).

2. Most of the previous plant growth regulator research was done with monthly applications and/or either summer or fall applications, unlike applications made every two weeks with today’s standards (Isgrigg et al., 1999a, 1999b; Johnson and Murphy, 1995, 1996).

3. Most of the putting greens-height research was done in the southeast United States where annual bluegrass is likely more susceptible to control during the warmer summers (Isgrigg et al., 1999a, 1999b; Johnson and Murphy, 1995, 1996; Teuton et al., 2007).

TURFGRASS SCIENCE

Controlling Poa annua on putting green height turf in Indiana, Michigan, and Nebraska:

2012 Research Update

Annual bluegrass (Poa annua) is the most troublesome and probably the most studied weed on golf courses throughout the United States. A number of herbicides and growth regulators are labeled and effective for Poa annua control on fairway height turf including bispyribac-sodium (Velocity), ethofumesate (Prograss), flurprimidol (Cutless) and paclobutrazol (Trimmit, TGR). As turfgrass extension specialists, we often enter discussions about how to limit or control annual bluegrass on putting greens. Outside of the typical

32


Because of these issues, we are evaluating seven season-long treatments of growth regulators or herbicides to control annual bluegrass on putting greens. By completing identical studies at four locations that differ widely geographically, we are able to extrapolate our results to a large portion of the United States.

Materials and Methods

Plots of green-height annual bluegrass/creeping bentgrass were already established on putting greens that are mowed daily at 0.125” and sand-topdressed regularly. The areas receive 2.5 to 3.0 lbs N/1000 ft2/yr. Treatments are applied in 2 gals water/1000 ft2 and are listed in Table 1. Most of these treatments are within label limits with the exception of Velocity, and are based on superintendents and label recommendations as well as previous research experience. Treatment 3 is an experimental herbicide with potential for Poa annua control (Askew et al., 2009). Visual quality and percent cover of creeping bentgrass and annual bluegrass are recorded monthly and transect counts are taken in mid-May and mid-August, the expected high and low points for annual bluegrass populations, respectively. The transect counts minimize subjectiveness between rates and will allow reliable comparisions between years within locations and across locations. This study has been done on the same plots in West Lafayette, IN, and East Lansing, MI, in 2009-2012, Lexington, KY, in 2009-2010, and Lincoln, NE, in 2010-2012.


Annual bluegrass populations are naturally at a seasonal high in April or May, drop to a seasonal low in August and then return to a seasonal high the following spring. Our data show that regardless of treatment, annual bluegrass cover dropped dramatically over the summer to almost insignificant populations. Therefore, one could deduce incorrectly that their control strategy is working if no untreated area for comparison is included on their golf course.

Annual bluegrass control was highly variable from location to location and among years. Though data were recorded on 87 dates over the four locations and four years, treatment differences were only evident on 50 (57%) of the dates. This suggests that regardless of the control regime attempted,

the superintendent will not see any detectable differences on 40% of the days the greens are examined. Therefore if an annual bluegrass control program is attempted, it is critical to manage expectations of the staff and other decision makers who might expect dramatic results.

Velocity at 2 oz/A applied 4 times is the best performing treatment to date, where it decreased annual bluegrass cover compared to the untreated check on 37% of the rating dates (Table 1). The other two treatments that performed similarly to this Velocity treatment were Trimmit that reduced annual bluegrass cover on 33% of the dates and Cutless that reduced annual bluegrass on 30% of the rating dates (Table 1).

Within locations, Trimmit has continued to be the best performer at Purdue and Michigan State, reducing annual bluegrass cover on 33 and 87% of the rating dates, respectively. Velocity applied four times at 2 oz/A and HM9530 are the best performers at University of Nebraska, reducing annual bluegrass cover on 50% of the rating dates. These results not only help explain the highly variable anecdotal results from superintendents across the country, but also suggest that a superintendent may have to experiment to find the best treatment for controlling annual bluegrass on a particular golf course.

Acknowledgements: The authors would like to thank the Midwest Regional Turf Foundation and the United States Golf Association Green Section for partial funding of this research..

References

Askew, S. D., J. B. Willis, M. J. Goddard, and T. L. Mittlestead. 2009. Controlling Annual Bluegrass on Greens and Fairways with HM9930. WSSA Abstracts: 380.

Bigelow, C. A., G. A. Hardebeck, and B. T. Bunnell. 2007. Monthly flurprimidol applications reduce annual bluegrass populations in a creeping bentgrass fairway. Online. Applied Turfgrass Science doi:10.1094/ATS-2007-0508-02-RS.

Isgrigg, J. III, and F. H. Yelverton. 1999a. New approaches to management of annual bluegrass in bentgrass putting greens. Proc Southern Weed Sci. Soc. 52:72.

33


Isgrigg, J. III, and F. H. Yelverton. 1999b. Transition of Poa annua spp reptans infested bentgrass putting greens to monoculture bentgrass using plant growth regulators. Proc. Southern Weed Sci. Soc. 52:76-77.

Johnson, B. J. and T. R. Murphy. 1995. Effect of paclobutrazol and flurprimidol on suppression of Poa annua spp reptans in creeping bentgrass (Agrostis stolonifera) greens. Weed Tech. 10:705-709.

Johnson, B. J. and T. R. Murphy. 1996. Suppression of a perennial subspecies of annual bluegrass (Poa annua spp reptans) in a creeping bentgrass (Agrostis stolonifera) green with plant growth regulators. Weed Tech. 10:705-709.

4

Table 1. Treatments used to control annual bluegrass in identical experiments in three states over 2009-2012. Out of the total 87 rating dates across all locations and years, the best performing treatments reduced annual bluegrass cover on only 37% of the ratings.

Trt Product Rate Application frequency

Application dates

Totalapplications per year

2009-2012 dates where Poa cover

< untreated check

(87 total ratings in 4 states & 4

years)

1 Velocity WSP 1 oz/A 2 wks May-Sep 8 25%

2 Velocity WSP 2 oz/A 2 wks Aug-Sep 4 37%

3 HM9530 130 oz/A 5 mo Apr, Aug 2 23%

4 Trimmit 8 oz/A 16 oz/A

2 wks 2 wks

Apr-May, Aug-Sep

June-July

84 33%

5 Cutless 8 oz/A 16 oz/A

2 wks 2 wks

Apr-May May-Aug

57 30%

6 Legacy 10 oz/A 2 wks Apr-Sep 12 17%

7 Primo 11 oz/A 2 wks Apr-Sep 12 11%

8 Check - - - - 0%

Teuton, T. C., C. L. Main, J. C. Sorochan, J. S. McElroy, and T. C. Mueller. 2007. Annual bluegrass (Poa annua) control in creeping bentgrass (Agrostis stolonifera) putting greens with bispyribac-sodium. Weed Tech. 21:426-430.

Woosley, P. B., D. W. Williams, and A. J. Powell. 2003. Postemergence control of annual bluegrass (Poa annua spp. reptans) in creeping bentgrass (Agrostis stolonifera) turf. Weed Tech. 17:770-776.

34


Patton, A., and D. Weisenberger. 2013. Postemergence Broadleaf Herbicide Safety on Creeping Bentgrass Putting Greens – 2012 Update. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 35-38.

Summary: Few broadleaf weeds can survive on putting greens with the exception of white clover, mouse-ear chickweed, and prostrate spurge. Despite a golf course superintendent’s best efforts and even with the use of sound management practices, weeds other than annual bluegrass do occasionally occur on putting greens. However, many golf course superintendents are hesitant to use herbicides on their putting greens for fear that injury might occur. The objective of this experiment was to determine the safety of postemergence broadleaf herbicides on greens height creeping bentgrass. Applications at label rates did not cause unacceptable injury when applied in May, but 2x rates of 4-Speed XT, Banvel, and Trimec Southern did cause unacceptable injury 2 weeks after application (WAA) that was transient and was acceptable by 3WAA. Mecomec 2.5, Quicksilver, Trimec Bentgrass, and Trimec Classic caused minimal injury when applied at the labeled rate or 2x rate in May. In summary, broadleaf herbicides labeled for putting green use can be safely applied at labeled rates in the spring and fall; 2) injury is more likely to occur from May herbicide applications than those made in October; 3) some herbicides are safer than others with high rates of dicamba, triclopyr, and 2,4-D causing injury; and 4) unacceptable injury can occur from spot applications if herbicides are overdosed.

Additional index words: 2,4-D; 4-Speed; 4-Speed XT; Banvel; carfentrazone; dicamba; Mecomec 2.5; mecoprop (MCPP); pyraflufen-ethyl; Quicksilver T&O; triclopyr; Trimec Bentgrass; Trimec Classic; Trimec Encore; Trimec Southern.

other than annual bluegrass do occasionally occur on putting greens. However, many golf course superintendents are hesitant to use herbicides on their putting greens for fear that injury might occur. The objective of this experiment was to determine the safety of postemergence broadleaf herbicides on greens height creeping bentgrass.

