micronutrientssturf.lib.msu.edu/article/2013feb8a.pdf(for example, 6.0 to 6.9). However, when turfgrasses are managed in high-sand-con-tent soils, organic soils or soils with high-

In order for a nutrient to be considered‘essential’, it must 1) be required for a turf-grass plant to complete its growth cycle; 2)perform a plant function that cannot takeplace without it; or 3) be directly involvedin photosynthesis, respiration, or the pro-duction or breakdown of organic materialswithin the plant, or necessary for a criticalchemical reaction.

Of the essential nutrients, carbon, hy-drogen and oxygen are supplied to turf-grasses by carbon dioxide and water. Themajority of carbon dioxide is taken upthrough minute pores, or stomates, on thesurface of leaves and stems. In addition to

moving nutrients from one plant part toanother, water also provides turfgrasses withhydrogen and oxygen.

Turfgrasses primarily absorb the re-maining essential nutrients from soil. Thefibrous nature of the root system and themassive number of root hairs contribute toa turfgrass plants ability to extract thesemineral nutrients from a soil solution.Due to the amount turfgrasses require, ni-trogen (N), phosphorus (P), potassium(K), calcium (Ca), magnesium (Mg) andsulfur (S) are categorized as macronutri-ents. The macronutrients are often furthersub-divided according to the amount re-

quired by turfgrasses. Nitrogen, P and Kare primary macronutrients, while Ca, Mgand S are secondary macronutrients. Re-sults of analyses of macronutrients in tis-sue are often reported as percent on adry-weight-basis. For example, bermuda-grass turf is often considered nutrient defi-cient if shoot tissue contains less than 2%N, 0.3% P, 1% K, 0.5% Ca, 0.3% Mg and0.2 % S on a dry-weight-basis.

EFFECT OF SOIL PH ONUPTAKE OF MICRONUTRIENTS

Micronutrients, also referred to as traceor minor nutrients, are usually found in dryturfgrass shoot tissue at levels less than1,000 ppm. Micronutrient applications areseldom beneficial to turfgrasses growing infertile, mineral soils with a slightly acid pH(for example, 6.0 to 6.9). However, whenturfgrasses are managed in high-sand-con-tent soils, organic soils or soils with high- orlow pH, the application of a micronutrientmay be very beneficial. The availability ofmicronutrients in soil for uptake by turf-grasses is influenced by the level of soilacidity or alkalinity. Plant availability of Fe,Mn, Cu and Zn decreases as the soil pHrises above neutral (7.0), while that of Moincreases with increasing soil pH (Figure 1).

ROLE OF MICRONUTRIENTSIN TURFGRASSES

Boron affects the formation of plant cellwalls and the transport of sugars. Chlorineinfluences photosynthesis, the division andlength of plant cells, and the opening andclosing of stomates. Copper is necessary forphotosynthesis and influences the lignincontent and strength of cell walls. Iron isinvolved in the production of chlorophyll.Several enzymes associated with the transferof energy, N fixation and the production oflignin contain Fe. Manganese is necessaryfor photosynthesis and is involved in theformation and breakdown of N-containingcompounds. Plants deficient in Mn for anextended period of time are, most often,very low in chlorophyll. Molybdenum is in-volved in the formation of proteins and theuse of N and S by turfgrasses. Molybdenumalso affects the production of pollen.Nickel, recently classified as an essential mi-cronutrient, is a component of an enzyme.

www.sportsturfonline.com

FieldScience | By Dr. Tom Samples, Dr. John Sorochan, Adam Thoms, and Brad Jakubowski

8 SportsTurf | February 2013

Nothing minor aboutmicronutrientsALTHOUGH TURFGRASSES CONTAIN ONLY TRACE AMOUNTSOF BORON B, chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn),molybdenum (Mo), nickel (Ni) and zinc (Zn), these eight micronutrients areessential for plant growth and survival. When it comes to turfgrass nutrition,essential micronutrients deserve attention and should not be overlooked.

Figure 1. Soil pH chart.

10 SportsTurf | February 2013 www.sportsturfonline.com

FieldScience

Several enzymes active in the production ofcarbohydrates and proteins contain Zn.

Many soil testing laboratories test foravailable B, Cu, Fe, Mn, Mo and Zn. Morethan one method (Mehlich II and III,DTPA) can be used to extract micronutri-ents from soil and results often vary fromone method to the next. After testing soil,very specific recommendations may bemade regarding the application of individ-ual micronutrients (Table 1). Interestingly,it is not uncommon for turfgrasses to re-spond favorably to an application of Feeven though a soil test report indicates thatthe concentration of the micronutrient is inthe High range. An analysis of plant tissueis recommended as a supplement to soiltesting. Micronutrient levels in turfgrass tis-

sue are usually reported as ppm on a dry-weight basis. For example, bermudagrassturf is often considered nutrient deficient ifshoot tissue contains less than 100 ppm Fe,30 ppm Zn, 25 ppm Mn and 10 ppm Cuon a dry-weight-basis. Information regard-ing specific micronutrient sufficiencyranges for individual turfgrass species or va-rieties is limited, however general or com-mon sufficiency ranges have been published(Table 2).

POSSIBILITY OF A MICRONUTRIENT DEFICIENCY

Some micronutrients are more apt to beat low or deficient levels than others. A de-ficiency of Fe in turfgrasses maintained outof doors is much more common than a de-

ficiency of the other micronutrients. Irondeficiencies are most likely to occur inpoorly rooted and thatchy turfs maintainedin calcium-rich soils with high P and pH (>7.5) levels, and very little organic matter.Turfgrasses irrigated with water high in bi-carbonates, P, Ca, Cu, Mn or Zn may alsobe deficient in Fe.

Although less commonly observed thana Fe deficiency, a Mn deficiency in turf-grasses is not unusual. A Mn deficiency, likethat of Fe, may occur in plants maintainedin soil with a high pH and Ca level. Ex-tended periods of dry, warm weather reduceMn availability in soil. Boron, Cu, Mo andZn deficiencies are rare. High levels of Cain soils can reduce the availability of B.Boron deficiencies are also more likely tooccur in turfgrasses growing in porous,sandy soils with a high pH and high level ofK. Since Cu can tightly bond with soil or-ganic matter, deficiencies of Cu have beenobserved in turfgrasses growing in organicsoils. Copper deficiencies have also oc-curred in turfgrasses maintained in sandyand alkaline soils, and soils with high N, P,Fe, Mn, Zn or pH levels. Molybdenum de-ficiencies are more prevalent in turfgrassesgrowing in acidic and sandy soils.