Materials and MethodsThe experiment was conducted at the W.H. Daniel Turfgrass Research and Diagnostic Center in West Lafayette, IN. The location was a ‘Pennlinks’ creeping bentgrass putting green grown on a USGA specification sand rootzone. Experimental design was randomized complete block with three replications and an individual plot size of 25 ft2. Plots were mown at 0.135 inches daily. Herbicides included in this study are summarized in Table 1 and they were applied at the putting green label rate and at a rate 2x the label rate. Plots were treated with herbicide 22 May 2012. Herbicides were applied in 40 gpa water with a CO2-pressurized sprayer at 30 psi. An untreated check was included for comparison. Injury to creeping bentgrass was rated on a 9 to 1 scale with 9 = no injury, 7 =

TURFGRASS SCIENCE

Postemergence Broadleaf Herbicide Safety on Creeping Bentgrass Putting Greens –

2012 Update

Few herbicides or plant growth regulators are needed on golf course putting greens to control weeds with the exception of annual bluegrass (Poa annua). This is due to the fact that few broadleaf weeds can survive these low mowing heights with the exception of white clover, mouse-ear chickweed, and prostrate spurge. Crabgrass and goosegrass are problematic grassy weeds that can also occur in putting greens, especially in southern Indiana and the transition zone. Despite a golf course superintendent’s best efforts and even with the use of sound management practices, weeds

35


acceptable injury, and 1 = completely brown turf. Turf quality was visually rated using a scale of 9 to 1 with 9 = best quality, 7 = acceptable quality, and 1 = totally brown and/or bare plot. Data were analyzed using SAS (SAS Institute, Inc). Means were separated using Fisher’s protected least significant difference when F tests were significant at α=0.05.


Results from fall 2011 testing suggested that broadleaf herbicides labeled for putting green use can be safely applied in the fall without fear of causing unacceptable injury (Patton and Weisenberger, 2012). We repeated the experiment in May 2012 to determine if more injury might be expected from late spring and summer applications during warmer temperatures. Average high temperatures were 24 °F warmer for a two-week period following the May application than for a 5 week period following the October application. The average high temperature for the two-week period following the May application was 81 °F. More injury was observed from May 2012 applications than Oct 2011 applications due to warmer temperatures. Applications at label rates did not cause unacceptable injury when applied in May, but 2x rates of 4-Speed XT, Banvel, and Trimec Southern did cause unacceptable injury 2 weeks after application (WAA)(Table 2) that was transient and was acceptable by 3WAA (data not shown). Mecomec 2.5, Quicksilver, Trimec Bentgrass, and Trimec Classic caused minimal injury (≥8.0) when applied at the labeled rate or 2x rate in May (Table 2). These data are supported by reports on the safe use of carfentrazone on creeping bentgrass for silvery thread moss (Bryum argenteum) control (Thompson et al., 2011) and use of Trimec Bentgrass for lesser swinecress (Croronopus didymus) control (Straw et al., 2012).

In summary (2011 and 2012 reports), broadleaf herbicides labeled for putting green use can be safely applied at labeled rates in the spring and fall; 2) injury is more likely to occur from May herbicide applications than those made in October; 3) some herbicides are safer than others with high rates of dicamba, triclopyr, and 2,4-D causing injury; and 4) unacceptable injury can occur from spot applications if herbicides are overdosed.

Acknowledgements:

The authors want to express their thanks to the Midwest Regional Turf Foundation for partial funding of this research.

References

Patton, A.J., and D.V. Weisenberger. 2012. Postemergence broadleaf herbicide safety on putting greens. 2011 Annual Report - Purdue University Turfgrass Science Program. Available at: http://www.agry.purdue.edu/turf/report/2011/PDF/13_AGRY_Patton_prosemergencePuttingGreen.pdf

Straw, C., G. Henry, T. Williams, T. Cooper, and L. Beck. 2012. Postemergence control of lesser swinecress in creeping bentgrass putting greens. Paper presented at: Visions for a Sustainable Planet, ASA, CSSA, and SSSA Annual Meetings, Cincinnati, OH. 21-24 Oct. 2012. Paper 105-7.

Thompson, C., Fry, J., and Kennelly, M. 2011. Evaluation of conventional and alternative products for silvery-thread moss control in creeping bentgrass. Online. Applied Turfgrass Science doi:10.1094/ATS-2011-1018-01-RS.

36


4

Tabl

e 1.

Bro

adle

af h

erbi

cide

s la

bele

d fo

r cre

epin

g be

ntgr

ass

putti

ng g

reen

s.

Trad

e N

ame

(pro

duct

/Acr

e)

Ingr

edie

nts

(am

ount

of a

.i. o

r a.

e./A

in

pare

nthe

ses)

La

bel r

ate/

Acr

e La

bel L

angu

age

Labe

l Com

men

ts

App

licat

ion

Volu

me

(gal

/A)

4-Sp

eed

2,4-

D (0

.5) +

MC

PP

(0

.13)

+ d

icam

ba

(0.0

5) +

pyr

aflu

fen

ethy

l (0.

001)

1.8

pint

P

uttin

g an

d B

owlin

g G

reen

s A

void

app

licat

ions

dur

ing

perio

ds w

hen

turf

is u

nder

stre

ss d

ue to

hi

gh h

eat,

hum

idity

, and

redu

ced

moi

stur

e. S

light

turf

yello

win

g w

ill d

isap

pear

afte

r abo

ut o

ne w

eek.

43 to

87

4-Sp

eed

XT

2,4-

D (0

.5) +

tri

clop

yr (0

.06)

+

dica

mba

(0.0

6) +

py

raflu

fen

ethy

l (0

.001

)

1.8

pint

P

uttin

g an

d B

owlin

g G

reen

s A

void

app

licat

ions

dur

ing

perio

ds w

hen

turf

is u

nder

stre

ss d

ue to

hi

gh h

eat,

hum

idity

, and

redu

ced

moi

stur

e. S

light

turf

yello

win

g w

ill d

isap

pear

afte

r abo

ut o

ne w

eek.

43 to

87

Ban

vel

dica

mba

(0.5

) 1

pint

B

entg

rass

La

bel n

eith

er a

llow

s no

r res

trict

s ap

plic

atio

ns to

put

ting

gree

ns.

Use

1 p

int o

r les

s of

pro

duct

per

acr

e. D

o no

t use

on

bent

gras

s un

less

pos

sibl

e cr

op in

jury

can

be

tole

rate

d. [A

utho

r not

e: w

eeds

ca

n be

con

trolle

d w

ith a

s lit

tle a

s 4

fl oz

/acr

e w

ith th

is h

erbi

cide

]

3 to

50

Mec

omec

2.5

m

ecop

rop-

p (M

CP

P)

(1.2

5)

4 pi

nt

Est

ablis

hed

Gre

ens

Use

onl

y on

act

ivel

y gr

owin

g tu

rf th

at is

not

und

er s

tress

. Do

not

appl

y to

ben

tgra

ss in

the

heat

of s

umm

er.

22 to

174

Qui

cksi

lver

T&

O

carfe

ntra

zone

(0.1

) 6.

7 oz

G

olf C

ours

e G

reen

s Q

uick

silv

er (c

arfe

ntra

zone

) T&

O 1

.9E

C a

t 2.0

to 6

.7 o

z pe

r acr

e w

hen

tem

pera

ture

s ar

e le

ss th

an 8

5 F

pro

vide

s ex

celle

nt m

oss

cont

rol.

App

ly a

s of

ten

as e

very

two

wee

ks to

put

ting

gree

ns

infe

sted

with

silv

ery

thre

ad m

oss.

Ann

ual b

lueg

rass

can

be

dam

aged

at r

ates

gre

ater

than

2.0

oz

Qui

cksi

lver

T&

O 1

.9E

C p

er

acre

. Use

a n

on-io

nic

surfa

ctan

t at 0

.25%

v/v

. Do

not a

pply

to

bent

gras

s w

hen

tem

pera

ture

s ex

ceed

90 F

.

20 to

175

Trim

ec B

entg

rass

m

ecop

rop

(0.2

4) +

2,

4-D

(0.1

5) +

di

cam

ba (0

.06)

2.7

pint

P

uttin

g an

d B

owlin

g G

reen

s D

o no

t app

ly to

ben

tgra

ss u

nder

stre

ss. D

o no

t app

ly w

hen

air

tem

pera

ture

s ex

ceed

85°

F. M

ay o

r fal

l app

licat

ion

reco

mm

ende

d.

high

Trim

ec C

lass

ic

2,4-

D (0

.45)

+

mec

opro

p (0

.12)

+

Dic

amba

(0.0

5)

1.8

pint

P

uttin

g an

d B

owlin

g G

reen

s D

o no

t exc

eed

1.0

fl oz

/1,0

00 ft

2 on

cree

ping

ben

tgra

ss p

uttin

g gr

eens

usi

ng a

spr

ay v

olum

e of

5 g

allo

ns/1

000

ft2 . Do

not a

pply

to

ben

tgra

ss u

nder

stre

ss. D

o no

t app

ly w

hen

air t

empe

ratu

res

exce

ed 8

5° F

.

145

Trim

ec E

ncor

e M

CP

A (0

.67)

+

mec

opro

p (0

.14)

+

dica

mba

(0.0

7)

1.8

pint

P

uttin

g an

d B

owlin

g G

reen

s D

o no

t exc

eed

1.0

fl oz

/1,5

00 ft

2 on

cree

ping

ben

tgra

ss p

uttin

g gr

eens

usi

ng a

spr

ay v

olum

e of

5 g

allo

ns/1

000

ft2 . Do

not a

pply

to

ben

tgra

ss u

nder

stre

ss. D

o no

t app

ly w

hen

air t

empe

ratu

res

exce

ed 8

5° F

. Slig

ht y

ello

win

g w

ill o

ccur

with

in a

wee

k.

145

Trim

ec S

outh

ern

mec

opro

p (0

.33)

+

2,4

-D (0

.36)

+

dica

mba

(0.0

7)

2.0

pint

B

entg

rass

U

se 2

.0 p

ints

of p

rodu

ct p

er a

cre.

Do

not o

verd

ose

clos

ely-

mow

ed b

entg

rass

. Ber

mud

agra

ss a

nd b

entg

rass

are

mod

erat

ely

sens

itive

to 2

,4-D

.

2 to

300

37


5

Table 2. Injury ratings following applications of broadleaf herbicides to a creeping bentgrass putting green on 22 May 2012 in Indiana at label and 2x label application rates. Only a portion of the data collected is shown for brevity. The data shown represents the date with maximum injury.

Herbicide Rate/A Creeping bentgrass injury 2 weeks after application

-------1 to 9 a -------4-Speed 1.8 pint b 7.3 bcd c 4-Speed XT 1.8 pint b 8.0 abc Banvel 1.0 pint b 8.3 ab Mecomec 2.5 4.0 pint b 9.0 a Quicksilver T&O 6.7 fl oz b d 9.0 a Trimec Bentgrass 2.7 pint b 9.0 a Trimec Classic 1.8 pint b 8.7 a Trimec Encore 1.8 pint b 8.3 ab Trimec Southern 2.0 pint b 8.3 ab 4-Speed 3.6 pint e 7.0 cde 4-Speed XT 3.6 pint e 6.7 def Banvel 2.0 pint e 6.0 ef Mecomec 2.5 8.0 pint e 8.0 abc Quicksilver T&O 13.4 fl oz d e 9.0 a Trimec Bentgrass 5.4 pint e 8.7 a Trimec Classic 3.6 pint e 8.0 abc Trimec Encore 3.6 pint e 7.3 bcd Trimec Southern 4.0 pint e 5.6 f Untreated 9.0 a P-value <0.0001

a Turf injury was rated on a 1-9 scale where 1=completely brown turf, 9= no injury, and ≥7=acceptable injury. b Label rate for putting green applications. c Means followed by the same letter within each column are not significantly different. Means were separated using Fisher's protected least significant difference (=0.05). d Application included a nonionic surfactant at 0.25% (v/v). e Twice the maximum allowable putting green label rate (2x).

38


Patton, A., and D. Weisenberger. 2013. Postemergence Broadleaf Herbicide Safety on Creeping Bentgrass Putting Greens – 2012 Update. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 39-41.

Summary: Crabgrass (Digitaria spp.) is often considered to be the most problematic weed in lawns. Crabgrass is a summer annual grassy weed that typically germinates in April in the Midwest. The best approach to controlling crabgrass is using a preemergence herbicide such as dithiopyr (Dimension), pendimethalin (Pendulum), prodiamine (Barricade), sulfentrazone + prodiamine (Echelon), and others. The objective of this experiment was to evaluate Quali-Pro’s new post-patent dithiopyr liquid formulation and compare that formulation to other preemergence herbicides for efficacy of crabgrass. All treatments performed better than the check on all rating dates. Quali-Pro Dithiopyr 2L provided the same reduction in crabgrass cover as Dimension 2EW, QP Dithiopyr 40 WP, Pendulum Aqua Cap 3.8L, and QP Prodiamine. These results verify that consistent preemergence crabgrass control can be achieved with numerous products including the post-patent products in this experiment. While no differences occurred between single and split (sequential) applications in this experiment, our recommendation is to use a split application strategy for preemergence herbicide applications to enhance crabgrass control.

Additional index words: dithiopyr, pendimethalin, preemergence, prodiamine.

in certain “hot spots” such as next to sidewalks and driveways as well as sunny areas. The best approach to controlling crabgrass is using a preemergence herbicide such as dithiopyr (Dimension), pendimethalin (Pendulum), prodiamine (Barricade), sulfentrazone + prodiamine (Echelon), and others. These herbicides inhibit cell division and prevent crabgrass seeds from properly emerging. Since these herbicides work on germinating seeds, they must be applied prior to germination with the exception of dithiopyr which controls crabgrass before and after germination until it reaches one tiller. The objective of this experiment was to evaluate Quali-Pro’s new post-patent dithiopyr liquid formulation and compare to other preemergence herbicides for efficacy of crabgrass.

Materials and MethodsThe experiment was conducted at the W.H. Daniel Research and Diagnostic Center in West Lafayette, IN. The site was a Kentucky bluegrass blend with a uniform cover by crabgrass. Experimental design was randomized complete block with three replications and an individual plot size of 25 ft2. Plots were mown at 2 inches as needed. Plots were

TURFGRASS SCIENCE

Evaluation of Crabgrass Control with Various Preemergence Herbicides - 2012

Large crabgrass (Digitaria sanguinalis) and smooth crabgrass (Digitaria ischaemum) are both species of crabgrass found in the Midwest that are collectively referred to as crabgrass. Crabgrass is often considered to be the most problematic weed in lawns (Patton and Weisenberger, 2013). Crabgrass is a summer annual grassy weed that typically germinates in April in the Midwest (early April in southern areas and late-April in northern areas). Proper mowing (higher mowing heights), proper fertilization (some rather than none to improve turf density), irrigation to prevent summer dormancy during drought, and aerification of compacted areas to improve turf health are all cultural practices that can be used to reduce crabgrass. Despite proper cultural practices, crabgrass may still remain problematic

39


treated with herbicides on 22 March and 23 May 2012. Herbicides were applied in 87 gpa water with a CO2-pressurized sprayer at 30 psi. An untreated check was included for comparison. Crabgrass coverage was visually rated as percent crabgrass coverage. Kentucky bluegrass phytotoxicity was rated on a scale of 9 to 1 were 9 equaled no phytotoxicity, 7 equaled acceptable damage, and 1 equaled completely brown turf. All data were analyzed using SAS (SAS Institute, Inc). Means were separated using Fisher’s protected least significant difference when F tests were significant at α=0.05.

Results and DiscussionAll treatments performed better than the check on all rating dates (Table 1). There was no phytotoxicity to the Kentucky bluegrass from any treatment in this study. Quali-Pro Dithiopyr 2L provided the same reduction in crabgrass cover as Dimension 2EW and the same as QP Dithiopyr 40 WP in our experiment when applied as a single application at 0.5 lb ai/A or when applied as a split application of 0.25 + 0.25 lb ai/A (Table 1). Quali-Pro Dithiopyr 2L also performed similar to Pendulum Aqua Cap 3.8L applied as a single application (3.0 lbs ai/A) or as a split application (1.5 + 1.5 lbs ai/A) and QP Prodiamine applied as a single application (0.75 lb ai/A) or as a split application (0.38 + 0.38 lbs ai/A)(Table 1).

These results verify that consistent preemergence crabgrass control can be achieved with numerous products including the post-patent products in this experiment. While no differences occurred between single and split (sequential) applications in this experiment, our recommendation is to use a split application strategy for preemergence herbicide applications to enhance crabgrass control (Patton et al., 2012).

ReferencesPatton, A., D. Weisenberger, and Z. Reicher. 2012. Sequential applications of preemergence crabgrass herbicides for enhanced control – three year summary. 2011 Annual Report - Purdue University Turfgrass Science Program. Available at: http://www.agry.purdue.edu/turf/report/2011/PDF/15_AGRY_Patton_sequential%20apps.

pdf

Patton, A.J. and D.V. Weisenberger. 2013 Turfgrass Weed Control for Professionals. Purdue University Extension Publication. AY-336. 2nd revision.