High levels of S, Cu, Fe and Mn maylimit the amount of Mo turfgrasses absorbfrom soil. Zinc deficiencies have occurredmore often in turfgrasses in shade, in alka-line or acidic soils, and during cool, wetweather. At present, no Cl or Ni deficien-cies have been documented in turfgrasses.

Once inside a turfgrass plant, some mi-cronutrients are much more mobile thanothers. Iron and Mn are immobile and Cl ismobile in turfgrass plants. Boron, Cu, Moand Zn are somewhat mobile. The locationof a deficiency symptom on a turfgrassplant is influenced by nutrient mobility.For example, due to the inability of a turf-grass plant to move the micronutrient fromolder to younger leaves, symptoms of a Feand a Mn deficiency occur first on youngleaves. Leaf tissue between veins of youngleaves of a plant deficient in Fe often turnsyellow then white. This condition is com-monly referred to as interveinal chlorosis.The youngest leaves of a plant deficient inMn usually develop small grayish-greenspots before the leaf tips and the tissue be-tween veins turn yellow. Turfs deficient in

www.stma.org

Mn often appear mottled. Young leaves of a turfgrass plant defi-cient in B may have yellow or white leaf tips and exhibit inter-veinal chlorosis long before older leaves. The margins of youngand middle-aged leaves of plants deficient in Cu often turn yellow,and leaf tips may have a bluish cast. Symptoms of a Mo deficiencyare much like that of an N deficiency. The older leaves of plantsdeficient in Mo ‘fire’ when the micronutrient is mobilized andmoves to young leaves. Leaves of Zn deficient plants are oftenmottled and stunted, and may roll or appear ‘crinkled’. The symp-toms of Zn deficiency may be more apparent on younger leaves.

SELECTING AND APPLYING A PRODUCTA micronutrient deficiency can be corrected by either a foliar or

soil application. Micronutrient-containing fertilizer formulationsmay be in solid or liquid form (Figure 2), and a micronutrientmay be mixed with other nutrients (Figure 3, on page 13).

Whether in liquid or solid, organic or in-organic form, a fertilizer must be applieduniformly according to label directions.

Several factors deserve considerationwhen applying micronutrients in water toturfs. They include: the weather; the type,nutrient status and growth rate of turf-grass; leaf wetness; the form of the mi-cronutrient; the product application rate,frequency and interval; the spray volume;and the spray tip. The rate at which cellsof leaves divide and expand is influencedby light, temperature, moisture and fertil-ity level. The length of time between mi-cronutrient applications can be adjustedaccording to the rate of growth of the aer-

ial shoots. The recommended product application interval may de-crease with increasing plant growth rate.

Several sources of an individual micronutrient may be availablefor use in turf (Table 3, on page 12). For example, iron (ferrous)sulfate and iron chelates are common sources of iron. Iron chelatesare most often more effective as soil applications than ferrous sul-fate, which can be highly effective when applied as a foliar treat-ment. In soil, a ferrous ion (Fe+2) from iron sulfate may quicklybe converted to a ferric ion (Fe3+), which is much less availablefor plant uptake.

Chelates are produced by combining a positively (cation) or

>> Figure 2. Anexample of a liquidfertilizer formulatedwith macronutrientsand micronutrients.

Several factors deserve considerationwhen applying micronutrients in waterto turfs. They include: the weather; thetype, nutrient status and growth rate ofturfgrass; leaf wetness; the form of themicronutrient; the product applicationrate, frequency and interval; the sprayvolume; and the spray tip.


FieldScience

negatively (anion) charged micronutrient with an organic compound or chelating agent.The reaction results in a ‘protected’ micronutrient cation or anion bound in a chemicalring structure. The length of time during which a chelated micronutrient remains in plantavailable form in soil is influenced by the soil pH, the ion that is in protected form, andthe chelating agent. Citric (CIT), acetic [DTPA, diethylene triamine pentaacetic acid;EDTA, ethylene diamine tetraacetic acid; EDDHA, ethylene diamine di (o-hydroxy-phenylacetic acid); and HEDTA, hydroxyethyl ethylene diamine triacetic acid] and oxalic(OX) acids are examples of chelating agents used to produce chelated micronutrients.

When foliar feeding, no more than one-half gallon of a micronutrient-containing solu-tion is usually applied per 1,000 sq. ft. The intent of a soil-drench (one gallon of water ormore per 1,000 sq. ft.) treatment is to carry the micronutrient through thatch and intothe soil. Turfgrasses most often respond more quickly to a foliar feeding than a granular orsoil drench application. The addition of a surfactant may, or may not, be recommended.

Thorough and uniform coverage is essential when applying a micronutrient to turfin water. The diameter of spray droplets varies depending on the spraying pressure andthe spray tip installed in the nozzle body on the sprayer boom. The diameter of spraydroplets may range from very coarse (> 550 microns) to very fine (< 150 microns).

SportsTurf 13www.stma.org

Manufacturers often rate the effectiveness of each type of spray tipas good, very good, excellent or not recommended, for specific ap-plications (e.g., broadcast liquid fertilizer; contact and systemicfungicides, herbicides and insecticides; …).

Since an application may, or may not result in a visual improve-ment in foliage color or turfgrass health even though test results in-dicate that one or more micronutrients are in the low or deficientranges, it may be advantageous to treat a limited amount of turf

with a product of interest before making a broadcast applicationover the entire sports field. ■

Dr. Tom Samples is an extension specialist for turfgrass manage-ment; Dr. John Sorochan is associate professor, turfgrass science andmanagement; and Adam Thoms is research leader, all at the Universityof Tennessee in Knoxville. Brad Jakubowski is an instructor at DoaneCollege, Crete, NE.

Figure 3. An example product label identifying the micronutrient sources and application rates.


Team: a number of persons associated together in work oractivity. Being a part of a team certainly does not guaranteesuccess, but teams that continually strive to improve and worktogether (i.e. demonstrate teamwork) will most likely performat the top of their abilities. Nearly every month, SportsTurffeatures an award-winning team of sports turf managers rec-ognized as ‘Field of the Year” winners. A common theme inthese articles is the value of teamwork. I received exceptionalmentoring regarding the importance of a team and teamworkas a young faculty member at Mississippi State Universityfrom Dr. Jeff Krans. Since those formative years in my profes-sional career, I have made it a point to emphasize to my col-leagues how much I value being a part of a team. Somethingthat gives the members of the turfgrass program at VirginiaTech great satisfaction is how our clientele refer to us as theVT Turf Team. And nowhere have I said being part of a teamis easy—securing the information for this article and getting acover photo of the team was akin to herding cats!

The VT Turf Team’s collabora-tion across departments, pro-grams, and colleges in ourteaching, research, and extensionprograms has been cited by manyadministrators as a model forother programs at Virginia Tech toemulate. Our VT Turf Team isalso much more than just the fac-ulty, staff, and graduate studentsin our traditional academic pro-grams, but it also includes ourstaffs that manage all VT athleticand recreational sports fields. Ourathletics turf and recreationalsports programs support turfgrassresearch, participate in our re-search field days, and are con-

stantly “on call” for field andfacility tours, something veryimportant to our fund-raising andstudent recruiting activities. Wealso proudly claim as team mem-bers a large number of allied ex-tension agents, private individuals,industry, and professional associa-tion cooperators around the statethat assist us with financial sup-port, on-site research opportuni-ties, and the hosting of a variety ofoutreach programs.

I want you to meet a few of myVT team membersand I asked themto join me in providing a brief high-light of some of our sports turf-re-lated research projects. Thesereports are but very small parts oftheir research programs, and if youhave further questions of my col-leagues regarding this or other proj-ects they are leading, please be sureto get in touch with them by way ofthe contact information available atwww.vt.edu.

BERMUDAGRASS EXPANSION ON VIRGINIA SPORTSFIELDS-Mike Goatley. Virginia’stransition zone climate makes itpossible to grow either cool-seasonor warm-season grasses on athleticfields, but none of them very well.Either type of grass is going to regu-larly struggle from an extreme sum-mer or winter season. A part of myapplied research program is varietyevaluation and my turfgrass pro-gram manager, Whitnee Askew, andI have spent a great deal of time as-sessing bermudagrasses that we be-lieve are well suited for athletic field

Inside look at the turfteam at Virginia Tech

>> FIGURE 1. A dormant but extremelydense Riviera bermudagrass field inearly December 2012 at Wilson Me-morial HS, Waynesboro, VA (photocourtesy of Jimmy Rodgers).

The data continually indicate what great potential the latest generations ofcold tolerant vegetative and seeded bermudagrasses have for sports fields.

FieldScience | By Dr. Mike Goatley, STMA President

INSTEAD OF A TRADITIONAL ARTICLE* on the STMA President forthis month’s issue, I asked for the opportunity this year to tell you a little bitabout the turfgrass program at Virginia Tech and some of the great work mycolleagues are doing that might apply to you.


use in our climate. The data continually in-dicate what great potential the latest genera-tions of cold tolerant vegetative and seededbermudagrasses have for sports fields.

Depending on your perspective (see Dr.Askew’s research brief below), bermudagrassis either an outstanding sports turf grass ORit is one of the world’s worst weeds. Forsports turf, bermudagrass offers transitionzone sports field managers the opportunityto take advantage of the exceptional densityand aggressive growth rate of this grass. Inparticular, these grasses have now made theirway onto athletic fields throughout the Val-ley and Ridge region of Virginia at elevationsof 2,300 feet or higher. As for any naturalgrass field, they still must be used and man-aged appropriately to meet expectations, butwith proper traffic management, these fieldsare providing exceptional playing surfaceseven as dormant turfs.

The one point of caution I bring to anyfacility considering a conversion is the inten-sive mowing requirement of bermudagrass inthe summer. However, if this maintenance

requirement is properly addressed, the endresult is usually a more uniform playing sur-face and fields that require much less irriga-tion and pesticide use than comparativecool-season fields.

The most recent success story in Vir-ginia’s Shenandoah Valley is Wilson Memo-rial HS where football coach (and VSTMAmember) Jeremiah Major seeded Rivierabermudagrass the summer of 2012. Jere-miah and his team delivered an exceptionalfield by the season opener in August, buteven more impressive was the quality of histurf well into the playoffs in late November(Figure 1). The performance and conditionof these fields certainly captures the atten-tion of opposing coaches, players, and par-ents and has led to many fact-findinginquiries about a grass that they previouslyconsidered only to be a serious weed.

BERMUDAGRASS/WIREGRASSCONTROL–Shawn Askew. Dr. Askewhas statewide responsibilities for developingweed management systems in turfgrass. He

conducts weed control, herbicide physiol-ogy, and weed ecology experiments in alltypes of turf including athletic fields. Hisgraduate students are currently working onseveral projects that may impact weed man-agement in athletic fields.

In Virginia’s climate, bermudagrass isboth a desirable turf and a weed. Dr.Askew and his graduate students haveworked hard over the past 8 years to de-velop selective bermudagrass control pro-grams for cool-season turf, especially forKentucky bluegrass athletic fields.Fenoxaprop + triclopyr programs were de-veloped years ago in North and South Car-olina and work great for tall fescue turf. Inlower height turf and Kentucky bluegrass,the ester formulation of triclopyr can beextremely injurious to Kentucky bluegrassturf and fenoxaprop is much more injuri-ous to immature turf of any species whencompared to mature turf. Both of thesephenomena can be problematic for athleticfield management where Kentucky blue-grass and lower mowing heights are com-

mon and immature turf will always bepresent due to the need to manage wearareas.

Dr. Askew’s research suggests thatfenoxaprop + triclopyr should only be usedin early spring or late fall where immatureturf is less prevalent and should be re-placed with mesotrione or mesotrione +triclopyr at low rates during stressful peri-ods of summer. Applications of eithermesotrione or fenoxaprop mixed with tri-clopyr can effectively control bermuda-grass in cool-season grasses. Just rememberto reduce triclopyr rates in hot weatherand on Kentucky bluegrass, switch fromfenoxaprop to mesotrione both to savemoney and reduce potential damage to thebluegrass during stressful summer weather,and concentrate on fall treatments to getthe best kill (repeat treatments at a 3-4week interval).