40


Table 1. Crabgrass coverage following various herbicide applications in the spring. Initial applications were made 22 March with sequential applications made 23 May.

Crabgrass coverage

Herbicide Rate 31 May 2 July 1 Aug 30 Aug

lb ai/A %

Untreated 2 a a 30 a 87 a 96 a Quali-Pro Dithiopyr 2L 0.25 0 b 1 b 6 bc 8 bc fb b Quali-Pro Dithiopyr 2L 0.25 Quali-Pro Dithiopyr 2L 0.5 0 b 1 b 4 bc 10 bc Quali-Pro Dithiopyr 40WP 0.25 0 b 0 b 1 c 3 c fb Quali-Pro Dithiopyr 40WP 0.25 Quali-Pro Dithiopyr 40WP 0.5 0 b 1 b 2 c 6 bc Quali-Pro Prodiamine 65WDG 0.75 0 b 1 b 4 bc 10 bc Quali-Pro Prodiamine 4L 0.75 0 b 1 b 2 c 4 c Quali-Pro Prodiamine 4L 0.38 0 b 2 b 8 bc 13 bc fb Quali-Pro Prodiamine 4L 0.38 Dimension 2EW 0.25 0 b 1 b 3 c 8 bc fb Dimension 2EW 0.25 Dimension 2EW 0.5 0 b 1 b 8 bc 10 bc Pendulum Aquacap 3.8L 3 0 b 1 b 4 bc 8 bc Pendulum Aquacap 3.8L 1.5 0 b 2 b 12 b 18 b fb Pendulum Aquacap 3.8L 1.5

P-value 0.0051 <0.0001 <0.0001 <0.0001

a Means followed by the sample letter are not significantly different. b fb = “followed by” sequential application on 23 May after the initial application on 22 March.

41


Patton, A., and D. Weisenberger. 2013. Herbicide Efficacy on Wild Violet – Greenhouse Experiments. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 42-47.

Summary: Wild violet (Viola spp.) is a persistent perennial and difficult to control broadleaf weed. Cultural practices have little impact on wild violet populations and turf managers rely on herbicides for control. Most herbicides provide intermediate to poor violet control, although applications of triclopyr or tank-mixtures of 2,4-D and triclopyr reportedly provide excellent control. The objectives of this experiment were to 1) determine which herbicides (2,4-D amine; 2,4-D ester; 2,4-DP; MCPA; MCPP; quinclorac; and triclopyr) and herbicide combinations most effectively control wild violet, and 2) determine what rate of triclopyr is needed for control. Triclopyr provided the greatest wild violet efficacy in our experiment. The rate experiment demonstrated that ≥0.75 lbs ae/A triclopyr provides the best wild violet control. Treatments containing triclopyr were not different from the triclopyr treatment alone, indicating that there were no additive effects or synergism between the herbicide combinations we tried in our experiment.

Additional index words: 2,4-D amine; 2,4-D ester; 2,4-DP; Drive, MCPA; MCPP; mecoprop; quinclorac; triclopyr; Turflon Ester Ultra; Viola.

Excellent control of wild violet is possible from applications of triclopyr (Hurto et al. 1984; Witt et al. 1986). 2,4-D alone is reported to provide fair control (Jagachitz and Sawyer, 1987), but when tank-mixed with triclopyr it can effectively reduce the cover of wild violet (Vrabel et al., 1987). The objectives of this experiment were to 1) determine which herbicides and herbicide combinations most effectively control wild violet, and 2) determine what rate of triclopyr is needed for control.

Materials and MethodsTwo experiments were conducted at the Purdue University, Life Sciences Greenhouses. The first experiment looked at the efficacy of various herbicides and the second experiment looked at a range of triclopyr rates to determine the rate needed to achieve control.

Violets (Viola sororia) were collected in October and November 2011 from a residence in Lafayette, IN and immediately transported to the greenhouse. The plants were transplanted into 10 cm diameter pots filled with a silt loam soil. The violets were fertilized monthly and watered daily until the initiation of the experiments.

The herbicide efficacy experiment was conducted twice with the applications being made on 18 April and 29 May, 2012. Treatments included 2,4-D

TURFGRASS SCIENCE

Herbicide Efficacy on Wild Violet – Greenhouse Experiments

Wild violet (Viola spp.) is a persistent perennial and difficult to control broadleaf weed. The Midwest species often referred to as wild violet by turf managers include common blue violet (Viola sororia), wooly blue violet (Viola papilionacea), and confederate violet (Viola sororia f. priceana). Cultural practices such as proper mowing, fertilization, and irrigation can be manipulated to control some weed species but these practices have little impact on wild violet populations. Wild violet can be decreased by more frequent mowing but not by fertilization (Gray and Call, 1993). It is unknown how irrigation, drainage, and soil compaction influence wild violet populations. As such, turf managers rely on herbicides to control wild violet.

There is limited literature, with some being outdated, that lists active ingredients for wild violet control. Most of the active ingredients are listed as providing intermediate to poor control.

42


amine (1 lb ae/A); 2,4-D ester (1 lb ae/A); MCPA (1 lb ae/A); MCPP (1 lb ae/A); 2,4-DP (1 lb ae/A); triclopyr (1 lb ae/A); quinclorac (0.75 lb ae/A); triclopyr (1 lb ae/A) + quinclorac (0.75 lb ae/A); 2,4-D ester (1 lb ae/A) + 2,4-DP (1 lb ae/A); 2,4-D ester (1 lb ae/A) + triclopyr (1 lb ae/A); 2,4-D ester (1 lb ae/A) + 2,4-DP (1 lb ae/A) + triclopyr (1 lb ae/A); and an untreated check. The herbicides were applied in 87 gal/A water at 30 psi with CO2 pressurized boom sprayer equipped with an XR80015VS flat-fan nozzle. The pots were arranged in a randomized complete block design on the greenhouse bench. Data collected were percent epinasty, percent necrosis, chlorophyll content index (CCI), and dry matter yield following regrowth.

The triclopyr rate experiment was conducted twice with the applications being made on 29 May and 7 September 2012. Treatments included triclopyr at 0, 0.125, 0.25, 0.5, 0.75, and 1.0 lb ae/A. The herbicides were applied in the same manner as the efficacy experiment and the experimental design and data collection were also similar. The data from both experiments were analyzed in SAS. The epinasty, CCI, and regrowth data could be combined over experimental runs in each experiment. Regression analysis for the rate experiment was performed with SigmaPlot.

Results and DiscussionEfficacy experiment:At 7 days after application (DAA) all treatments containing triclopyr and the quinclorac treatment had the lowest CCI values ranging from 3.3 to 4.2 compared to 2,4-D ester (6.2) and the untreated check (6.0) (Table 1). Other rating dates showed similar rankings among treatments. Epinasty ranged from 71 to 89 percent 14 DAA for triclopyr containing treatments (Table 1) but was <25% for all other treatments (Table 1).

By 42 DAA all treatments containing triclopyr had necrosis ratings ranging from 80 to 96 percent in run 1 and 58 to 80 percent in run 2 (Table 1). Comparatively, necrosis ratings for other treatments ranged from 8 to 25, at 42 DAA. Regrowth 42 days after harvest for treatments containing triclopyr ranged from 0.02 g to 0.15 g dry tissue and were lower than all other treatments that had values ranging from 0.46 g to 0.62 g dry tissue (Table 1).

Rate experiment:The triclopyr rate experiment showed similar trends regardless of data collection type. As triclopyr rate increased, violet epinasty (Fig. 1) and necrosis (Fig. 2) increased while CCI (Fig. 3) and biomass (Fig. 4) decreased. In our experiment, triclopyr applied at 0.75 and 1.0 lbs ae/A (equal to 0.84 kg ae/ha and 1/12 kg ae/ha, respectively) provided the best efficacy and typically provided similar levels of control. Many turf herbicides containing triclopyr are available to turf professionals but most apply ≤0.5 lb ae/A triclopyr when applied at the high label rate (Table 2). Thus, to improve violet control, turf managers should apply triclopyr by itself at 0.75 to 1.0 lbs ae/A (this is equivalent to 1.5 to 2.0 pts/A Turflon Ester Ultra) or tank-mix 0.5 lb ae/A triclopyr (this is 1.0 pint/A Turflon Ester Ultra, which is the maximum label allowable amount when tank-mixing) with another triclopyr containing herbicide.