Two new herbicides that are currentlyunder investigation by Dr. Askew’s groupinclude topramezone and metamifop. Bothherbicides show great promise for selectivebermudagrass control and topramezonecould be registered within the next year(Figure 2). Both herbicides work betterwhen mixed with triclopyr but offer supe-rior turf safety and bermudagrass control toother herbicides currently on the market.No herbicide, however, will controlbermudagrass alone but must be mixedwith other herbicides and applied 4-6 timesper year in a program approach tobermudagrass eradication.

TURF TOLERANCE TO RIGID TURFPROTECTION SYSTEMS–Erik Ervin.Dr. Erik Ervin is a Professor of TurfgrassPhysiology in the Crop and Soil Environ-mental Sciences department of VirginiaTech and has primary responsibilities inteaching and advising in the undergraduateprogram. This research brief summarizeswork supported by VT Athletics and theU.S. National Park Service and was com-pleted in 2012 by M.S. student John Royse.

The presidential inauguration, the na-tional book festival, the solar decathlon,and a U2 or Dave Matthews Band concert:what do these events have in common?They are all multi-day set-up and take-down events (often involving cranes) thattake place on natural turfgrass surfaces (e.g.,

the National Mall and MLB fields) withthousands of attendees. Many times the ac-tivities are so intense that major turf deathoccurs and complete re-grassing is required.Managing or softening the conditions thatcause major turf loss, however, is preferred.Unfortunately, there have been almost noscientific studies investigating the positivesand negatives of current practices.

In 2010 and 2011 we conducted multi-season event cover simulation trials to de-termine how long a mature tall fescue turf(2.5 inch mowing height on a silt loam soil)could survive and what some of the control-ling factors might be (e.g., light, compres-sion resistance, soil moisture, temperature).Two commercially available rigid high-den-sity polypropylene covers were compared toplywood-alone or plywood over Enkamat(Table 1). Terratile is a single-sided, white,translucent cover with foot pads and airholes used primarily for seating or foot-traf-fic protection, while Matrax LD is a dou-ble-sided, white, translucent cover with noair holes used primarily for vehicle-trafficprotection. Each spring, summer, or fallseason covers remained on the turf for 2, 4,6, 8, 10, 12, 14, 16, 18, or 20 days givingus a look at turf persistence and recoveryevery 2 days during a 3-week period (Figure3). Using linear regression we were able toestimate how long tall fescue could be cov-ered (and driven over daily with a truck)and not have more than 40% turf loss(Table 1).

We found that light availability played amajor role in turf persistence and recovery.The translucent Terratile and Matrax prod-


FieldScience

Table 1. Light transmission, average maximum high temperature under cover, and thepredicted days until 40% or greater tall fescue loss following covering of various turfprotection systems in summer or fall/spring.

High temperatureunder cover

Number of days under cover be-fore >40% turf loss, tall fescue

Cover name

Terratile

Matrax LD

Plywood over

Enkamat

Plywood

Light transmission

25%

5%

0%

0%

Mean across 2summer seasons (oF

108

100

101

104

Summer1

10

12

1

1

Fall/Spring1

>20

>20

5

5

1Average high air temperatures during the two summer test periods was 94oF, while thatover the four spring and fall test periods was 70 oF.

>> FIGURE 2. White tissue symptoms that normally occur from the topramezone treatments (centerplot is topramezone alone) are reduced or nearly eliminated and bermudagrass control increasesdramatically when topramezone is tank-mixed with triclopyr (plots on left or right) (photo courtesyof Shawn Askew).

ucts allowed 5 to 25% of photosyntheticallyactive radiation through to the leaf bladeswhen measured at solar noon. During coolerspring and fall periods this resulted in almostcomplete turf persistence and recovery evenwhen covered for the entire 20-day test pe-riod, while both plywood treatments allowedfor only 5 days of cover. During summer,extra light transmission through Terratile re-sulted in significantly higher temperatures re-ducing turf persistence to 10 days comparedto 12 days for Matrax. Plywood or plywoodover Enkamat resulted in almost completeturf death after only 2-4 days of cover in thesummer. Our results were clear and consis-tent: Use of a rigid cover that allows somephotosynthetically active light to reach theturf canopy is of primary importance, withair exchange and compression resistancebeing important, but secondary.

SPRING DEAD SPOT SDS MANAGEMENT IN BERMUDAGRASS –David McCall. David is a research associ-ate and PhD candidate in the Plant Pathol-ogy, Physiology, and Weed ScienceDepartment of Virginia Tech. He has pri-mary responsibilities in turfgrass pathology.

In Virginia, where a growing number ofathletic facilities have transitioned to im-proved varieties of bermudagrass, the mostfrequent disease-related question I hear is“What can I do about my Spring DeadSpot?” As most who have managedbermudagrass know, spring dead spot(SDS) is the most common and damagingdisease of bermudagrass (Figure 4.). Notonly is the disease highly unsightly, but a se-

vere patch can be depressed to bare ground,often half an inch or more below the surviv-ing turf stand. This can play havoc onplayability and increase the chance for ath-lete injury.

For decades, a standard recommendationfor suppressing SDS has been to use ammo-nium sulfate as a primary nitrogen sourcethroughout the summertime. This wasbased on research on one of the pathogens,Ophiosphaeralla herpotrica, which is mostcommonly found throughout the GreatPlains and other Midwestern states. Thegeneral belief was that all species of thecausal agent (there is also O. korrae, mostcommon in Southeastern US, and O. na-mari, most common in Australia and NewZealand) would respond the same to nitro-gen sources. However, research from the

turfgrass pathology program at North Car-olina State clearly demonstrated that O. her-potrica and O. korrae responded differentlywhen clean bermudagrass was inoculated.O. herpotrica responded as expected, andwas suppressed with ammonium sulfate. O.korrae, on the other hand, did not respondto this, but did to calcium nitrate. Whilethe impact on disease activity is not fullyunderstood for each species, we do knowthat sulfur-based nitrogen sources will lowerpH in the upper rhizosphere, and most ni-trate sources have little effect on pH.

Because of the widespread problem forturf managers in Virginia, field research trialswere initially established on sites with severeSDS epidemics in the spring of 2010 to seehow quickly this new guideline may reducedisease. Trials were established on one soccerfield (Southwestern Virginia), two golfcourse fairways (Central Virginia and theEastern Shore), and one research plot at theHampton Roads AREC in Virginia Beach.Plots with pre-existing SDS were fertilizedwith ammonium sulfate (21-0-0), calciumnitrate (15.5-0-0), or soluble urea (46-0-0).Two additional management strategies wereapplied to test confounding effects of nitro-gen source. Plots were split to test whetherfall applications of fungicides can speed therecovery of SDS. Interaction with late sum-mer vertical mowing was also examined.