DiscussionTriclopyr provided the greatest wild violet control of all the herbicides tested in our efficacy experiment. Treatments containing triclopyr were not different from the triclopyr treatment alone, indicating that there were no additive effects or synergism between the herbicide combinations we tried in our experiment. The rate experiment demonstrated that ≥0.75 lbs ae/A triclopyr provides the best wild violet control. Herbicides available to turf managers that apply ≥0.75 lbs ae/A at labeled rates include Tailspin, Turflon Ester Ultra, and Triclopyr 4.

Acknowledgements: The authors want to express their thanks to the Midwest Regional Turf Foundation for partial funding of this research.

43


ReferencesGray, E. and N. M. Call. 1993. Fertilization and mowing on persistence of Indian mockstrawberry (Duchesnea indica) and common blue violet (Viola papilionacea) in a tall fescue (Festuca arundinacea) Lawn. Weed Science. Volume 41:548-550.

Hurto, K. A., M. J. Thielen and M.M. Mahady. 1984. Postemergence activity of Triclopyr for broadleaf weed control in turf. In 1984 Agronomy Abstracts. ASA, Madison, WI. November 1984, p. 151.

4

Table 1. Chlorophyll content, percent epinasty, percent necrosis, and regrowth of wild violet (Violasororia) following herbicide applications. Data was collected 7, 14, 21, 28, 35, and 42 days after application (DAA) and regrowth data 84 DAA. Where possible, data was combined across experimental runs. For brevity, only a portion of the data is shown. CCI Epinasty Necrosis RegrowthHerbicide Rate 7 DAA 14 DAA 42 DAA-Run 1 42 DAA-Run 2 84 DAA

chlorophyll index % % % g

2,4-D amine 1.0 lb ae/A 4.9 bcd a 15 b 8 c 14 c 0.57 a 2,4-D ester 1.0 lb ae/A 6.2 a 4 b 14 c 25 c 0.52 a 2,4-DP 1.0 lb ae/A 6.1 a 3 b 8 c 13 c 0.46 a MCPP 1.0 lb ae/A 5.6 abc 11 b 15 c 14 c 0.62 a MCPA 1.0 lb ae/A 4.6 cdef 1 b 8 c 14 c 0.48 a quinclorac 0.75 lb ai/A 4.2 defg 26 b 36 b 24 c 0.55 a triclopyr 1.0 lb ae/A 3.9 efg 75 a 96 a 58 b 0.02 b

2,4-D + 2,4-DP 1.0 lb ae/A+1.0 lb

ae/A 4.8 cde 4 b 8 c 20 c 0.53 a triclopyr + quinclorac

1.0 lb ae/A+1.0 lb ai/A 3.4 g 89 a 80 a 70 ab 0.03 b

triclopyr + 2,4-D 1.0 lb ae/A+1.0 lb

ae/A 3.7 fg 71 a 93 a 80 a 0.11 b triclopyr + 2,4-D + 2,4-DP

1.0 lb ae/A+1.0 lb ae/A +1.0 lb ae/A 3.3 g 82 a 88 a 61 b 0.15 b

untreated 6.0 ab 0 b 8 c 18 c 0.50 a a Within columns, means followed by the same letter are not different (LSD, =0.05).

Jagschitz, J. A. and C. D. Sawyer. 1987. Postemergence Control of spurge, violet and oxalis in turf. Proceedings of the 1987 Annual Meeting of the Northeastern. Vol. 41, January 1987, p. 238-239.

Vrabel, T. E. 1987. Wild violet control in cool season turf. Proceeding of 41st Annual Meeting of the Northeastern Weed Science Society. Vol. 41, January 1987, p.237.

Witt, W.W., A.J. Powell, and L. Tapp. 1986. Control of wild violets in turf. Kentucky Turfgrass Research. P. 48-53.

44


5

Table 2. Active ingredients in commonly used turf herbicide combinations with triclopyr. This table only shows triclopyr containing herbicides with more than one ingredient and triclopyr only herbicides. This table compares ingredients and allows users to quickly search for products that contain a particular ingredient. Each cell shows the amount of active ingredient at the low and high label rates in pounds of acid equivalent per acre.

Herbicides 2,4-

D

dica

mba

MC

PA

tric

lopy

r

clop

yral

id

fluro

xypy

r

sulfe

ntra

zone

pyra

flufe

n et

hyl

4-Speed XT 0.5-1.1 0.06-0.14 0.06-0.14 0.001-0.003

Battleship III 0.7-1.4 0.07-0.15 0.07-0.14

Chaser 0.5-1.0 0.25-0.5

Chaser 2 amine 0.7-1.4 0.27-0.54

Confront, 2-D 0.28-0.56 0.09-0.19

Cool Power, Three-way Ester II 0.09-0.13 0.9-1.3 0.09-0.13

Horsepower, Eliminate 0.10-0.14 1.0-1.4 0.10-0.14

Momentum FX2 0.8-1.1 0.1-0.13 0.10-0.14

Tailspin 0.38-0.75 0.12-0.24

Turflon Ester Ultra, Triclopyr 4 0.5-1.0

Turflon II amine 0.9-1.2 0.33-0.47

TZONE 0.4-0.9 0.05-0.10 0.13-0.25 0.02-0.03

45


6

triclopyr (kg ae/ha)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Epi

nast

y (%

), 21

day

s af

ter a

pplic

atio

n

0

20

40

60

80

100

Fig. 1. Regression of percent epinasty 21 days after application, triclopyr rate. Metric units are shown. 1.0 lb ae/A = 1.12 kg ae/ha.


0.0 0.2 0.4 0.6 0.8 1.0 1.2

Nec

rosi

s (%

), 35

day

s af

ter a

pplic

atio

n

0

20

40

60

80

100

Fig. 2. Regression of percent necrosis 35 days after application, triclopyr rate. Metric units are shown. 1.0 lb ae/A = 1.12 kg ae/ha.

P=0.0010, R2=0.95

P=0.0017, R2=0.93

46


7


0.0 0.2 0.4 0.6 0.8 1.0 1.2

Chl

orop

hyll

cont

ent i

ndex

, 28

days

afte

r app

licat

ion

0

1

2

3

4

5

Fig. 3. Regression of chlorophyll content index 28 days after application, triclopyr rate. Metric units are shown. 1.0 lb ae/A = 1.12 kg ae/ha.


0.0 0.2 0.4 0.6 0.8 1.0 1.2

Abo

vegr

ound

bio

mas

s (g

)55

(run

1) o

r 42

(run

2) d

ays

afte

r app

licat

ion

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

run 1run 2

Fig. 4. Regression of above ground biomass 42 days after application, triclopyr rate. Metric units are shown. 1.0 lb ae/A = 1.12 kg ae/ha.

P=0.03, R2=0.72

P<0.0001, R2=0.99

P=0.0007, R2=0.96

47

Douglas S. Richmond, Timothy J. Gibb and Anderson J. Seiter. Department of Entomology , Purdue University.

Summary: Aside from providing excellent control of white grubs, Acelepryn has been widely marketed for use against a number of other turfgrass insect pests. We conducted this study to further explore how application rate influences the efficacy of this product against billbugs in Indiana.

billbug larval/pupal densities was examined using main effects ANOVA and treatment means were compared using Fisher’s LSD test (α=0.05). Billbug species composition at the site consisted mainly of Sphenophorus parvulus with S. minimus and S. inaequalis also being present.

Field conditions on the May 7 treatment date were:(1) Soil Temp.: 17°C(2) Air Temp: 17°C(3) Weather: overcast, wind 0-10 mph(4) Thatch: 2.0 cm

Results and DiscussionAlthough both Merit and the highest rate of Acelepryn provided acceptable levels of billbug control, Meridian provided the highest level of control (table 1). The efficacy of Acelepryn appeared to decrease as application rate decreased.

TURFGRASS SCIENCE

Influence of Application Rate on the Efficacy of Acelepryn Against Bluegrass

Billbug in Kentucky Bluegrass Turf 2012

Materials and MethodsThe experiment was located at the Daniel Center for Turfgrass Research and Diagnostics, Purdue University (West Lafayette, IN) on a stand of turfgrass consisting primarily of Kentucky bluegrass maintained at 7.6 cm (Fig. 1). Plots measuring 2.4 x 2.4 meters were arranged in a randomized complete-block design with 0.3 meter alleys between plots. Treatments were applied on May 7 and were followed by ¼” of rainfall almost immediately after application. Each treatment was replicated 4 times. All materials were applied using a hand-held CO2 boom sprayer configured with four 8010 nozzles operating at 30 psi and calibrated to deliver a spray volume of 2 gal/1000ft2. The combined density of billbug larvae, and pupae was determined on July 10 using a golf course cup cutter to remove 5 cores (4.25” diameter) from each plot to a depth of 3”. The soil and thatch in each core was carefully examined for all billbug life stages and the number of billbugs in each core was recorded (Fig. 2). Variation in

2

Table1.Numberofbillbugspersquarefoot(±SE)and%controlinplotsofKentuckybluegrassturftreatedwithvariousratesofAcelepryncomparedtoMeritandMeridian.WestLafayette,Indiana2012.