While the NC State research showed dra-matic results for new patch development, in-corporating various nitrogen sources intopre-existing conditions in our trials has not


FieldScience

Table 2. White grub counts in 2011 Turfgrass Soil Insecticide Efficacy Trials, Tazewell Co., VA.

Treatment/Formulation/ Application rate White grubs per sq ftApplication Timing1 (amt product/acre) (± SEM)2 Untreated check — 24.13 (3.48) a

DPX-HGW86 20 SC April 8.0 fl oz 23.25 (5.22) a

Merit 75 WP April 6.4 oz 22.00 (4.26) a

Zylam 20SG July 32.0 oz 19.00 (3.42) ab

Allectus GCSC April 4.5 pints 9.00 (1.63) b

Acelepryn 1.67 SC July 8.0 fl oz 2.00 (1.08) c

DPX-HGW86 20SC July 8.0 fl oz 0.75 (0.48) c

Acelepryn 1.67 SC April 8.0 fl oz 0.00 (0.00) c

Merit 75 WP 6.4 oz 0.00 (0.00) c1Early application: 20 April; late application: 19 July

2Means within a column followed by the same letter are not significantly differentat P < 0.05 according to LSD tests.

>> FIGURE 3. Differential tall fescue response after covering for 6 days in the fall with Matrax/Terra-trak (top) or Plywood+Enkamat (bottom) (photo courtesy of John Royse).>> FIGURE 4. Spring Dead Spot on a Riviera bermudagrass athletic field in Rocky Mount, VA(photo courtesy of David McCall).


reduced disease as rapidly. To date, resultsfrom site to site have been highly inconsis-tent, but no fertility regimen in combinationwith other management strategies has provento be a silver bullet. What appears to be ef-fective in one plot may have little to no re-sponse in the next. This inconsistency led tous to wonder whether each site had mixedpopulations of the SDS pathogen. If bothspecies of Ophiosphaerella are present at onesite, then no one nitrogen source would sup-press the disease. One of the treatments in-cluded both ammonium sulfate and calciumnitrate, but this still has not adequately sup-pressed disease. While the current researchwill continue for at least 1 more year, we areshifting our primary focus to understandingthe population dynamics across the state andwithin a given field. In collaboration withthe Plant Disease Clinic at Virginia Tech, weare working to develop a rapid identificationtest that will allow turf managers to knowwhat is causing the majority of their SDSproblems. While SDS suppression strategiesare still evolving, we are growing increasinglyconfident that our work will improve sportsturf managers’ ability to make well informedand site-specific management decisions.

WHITE GRUB CONTROL - Rod Young-man. Dr. Youngman is an extension ento-mologist with statewide responsibilities inintegrated pest management in turfgrass,field corn, and forage crops.

White grubs have been the major focus ofmy applied research and extension outreachprograms in Virginia. These root-feeding lar-vae feed on all of Virginia’s sports turf grassesfrom mid-spring until killing frost, but theycause the most damage on cool-season ath-letic fields during the heat of summer. Dam-age from a heavy infestation of grubs is oftenmade worse by the burrowing of foraging an-imals and birds such as skunks, raccoons,and crows. The damage can literally makefields unfit for play due to the surface dam-age and the subsequent poor footing of dam-aged turf (Figure 5).

The results of this research (Table 2 indi-cate several important findings regardingchemical grub control. The mid-April appli-cations of the experimental DPX and Merit75 WP (imidacloprid) treatments did notperform well, but at the late application(same rates) they ranged among the top per-

formers. DPX-HGW86 is being positionedas a rescue treatment by its company. Al-though the traditional grubicide Merit nolonger has the staying power (April-Augustwhite grub control) it once enjoyed, the per-formance of its July application is directly inline with the white grub life cycle. Whitegrub egg-laying typically begins mid-Julyand peaks the first-second week of August inour area. Acelepryn (chlorantraniliprole) pro-vided excellent grub control in either early orlate season applications; the season-long grubcontrol from its April application and its ad-ditional control prospects for turf caterpillarsmakes this a very promising insecticide formany turf uses.

In addition to continuing work in thisarea, we have also started evaluating ento-mopathogenic fungi and nematodes as bio-logical control agents against annual whitegrubs. If successful, these combinationsmight greatly expand our options in biolog-ical grub control.

DALLISGRASS CONTROL INBERMUDAGRASS - Jeffrey Derr andAdam Nichols, Hampton Roads Ag. Res.and Ext. Center. Dallisgrass Paspalum di-latatum is a warm-season perennial thatspreads by short rhizomes as well as by seed.Dallisgrass clumps expand over time due torhizome growth. Its wide blades and tallseed heads make the weed especially appar-ent in bermudagrass turf. Dallisgrass is atroublesome perennial grass in a number ofturf situations, including sports turf. It in-vades both warm and cool-season turfgrass,

where there are limited control options.MSMA, the most commonly used herbicidefor dallisgrass control, currently can only beused in golf courses, sod production, andrights of way areas. It is unclear what turflabels will exist for MSMA in the future.Additional control options are needed forthis weed in turf.

We have been investigating herbicides,herbicide combinations, and herbicide ap-plication timing for dallisgrass control inbermudagrass. The herbicides tested includeRevolver, Celsius, Tribute Total, and Monu-ment. We have included MSMA for com-parison. All of these herbicides will injuredallisgrass, although this weed will recoverfrom single applications. Label restrictionsprevent making more than two applicationsper season for some of these products. Wehave rotated herbicides in our repeat appli-cations to stay within label restrictions. Wehave tested multiple spring, multiple fall,and spring followed by fall applications. We

compared broadcast applications to spottreatment. For certain herbicides, a higherdose can be applied using a spot treatment,although only about one quarter of the totalturf area could be treated using these doses.

Two applications of Celsius plus Re-volver in spring provided 45% dallisgrasscontrol in summer, but the dallisgrass com-

>> FIGURE 5. Damage to a Kentucky blue-grass/perennial ryegrass athletic field fromskunks foraging for white grubs.