Product Application Rate(Product/Acre)

Billbugs/ft2

(Mean±SE) % Control

Acelepryn 1.67SC 4.0 fl.oz. 12.8±1.4 b 45.1

Acelepryn 1.67SC 6.0 fl.oz 8.3±2.3 ab 64.5

Acelepryn 1.67SC 8.0 fl.oz 6.0±1.2 ab 74.2

Merit 75WP 6.4 oz. 5.3±2.3 ab 77.3

Meridian 25 WG 8.6 oz. 1.5±0.9 a 93.5

Untreated ‐‐‐ 23.3±4.1 c ‐‐‐ * Values within a column followed by different letters are significantly different (α=0.05)

48


3

Figure1.Siteofbillbugtrial2012,showingtypicalsymptomsofbillbugdamageduringearlyJuly.W.H.DanielCenterforTurfgrassResearchandEducation,PurdueUniversity,WestLafayette,IN.

4

Figure2.BillbuglarvarecoveredfrommaceratedKentuckybluegrassplantcrownwhileevaluatingplots(July10,2012).

Richmond, D., T. Gibb and A. Seiter. 2013. Influence of Ap-plication Rate on the Efficacy of Acelepryn Against Blue-grass Billbug in Kentucky Bluegrass Turf 2012 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 48-49.

Additional index words: Chlorantraniliprole, Insecticide

49

Timothy J. Gibb, Douglas S. Richmond and Anderson J. Seiter. Department of Entomology , Purdue University.

Gibb, T., D. Richmond and A. Seiter. 2013. Residual Activ-ity of Meridian 25WG and Two Rates of Acelepryn 1.67SC Against Second and Third Instar Black Cutworm Larvae on Creeping Bentgrass Turf 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 50-51.

Summary: The residual activity of chloronicotinyl and anthranilic diamide insecticides may create opportunities to achieve extended control of certain insect pests with only one application. This study examined the residual activity of Meridian 25WG and Acelepryn 1.67SC against second and third instar black cutworm larvae on creeping bentgrass turf maintained under normal putting green management regimes of fertilization, mowing and irrigation.

Additional index words: Chlorantraniliprole, Thiamethoxam, Caterpillar

On each assessment date (Aug, 6th, 13th, 20th, Sept 4th and 17th) cutworms were flushed from the turf using a standard soapy water flushing solution. Larvae emerging from each plot were collected into vials containing 70% ethanol as a preservative. All larvae were then taken to the laboratory where they were counted and weighed.Treatment effects on larval mortality and average larval mass were examined using repeated measures ANOVA and between treatment comparisons were performed using Fishers LSD test (α=0.05).

Results and DiscussionAcelepryn initially provided excellent control of black cutworm (BCW) larvae regardless of application rate with BCW mortality reaching 92-95% at 3 days after treatment (DAT). The higher rate of Acelepryn provided acceptable levels of control up to 10 DAT with BCW mortality reaching 70%. However, neither rate of Acelepryn provided acceptable levels of control thereafter. Meridian 25WG failed to have any significant impact on BCW mortality even at 3 days after application. Sub-lethal effects, measured as reduced average larval mass were significant for Acelepryn regardless of application rate for up to 17 DAT with the higher rate of Acelepryn significantly reducing average larval mass for the entire duration of the study. Conversely, Merdian had no significant influence on average larval mass at any time during the experiment.

TURFGRASS SCIENCE

Residual Activity of Meridian 25WG and Two Rates of Acelepryn 1.67SC Against Second and Third Instar

Black Cutworm Larvae on Creeping Bentgrass Turf

Materials and MethodsThe The experiment was conducted at the W.H. Daniel Turfgrass Research and Diagnostic Center on the campus of Purdue University (West Lafayette, IN). The site was a stand of turfgrass consisting primarily of Pennlinks creeping bentgrass maintained at 1/8 inch. Plots measuring 0.6 x 1.2 m were arranged in a randomized complete-block design with 0.3 m alleys between plots. Treatment were applied on August 3 and each treatment was replicated 4 times using a hand-held CO2 boom sprayer configured with four 8010 nozzles operating at 30 psi and calibrated to deliver a spray volume of 2 gal/1000ft2. Three days prior to each evaluation date, one PVC cage (8” diameter) was installed on each plot and 10, 2nd – 3rd instar black cutworms were placed into each cage in order to create an artificial infestation. Field conditions on the August 3 application date were:(1) Soil Temp.: 26.7 °C (2) Air Temp: 28.9°C(3) Weather: clear, wind 0-5 mph(4) Thatch: 2.0 cm

50


These results illustrate the potential for Acelepryn to provide excellent control and some degree of extended residual activity against BCW larvae even at relatively low rates. However, results also confirm previous findings indicating that Meridian has relatively little activity against BCW larvae.

3

Table1.Mortality(%)andaveragemassof2ndand3rdinstarblackcutwormlarvaeat3,10,17,32and43daysafterapplicationoncreepingbentgrassplotstreatedwithMeridian25WGorAcelepryn1.67SC.ApplicationsweremadeonAugust3and10blackcutwormlarvaewerecagedontreatedplots3dayspriortoeachevaluationdate(Aug.6,Aug.13,Aug.20,Sept.4andSept.17).

AUGUST 6 AUGUST 13 AUGUST 20 SEPTEMBER 4 SEPTEMBER 17

Treatment Rate Product/Acre

Mort.(%)

AverageMass (g)

Mort.(%)

AverageMass (g)

Mort. (%)

AverageMass (g)

Mort.(%)

AverageMass (g)

Mort.(%)

AverageMass (g)

Untreated ‐‐‐ 10.0(±5.8a)

0.13(±0.01a)

20.0(±4.1a)

0.09(±0.01a)

12.5 (±4.8a)

0.13(±0.01a)

32.5(±7.5a)

0.16(±0.02a)

7.5(±4.8a)

0.12(±0.00a)

Meridian 25WG 17.0 oz 15.0(±8.7a)

0.10(±0.01a)

17.5(±4.8a)

0.07(±0.00a)

7.5(±2.5a)

0.12(±0.01a)

42.5(±4.8a)

0.19(±0.03a)

15.0(±2.9a)

0.14(±0.01a)

Acelepryn 1.67SC 4.0 floz 92.5(±4.8b)

0.02(±0.01b)

70.0(±10.8b)

0.04(±0.00b)

50.0 (±12.3b)

0.04(±0.00c)

42.5(±10.3a)

0.06(±0.01b)

15.0(±5.0a)

0.08(±0.00b)

Acelepryn 1.67SC 2.0 floz 95.0(±5.0b)

0.01(±0.01b)

65.0(±11.9b)

0.04(±0.00b)

7.5(±2.5a)

0.07(±0.01b)

20.0(±10.0a)

0.13(±0.02a)

12.5(±2.5a)

0.10(±0.01ab)

*Numberswithinacolumnfollowedbydifferentlettersaresignificantlydifferentatalpha=0.05

Figure 1. Installing PVC cylinders Figure 2. Flushing plot markers

Figure 3. Caged plots. Figure 4. Cutworms after flushing

51


Richmond, D., T. Gibb and A. Seiter. 2013. Influence of Ap-plication Timing on the Efficacy of Acelepryn and Merit Against Japanese Beetle Larvae in Kentucky bluegrass turf 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 52-53.

Summary: This study examined how application timing influences the efficacy of Acelepryn and Merit against larvae of the Japanese beetle.

Additional index words: White grub, chlorantraniliprole, imidacloprid, insecticide

Field conditions on the July 15 application date were: (1) Soil Temp.: 23 °C(2) Air Temp: 22 °C(3) Weather: clear, wind 0-5 mph (4) Thatch: 1.0 cmJapanese beetle larval infestations were created by driving three, 8” diameter PVC cylinders into each plot along its mid-line and caging two separate groups of 40 Japanese beetle adults (50:50 sex ratio) within each cylinder at two week intervals during late June and early July. Larval populations were assessed October 8, 2012 using a sod cutter to remove a strip of sod lying directly beneath the caging area of each plot and examining the soil to a depth of 3 inches (Fig. 1). The number of Japanese beetle larvae were counted and recorded. Variation in Japanese beetle larval populations was examined using main effects ANOVA and treatment means were compared using Fisher’s LSD test (α=0.05).

Results and DiscussionBoth materials provided excellent control of Japanese beetle larvae regardless of application timing (Table 1). Acelepryn achieved 100% control when applied during mid-July and Merit also achieved its highest level of control when applied during this time. However, no statistically significant differences in efficacy could be discerned between products or among the different application dates.

TURFGRASS SCIENCE

Influence of Application Timing on the Efficacy of Acelepryn and Merit Against Japanese Beetle

Larvae in Kentucky bluegrass turf

Materials and MethodsThe experiment was located at the Nursery Complex at Purdue University (West Lafayette, IN) on a stand of turfgrass consisting primarily of Kentucky bluegrass maintained at 7.6 cm. Plots measuring 1.5 x 1.5 meters were arranged in a randomized complete-block design with 0.3 meter alleys between plots. Each treatment was replicated 4 times. All materials were applied using a hand-held CO2 boom sprayer configured with four 8010 nozzles operating at 30 psi and calibrated to deliver a spray volume of 2 gal/1000ft2. Immediately after products were applied, plots were irrigated (approximately 1.0 cm).

Field conditions on the May 15 application date were:(1) Soil Temp.: 15.5°C(2) Air Temp: 17.0°C(3) Weather: clear, wind 0-5 mph(4) Thatch: 1.0 cmField conditions on the June 15 application date were: (1) Soil Temp.: 18.3 °C(2) Air Temp: 22.2 °C(3) Weather: clear, wind 0-5 mph (4) Thatch: 1.0 cm

52


Figure 1. October evaluation of Kentucky bluegrass plots for Japanese beetle larval population density following May, June or July applications of Acelepryn or Merit. Purdue Nursery Complex, West Lafayette, IN.

Table 1. Influence of application timing on Japanese beetle larval populations in Kentucky bluegrass turf. Populations were assessed on October 8, 2012.

Product Application Rate (oz/Acre)

Application Date Larvae/ft2

(Mean±SE)% Control

Acelepryn 1.67 SC 4.0 15-May 0.5±0.5 c 97.1Merit 75 WP 6.4 15-May 1.3±0.6 bc 92.4Acelepryn 1.67 SC 4.0 15-Jun 0.3±0.5 c 98.2Merit 75 WP 6.4 15-Jun 0.8±0.3 c 95.3Acelepryn 1.67 SC 4.0 15-Jul 0.0±0.0 c 100.0Merit 75 WP 6.4 15-Jul 0.5±0.5 c 97.1UNTREATED --- 17.0±2.1 a ---

53


Richmond, D., T. Gibb and A. Seiter. 2013. Efficacy of Single vs. Split-Application of QualiPro Imidacloprid, Aloft and Allectus Against Japanese Beetle Larvae in Kentucky Blue-grass Turf 2012. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 54-55.

Summary: This study compared the efficacy of single vs. split-applications of Imidaclorpid, Aloft and Allectus against larvae of the Japanese beetle.

Additional index words: white grub, insecticide, bifenthrin, chlothianidin

Field conditions on the August 6 application date were: (1) Soil Temp.: 22 °C(2) Air Temp: 19 °C(3) Weather: Clear, wind 0-3 mph (4) Thatch: 1.0 cm

Japanese beetle larval infestations were created by driving three, 8” diameter pvc cylinders into each plot along its mid-line and caging two separate groups of 40 Japanese beetle adults (50:50 sex ratio) within each cylinder at two week intervals during late June and early July. Larval populations were assessed October 8, 2012 using a sod cutter to remove a strip of sod lying directly beneath the caging area of each plot and examining the soil to a depth of 3 inches (Fig. 1). The number of Japanese beetle larvae were counted and recorded. Variation in Japanese beetle larval populations was examined using main effects ANOVA and treatment means were compared using Fisher’s LSD test (α=0.05).

Results and DiscussionAll materials and application approaches provided excellent control of Japanese beetle larvae with 100% control being achieved by most treatments (table 1). There was no significant difference between products and single applications performed equally as well as split-applications.

TURFGRASS SCIENCE

Efficacy of Single vs. Split-Application of QualiPro Imidacloprid, Aloft and Allectus Against Japanese

Beetle Larvae in Kentucky Bluegrass Turf 2012

Materials and MethodsThe experiment was located at the Nursery Complex at Purdue University (West Lafayette, IN) on a stand of turfgrass consisting primarily of Kentucky bluegrass maintained at 7.6 cm. Plots measuring 1.5 x 1.5 meters were arranged in a randomized complete-block design with 0.3 meter alleys between plots. Each treatment was replicated 4 times. All materials were applied using a hand-held CO2 boom sprayer configured with four 8010 nozzles operating at 30 psi and calibrated to deliver a spray volume of 2 gal/1000ft2. Plots were irrigated (approximately 1.0 cm) immediately after application.

Field conditions on the July 16 application date were: (1) Soil Temp.: 27 °C(2) Air Temp: 28 °C(3) Weather: Clear, wind 0-3 mph (4) Thatch: 1.0 cm

54


Figure 1. Japanese beetle larvae in the soil of an untreated plot during October 2012.

Table 1. Influence of single vs. split-applications of QualiPro imidacloprid, Aloft and Allectus on Japanese beetle larval populations in Kentucky bluegrass turf 2012. Populations were assessed on October 8, 2012.

Means followed by different letters are significantly different (α=0.05)

Product Application Rate(oz./Acre)

ApplicationDate

Larvae/ft2

Mean(±SE)% Control

QP Imidacloprid 2F 25 16-Jul 0.0±0.0 b 100.0Allectus GC SC 57.5 16-Jul 0.0±0.0 b 100.0Aloft GC SC 12.0 16-Jul 0.0±0.0 b 100.0QP Imidacloprid 2F 12.5 16-Jul and 6-Aug 0.0±0.0 b 100.0Allectus GC SC 29.0 16-Jul and 6-Aug 0.0±0.0 b 100.0Aloft GC SC 6.0 16-Jul and 6-Aug 0.3±0.3 b 98.5UNTREATED --- 17.0±2.1 a ---

55

Latin, R., Daniels, J., and Liu, Y. Department of Botany and Plant Pathology, Purdue University

Latin, R, J. Daniels, and Y. Lui. 2013. Integrating fungicide and genetic host resistance for control of dollar spot on creeping bentgrass. 2012. . 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 56-58.

Summary: Disease pressure is among the four major factors that influence fungicide performance (Latin, 2011). Less fungicide is normally required to achieve adequate control under conditions of low disease pressure. Host resistance to infection is an important component of disease pressure. The release of modern creeping bentgrass cultivars with measureable resistance to dollar spot infection warrants investigation into how host resistance and synthetic fungicides can be integrated for more efficient dollar spot control. Our research over two years suggest that resistant cultivars can lower disease pressure to the point where significant savings in fungicide application is quite possible, especially in fairway locations. Specifically, we found that over a four-month period, up to 83% less fungicide was used to control dollar spot on cv. Declaration (the “resistant” cultivar) than on more susceptible cultivars such as cv. Penncross and Independence.

Additional index words: Disease Management, Fungicides

although Declaration is considered a “dollar spot resistant” cultivar, it may be more appropriately termed “less susceptible” since infection will occur, but outbreaks are regularly less severe than on more susceptible cultivars such as Penncross. Figure 1 shows an image of plots of Declaration and Penncross taken after 14 weeks with no fungicide.

Figure 2 illustrates disease progress for a 7-week period on plots of Declaration and Penncross treated with Daconil Ultrex at rates equivalent to 1.8 and 3.6 oz./1000 sq. ft., respectively. In this example, three applications were made on Penncross and only 1 spray was needed on Declaration. The resulting difference was that 6 times more fungicide was required to achieve comparable levels of control on the more susceptible cultivar (Penncross) than on the more resistant cultivar (Declaration).

This research reinforces the principle that less fungicide will be required to achieve comparable levels of control under conditions of low disease pressure. Considerable savings may be realized by exploiting the host component of disease pressure. However, it depends on the availability of cultivars with strong agronomic qualities and measureable levels of host resistance. Also, because there is a

TURFGRASS SCIENCE

Integrating fungicide and genetic host resistance for control of dollar spot on

creeping bentgrass. 2012.

Materials and MethodsThe experimental site was planted and established in 2010 at the Daniel Turfgrass Research and Diagnostic Center in West Lafayette, IN. Experimental procedures were the same as reported in 2011. Fungicide applications were initiated on July 3, 2012 and were continued through the first week in October. Dollar spot severity was assessed 3 days per week by counting the number of infection centers in each plot. Treatments were applied when an average threshold of 8 spots per plot was reached.