>> FIGURE 6. Dallisgrass is very noticeable inbermudagrass due to its wider blades and tallseed heads.

Continued on page 45


FieldScience | By Dr. Eileen Buss

ISAT IN ON AN INTERESTING DISCUSSION at the National Entomologi-cal Society of America meeting in Reno,NV in late 2011. There were talks on theuses, advantages and disadvantages of si-

multaneous pesticide combinations in inte-grated pest management strategies. Here aresome of the highlights:

First of all, the terminology is confusing andcertain words mean different things to differentpeople. Let me define a few terms according tothe Insecticide Resistance Action Committee(IRAC) before I go too far.

Pesticide combinations: applications of twoor more compounds to the same pests at thesame time. Specific examples are tank mixes andpremixes.

Tank mix: a mixture of two or more prod-ucts (they don’t just have to be insecticides) on-site or on a mix/load pad by an applicator. Eachproduct is often applied at a high labeled rate.Sometimes a “tank mix” may be thought of asmixing one product with water in a tank, butthat is not how I’m using the term in this article.

Premix: a commercial product containingtwo or more active ingredients. At least one ac-tive ingredient is usually applied at a lower ratethan if used alone. This “premix” category isdifferent from the use of something like water-soluble packaging of a single insecticide.

Why would anyone use a combination ofproducts, rather than just applying one productat a time? There can be pros and cons, eitherway. The most common reason to combine pes-ticides is to kill more pests with one application.Many of the newer insecticides have fewer targetpests (are “narrow-spectrum”) and may have dif-ferent routes of entry (contact vs. plant sys-temic), so if you apply two or more at one time,then you have a more “broad-spectrum” treat-ment. Other benefits may include reducingtransportation costs (if you kill most pests ini-tially, there may be fewer call-backs), like savingon fuel, reducing the amount of packaging, de-creasing possible turf injury from repeated trafficor soil compaction and decreasing the spread ofdisease or pests on equipment. Client satisfac-tion (at least in agriculture) tends to be higherwhen mixtures are used, and mixtures may beless expensive than do-it-yourself tank mixes.

Another reason to use a mixture or pesticidecombination is to slow down the developmentof resistance in some pests. However, this is notthe typical motivation of applicators, and I

would appeal to you to weigh the pros and consof this when choosing your pesticide inventory.I was amazed that in agriculture, a lot of insecti-cide mixtures have been used over the last 50+years—e.g., abamectin (Avid) plus thi-amethoxam (Meridian) on pears against psyllidsand aphids. The list was so long, I couldn’twrite down all of the combinations.

Mixing products is not as easy as it sounds.With any kind of mixture, there are some thingsto watch out for. It is possible to get “antago-nism” between compounds, which means thatthe mixture is less effective than when the singleproducts are used alone. There is also the risk ofplant damage or “phytotoxicity,” which is morelikely to occur when mixtures are applied tostressed plants (e.g., drought-stress), but separateapplications of the compounds would not hurt aplant. And, “physical incompatibility” canhappen if two compounds or formulations reactto each other or physically can’t combine (anissue of compatible solubility). The result couldbe a big glob of goo in your spray tank.

Some cautions to be aware of: Avoid mixinginsecticides that have the same “mode of action”or are in the same chemical class. From a resist-ance management perspective, if an insect is re-sistant to one insecticide (e.g., bifenthrin), thenwhat good would it do to add anotherpyrethroid (e.g., permethrin, deltamethrin,lambda-cyhalothrin, etc.) to the mix? Therecould be cross-resistance within the same chemi-cal class or even across other classes, so youwould only be exerting the same selection pres-sure to the pest. For example, carbamates andorganophosphates act essentially the same wayon an insect, and pyrethroids and DDT simil-iarly have some cross-resistance. Hopefully, youremember that a mode of action is how an insec-ticide acts (e.g., interferes with the sodium chan-nel) at its target site (e.g., the nervous system)within the insect.

Another caution is to avoid using the samemode of action (single product or mixture)against the same generation or life stage of thetarget pest. This may be easier said than done inthe southeastern US, especially Florida and theCaribbean, where we have overlapping lifestages of pests nearly year-round. Ideally, onetreatment could be used to knock out most ofone pest generation, then if needed, you couldcome back to treat the next generation or when-ever damage reoccurs.

Similarly, if a treatment of some product

doesn’t work the first time, don’t keep applyingit again in the hopes that attempt #2 or #3might be more worthwhile. Doing the samething over and over again when you know itdoesn’t work is insanity (and arguably unethicalif you’re getting paid for the job). Be aware thattreating with a brand name product and at thesame time with a generic product at the highestlabeled rates equals a 2X application, which isillegal. Again, the goal is to reduce selectionpressure and use products wisely, not nukeeverything. Modes of action can be determinedby finding the “Group” number on a productlabel or by looking up the active ingredients onthe IRAC website (http://www.irac-online.org).

The last caution I heard at the meeting wasthat premixes should not be used unless allcomponents within the product are needed.

ADVANTAGES, DISADVANTAGES OF MIXES

The advantages and disadvantages of tankmixes and premixes were thoroughly discussedat this meeting. For example, commercial pre-mixes have the advantages of being convenientto use, the active ingredient rates are un-changeable, the component rates and formula-tions are optimized during development, nomixing or stability issues should exist, and atleast one component is usually applied at alower-than-labeled rate. Some disadvantagesinclude the inability of an applicator to changethe active ingredients, all target pests should bepresent at the same time, and premixes mayhave been designed for specific pests or regionsof the US but could be used outside of the op-timal treatment zone. From an economicstandpoint, premixes may be created by manu-facturers as part of a post-patent marketingplan to obtain a licensing extension.

Some advantages of tank mixtures includegiving the applicator some flexibility to providetreatments that fit the pest control need at thattime, and they help to reduce any excess pesti-cide inventory that might exist. However, theflip side is that creating a tank mixture is lessconvenient, it’s potentially hazardous to peoplewho are not trained to properly mix products,“homemade” tank mixes may not be as stable asa premix, and the products being combinedtend to be mixed at the highest labeled rates.

According to IRAC there are some require-ments for a mixture to be considered effective.First, all toxins should persist the same length of

Clarifying and magnifying concepts in the pesticide industry


time where the mixture is applied. Completecoverage of the treated plant is essential. Thereshould be no cross-resistance between the tox-ins. In effect, both compounds should each beable to kill the target pest, which is called “re-dundant killing.” As turfgrass managers, we arenot chemists, and we don’t know if only one ofthe compounds in the mix is doing all the heavylifting or if there is really a benefit to havingboth compounds in the mix.

Whether or not mixtures are useful in pes-ticide resistance management is controversialamong applicators, researchers and regulators.Some say that the use of mixtures in resistancemanagement is not supported by either com-puter models or field experiments, althoughlab tests can make mixtures appear to work. Itis possible that a mixture could incompletelykill multiple life stages of a pest, instead ofkilling everything it was intended to kill. Thatmeans that some bugs still survive, lay eggsand pass on their resistance genes to the nextgeneration.

I asked someone at that meeting if theythought it might be possible to restore the useof a product when resistance levels were really

high (like bifenthrin and chinch bugs in partsof Florida), and they pessimistically said that itwas too late. I hope that’s not true. They alsosaid that resistance management should startbefore field failures occur. So the time isNOW to determine how to delay resistancedevelopment in the neonicotinoids like Arena(clothianidin), Meridian (thiamethoxam) andMerit (imidacloprid).

RESISTANCE MANAGEMENT STRATEGY

Okay, so I also had the question of what aresistance management strategy should looklike. Should each pest generation only be ex-posed to one active ingredient? Should all of aspecies’ populations be treated with the samecompound at the same time, or should each in-fested site be treated differently? In lawn care,that is what we do—each lawn is treated differ-ently often by different companies, thereby cre-ating a “mosaic” effect, unless a wholeneighborhood is under the management of onepest management company. If property 1 istreated with bifenthrin (Talstar) and neighbor-ing property 2 is treated with clothianidin

(Arena), then what happens next? Any survivinginsects on either property may find each other,mate and have offspring that can better survivean application of either compound appliedalone or mixed together. Almost sounds like acliff-hanger; we can’t predict how fast resistancewill develop to another compound in this com-mon type of scenario.

So, what does this all mean? Be good prod-uct stewards and help us develop a functionalresistance management plan for turf. Imple-ment integrated pest management or IPM.Avoid treating turfgrass unless you absolutelyhave to, which admittedly challenging for aroute-based business. Just because you treatgreen grass and it stays green after an applica-tion does not mean that a product worked—itmay mean that no pests were present and caus-ing damage at the time of application. Overuseof products like this is one route to developingproduct failures down the road. ■

Dr. Eileen Buss is an associate professor, Ento-mology & Nematology Dept., University ofFlorida. This article first appeared in the FloridaTurf Digest’s July/August 2012 issue.


FieldScience

Editor’s note: We asked some top-of-their-game STMA members aboutstrategies they employ to help their fields recover from winter more quickly.Here are the questions:

1. What’s your experience with fertility strategies coming out of winter?2. What’s your experience in controlling any winter diseases you’ve seen?3. What topdressing materials do you use? Why those particular materials?4. If you overseed, what’s your advice on removing the overseeded grasses?

GRANT SPEAR, CSFMAthletic Fields SupervisorUniversity of Nevada, Las Vegas

Winter in Las Vegas typically means dormant bermudagrass fieldsfor 3-4 months. If a field is not overseeded, the bermudagrass will startto slowly grow in March. Fertilizing with a 3/4 to 1 pound N per thou-sand square feet and 4% Fe in late March or early April following top-dressing with sand or better yet, sand with 20 to 30% peat helps tospeed things along (the darker the topdressing, the better). Of courselonger days and 80+ degree highs and 60+ lows help much more. I haveyet to see any disease issues other than physical damage from excessiveuse of a dormant field when it’s wet in the winter.

Overseeded fields behave and are treated differently here. Typically,ryegrass remains green but grows very little for us after mid-Novemberuntil the end of January. Topdressing with a dark sand helps a little butmost fertilizer seems to have very little effect until the days get longer inearly February. Late January, I start fertilizing overseeded turf at about3/4 pound of N per thousand square feet with about 4% Fe every 3-4weeks until about a month before I want to transition the turf back tobermudagrass.

The bermudagrass base turf is much slower coming back when com-peting with perennial ryegrass, but by late May it’s usually coming back.Depending on field use in May through the end of June we spur thebermudagrass along by controlling the water to stress the ryegrass andlowering the mowing height from 1" to 3/4" or from 5/8" to 5/16" oninfield turf. Heavier applications of urea (1-1.5 lbs N per thousandsquare feet) add to the stress on the rye and speed the encroachingbermudagrass.

If more complete, quick removal of the rye is optimal and adequatetime is available for the bermudagrass to grow, transitioning herbicideslike Monument and Revolver are the way to go. One week after treat-ment, I start to hit it with fertilizer again.

JEFF HAAGSports Turf SpecialistJohn Carroll University, University Heights, OH

Currently I try to avoid making any fertilization application in thisregion until late April so that I don't deplete the carbohydrate reserves Ihave built up heading into winter for our cool-season grass. If therewould be a need to apply any I would try to limit it strictly to recoveryareas and not as a blanket application for an entire field.

I do apply a dormant fertilization application to continue to storecarbohydrates for the following spring and summer the last week of No-vember. Last year it was applied on November 26.

In this part of the country (outside Cleveland) the main concern ispink snow mold; however, here at John Carroll we do not apply anyfungicides to any of the athletic fields. But when I was the golf coursesuperintendent/sports turf manager at Bowling Green State University,I applied a tank mixture of iprodione (Chipco 26GT) and Daconil(chlorothalonil) as a preventive for pink snow mold with great success.

I topdress using a coarse USGA spec sand because the coarser gradeallows for better drainage.

Since we have cool-season grasses here at John Carroll we do nothave to overseed. When I was at the University of Louisville we over-seeded the bermuda fields with perennial rye, and found that the prod-uct Katana removed the rye the quickest and with minimal turfdiscoloration.

CHRIS “BUTTER” BALLSports Turf ManagerGwinnett Braves (GA)

Typically we load up ourbermuda with potassium for thewinter. We usually apply 1-1.5lbs of N all winter, typicallydone with one granular app, sup-

plemented by foliars. In the Southeast it has been rare the last few yearsthat the bermuda has gone totally dormant, in my opinion, which reallyhelps as the weather starts to turn. We start the spring by lowering themowing heights on our ryegrass, and applying small but frequentamounts of N as soon as the air temp breaks 65-70 and our bermudastarts to show signs of life.