Results and DiscussionWith no fungicide application, disease severity in plots of all three cultivars increased during the experimental period. Resistance and susceptibility to disease are opposite ends of a continuum, and

56


higher tolerance for disease outbreaks on fairways compared to putting greens, most savings will occur on the taller cut grass. From a practical perspective, the notion of regrassing fairways simply to achieve savings in fungicide expenditures is questionable. However, for new construction and renovation projects, exploiting the dollar spot resistance in more modern cultivars is a reasonable option.

referencesLatin, R. 2011. A Practical Guide to Turfgrass Fungicides. APS Press. St. Paul, MN.

Figure 1. Both Declaration (top) and Penncross (bottom) suffered dollar spot damage when left unsprayed for 14 weeks, but outbreaks were less severe in plots of Declaration.

Declaration

Penncross

57


Figure 2. Dollar spot progress curves for Penncross (red) and declaration (blue) over a 7‐week period. Using an application threshold of 8 spots per plot, Penncross was sprayed 3 times (red arrows) with Daconil Ultrex at 3.6 oz./1000 sq. ft., and Declaration was sprayed only once (blue arrow), with Daconil Ultrex at half the rate (1.8 oz./1000 sq. ft.)

Days (2012)

Infection centers p

er plot

0.0

5.0

10.0

15.0

20.0

0 10 20 30 40 50

Declaration

Penncross

58

Latin, R., Daniels, J., Liu, Y. and Hockemeyer, K. Department of Botany and Plant Pathology, Purdue University

Latin, R, J. Daniels, Y. Lui and K. Hockemeyer. 2013. Evalu-ation of Velista (penthiopyrad) for Control of Brown Patch and Dollar Spot on Creeping Bentgrass, 2012. 2012 Annu. Rep. - Purdue Univ. Turfgrass Sci. Progr. p. 59-61.

Summary: Velista is a DuPont fungicide product intended for turf markets for control of foliar diseases including anthracnose, brown patch, dollar spot, and snow molds. The active ingredient (penthiopyrad) is classified as a succinate dehydrogenase inhibitor (SDHI) that stops fungal growth by interfering with energy production in the mitochondrial electron transport system. Other turf fungicides in the SDHI class include boscalid and flutolanil, the active ingredients of Emerald and Prostar, respectively. This report documents research results from 2012, where Velista was tested for efficacy against brown patch and dollar spot on creeping bentgrass..

Additional index words: Disease Management, Fungicides

Daconil and Heritage and evaluated for brown patch and dollar spot control. Each plot in 12.5m was inoculated on June 13, 2012, by depositing 10 grains of Rhizoctonia solani-infested sorghum seed approximately 2 cm below the turf surface at three prescribed locations (designated north, middle, and south). Although the site had suffered brown patch outbreaks in the past, this method provided inoculum to a minimum of three locations within each plot. No supplemental inoculum of Sclerotinia homoeocarpa was added. In block 12.5m, treatments were applied at 14-day intervals beginning on June 8.

Block 12.5w was used to evaluate Velista tank-mixed with Daconil and Chipco 26GT and evaluated for dollar spot control only. No supplemental inoculum of S. homoeocarpa was added. In block 12.5w, treatments were applied at 14-day intervals beginning on May 23.

All fungicide applications were made using a custom-built boom sprayer. Three Tee-Jet air induction nozzles (AI9503EVS for the middle, AIUB8503EVS for both sides) were mounted approximately 12 in. apart on the boom located 14 in. from the ground. The sprayer was calibrated to deliver 2 gal per 1000 sq ft at 40 psi.

Plots in both blocks were evaluated visually for dollar spot severity at 7-14 day intervals beginning in early June. Brown patch symptoms

TURFGRASS SCIENCE

Evaluation of Velista (penthiopyrad) for Control of Brown Patch and Dollar Spot on

Creeping Bentgrass, 2012

Materials and MethodsThe research was conducted at the Purdue University Daniel Turfgrass Research and Diagnostic Center in West Lafayette, IN. The plots were located on a sward of Pennlinks creeping bentgrass maintained at a height of 0.18 in. Irrigation and aerification operations were done according to standard practices for creeping bentgrass putting greens. During spring and summer 2012, fertilizer (18-4-10) was applied at a rate of approximately 0.5 lb N per 1000 sq ft on April 12, May 16, June 15, and July 19. The entire site was treated with Daconil Ultrex (3.2 oz per 1000 sq ft) on May 7 to guard against an early outbreak of dollar spot in the plots. Individual treatment plots measured 3.3 ft by 6.6 ft (1m x 2m) and were randomized within each of the 4 replications.

The research site was organized into two adjacent blocks designated 12.5m and 12.5w. Block 12.5m was used to evaluate Velista tank-mixed with

59


did not appear until July 19. Patches appearing at inoculation points and from natural inoculum were accounted for in the visual brown patch evaluations. Data were subjected to analysis of variance and mean separation procedures. Results are summarized in the tables below.

Results and DiscussionFrom an environmental perspective, dollar spot pressure was light to moderate during the first half of the experimental period. This was largely due to drought conditions that persisted through mid July. Evening temperatures were mild, but often windy, reducing duration of the dew period. From July 20 through the end of August, environmental conditions favored dollar spot and brown patch infection.

Results from block 12.5m are presented in Tables 1 and 2. Velista treatments resulted in less disease and greater turf quality than the untreated check plots. Velista, tank-mixed with Heritage and Daconil, provided excellent brown patch control during late July and August-- a period of heavy disease. Treatments appeared less effective against dollar spot in the Velista+Heritage plots.

Results from block 12.5w are presented in Table 3. Velista treatments resulted in less disease and greater turf quality than the untreated check. I think the Velista + Chipco 26GT treatment distinguished itself from the Velista + Daconil treatment in terms of disease severity. As disease pressure increased in August, plots remained free of any dollar spot symptoms. The Velista + Chipco

# Treatment 8‐Jun 22‐Jun 6‐Jul 16‐Jul 23‐Jul 29‐Jul 13‐Aug1 No fungicide 0.70 a 1.72 a 3.55 a 5.85 a 7.35 a 10.45 a 18.41 a2 Velista 0.3 oz + 0.80 a 0.66 b 0.92 b 0.40 b 0.75 b 0.80 b 0.92 b

Daconil Ultrex 3.25 oz

3 Velista 0.3 oz + 0.75 a 0.57 b 1.54 b 0.40 b 0.32 b 0.28 b 1.11 bHeritage TL 1.0 fl oz

LSD 0.89 0.64 2.04 4.36 3.06 3.15 7.22

# Treatment 8‐Jun 22‐Jun 6‐Jul 16‐Jul 23‐Jul 29‐Jul 13‐Aug1 No fungicide 0.00 0.00 0.00 0.00 31.25 27.50 17.50 2 Velista 0.3 oz + 0.00 0.00 0.00 0.00 0.00 0.00 0.00


3 Velista 0.3 oz + 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Heritage TL 1.0 fl oz

# Treatment 8‐Jun 22‐Jun 6‐Jul 16‐Jul 23‐Jul 29‐Jul 13‐Aug1 No fungicide 0.65 a 1.17 a 2.78 a 4.26 a 4.34 a 7.26 a 11.83 a2 Velista 0.3 oz + 0.28 b 0.23 b 0.32 b 0.19 b 0.19 b 0.28 b 0.66 b


3 Velista 0.3 oz + 0.19 b 0.19 b 0.19 c 0.00 b 0.00 b 0.00 b 0.15 cChipco26GT 3.0 fl oz

LSD 0.11 0.34 0.08 1.67 1.82 3.03 0.48

Dollar spot severity (percentage of plot area with symptoms)

Brown patch severity (percentage of plot area with symptoms)

Dollar spot severity (percentage of plot area with symptoms)

Table 2. 12.5m / brown patch

Table 3. 12.5w / dollar spot

Table 1. 12.5m / dollar spot

60


26GT treatment sustained significantly less disease and had a generally superior turf quality.

Figure 1 was included to illustrate dollar spot severity in simulated filed plots where disease percentage is equal to 0.25%, 1.0%, and 4.0%.

InterpretationVelista (penthiopyrad) represents a new fungicide compound for control of foliar diseases of amenity turf. Although it occupies the same chemical class as boscalid (Emerald) and flutolanil (Prostar), the

spectrum of activity of penthiopyrad is broader than both and will be useful against a more diverse group of disease threats. Fungicide resistance has not been reported for penthiopyrad, but a medium risk should be presumed within populations of dollar spot and (possibly) anthracnose pathogens. Overuse of the fungicide is the shortest path to the development of resistant pathogen populations.

Figure1.Simulatedfieldplotswithdollarspotseverityequivalentto0.25%,1.0%,and4.0%.

0.25% 1.0% 4.0%

61

Documents

2012 Purdue University Turfgrass Research Summary Research Summary. ... (Taraxacum officinal) and wild violet (viola spp). Photo by Aaron Patton. ... selected candidate genes to specific