Most of the winter diseases we see in the Southeast are on our rye-grass. Preventative apps of broad spectrum fungicides made starting inlate January and early February, usually do the trick. We also are on aphosphate program that has been a large piece of our puzzle the pastfew years. I also believe it is a must that getting your potassium built upin late summer and all fall is a vital to a healthy transition.

We typically use a sand for topdressing that is very similar to ourrootzone base. We are 100% sand and have found a source that matchesour rootzone very, very closely. We also topdress with green sand in thinand wear areas as needed. Kiln-dried green sand is a must in our pro-gram.

We do overseed, (unfortunately) due to some of the February andMarch games we play. My philosophy the past 10 years or so has beento go out late and very light with our ryegrass seed. Last year (2011) wewere close to 5lbs/M and this year (2102) we are at 4-4.5lbs/M.

We do not take the rye out chemically for transition. We start to dropthe mowing heights as soon as possible (late March-early April) typicallyfrom 5/8” to 1/2”. When our team is on the road for an extended periodof time we will often take our turf down to 3/8”. We will apply a poly-coated N-P-K granular and really start to pour our foliar program to ourturf by spraying small amounts of N every 7-10 days. We also use greenpigments as much as possible to draw heat into the plant and start to aer-ify with small solid tines as much as possible early during transition, whilelarge core aerification is done in June, July, August, and September. Fre-quent light topdressings also help us push our transition.

Getting faster turf recovery coming out of winter


TODD TRIBBLEAthletic Field SuperintendentOklahoma State University

Like most athletic fields inthe transition zone we are forcedto overseed our bermuda stand

with perennial ryegrass. We have to stay fairly lean on our nitrogen in-puts on our baseball field in mid-September and October when theoverseed is somewhat weak and hasn’t yet begun to tiller and mature.During this time we supplement once a week with a light foliar applica-tion until November. As soon as fall practice is over the first of Novem-ber we push out a starter application of 18-24-12 at 0.75lbsN/1000.

Our other go-to product when the soil temps begin to drop to theupper 50’s at a 4” level has always been an IBDU product at 1.5lbsN/1000. This is a can’t-miss product for us here. It is perfect for coolseason grasses such as rye as it is slowly soluble and the release is basedon moisture availability, not temperature or the activity of microorgan-isms. Usually we will come back 8 weeks later at 1lbN/1000 of thesame product to get us through the end of February when our soiltemps are warm enough to use more conventional fertilizer methodssuch as ammonium sulfate.

If I see a 4 or 5 day window of warmish weather for Stillwater dur-ing January or February (mid-upper 60’s) we will usually go out at light

rates (.25-.33lbsN/1000) of a soluble product to give our rye a quickkick of growth and allow for some recovery from the daily practices andgames. Unfortunately, after this winter draws to an end we will beforced to find a different slow release source that mimics IBDU as it ismore or less unavailable to us now. Beyond the end of February, we usea 13-2-13 at 0.75lb rates to help with repair and color maintenanceuntil early June when the season comes to an end. We know that withfairly low nitrogen rates for that 7-month time frame our team is play-ing on rye we can keep growth where we need it[DASH HERE]not toolush but still be able mow each day and remove some tissue.

We have been fairly fortunate here in Stillwater to not have greatwinter disease pressure. We do get snowfall each year but in all yearsbut one it has burned off within 4 days or so. In the winter of 2010 wedid get 9” of snow and in our right field corner at baseball snow driftspiled up 3+ feet of snow. It took about 2 weeks of good temperaturesfor this to burn off and we did see some light instances of snow mold.Consequently, I will only spray preventatively for snow mold if we havea storm coming that will blanket us fairly heavily with snow and the10-day forecast does not allow for melting. In such cases I will use achemical with a combination of the active ingredients chlorothalonil,propicanozole and fludioxonil before the storm arrives.

The practice of topdressing is important for many reasons, includ-ing quicker recovery from turf injury/damage, enhanced overseed,thatch decomposition, and smoothing out our playing surfaces. We arealways sure that the material we use is of a similar or slightly coarserparticle size than our overall rootzone. If you really want to take a sci-

entific approach to it, test the percolation rates of your field as is, thentest your proposed sand. If the sand from the supplier drains at a fasterpace than what your current perc rates are, that might be a good optionfor a topdressing material; just make sure it isn’t too course so that itcan’t be worked into the turf canopy with a mat.

A particle size that is finer than what was used at the time the fieldswere built can lock up pore space, decreasing air, water and gas move-ment, impacting the availability of nutrients due to roots hitting a“physical barrier” in the rootzone, and create compaction issues overtime. Obviously for us, it is important to find a USGA spec type sandthat fits our needs and is not much more expensive per ton than a local,“dirtier” type of masonry sand. We recently built a new 4-acre footballcomplex and are lucky enough to get our sand from the same plant asthe one who provided the rootzone mix at time of initial construction.

Certainly we overseed in Stillwater with our being in the transitionzone. Each year we use perennial ryegrass to keep our softball, soccer,and baseball fields green for the late fall/winter/spring months. As soonas the season ends for each sport we immediately (day after) eliminatethe stand of rye chemically with the active ingredient foramsulfuron.We are fortunate in the fact that our coaches understand our urgent ap-proach to ryegrass removal. Our camp schedules in the summer areusually played on a weaker stand of bermuda as it recovers from thesmothering of the overseed. Like most turf scientists have included intheir presentations, the importance of having as close to a 100-day timeframe of having a healthy stand of pure bermuda cannot be overstated.

For our baseball field specifically this can be a difficult thing to ac-complish with the season extending into June. The past two seasons wehave regularly maintained our rye at 0.75” but dropped to 0.625”when the team is out of town. This imparts some stress on the rye forthat time period and we hope that our permanent stand of bermudacan jump in and slowly overtake the rye in May. During this same timewe begin to up our nitrogen inputs to further encourage the bermudato take off. These two practices certainly do not lead to a 100% standof bermuda and probably never will but it does allow us to cheat a littlebefore June 5 spray out time. Rye that isn’t removed simply hangs on allsummer in clumps and alters the uniformity of the bermuda.

AMY J. FOUTY, CSFMAthletic Turf ManagerMichigan State University

The fall and winter in Michigan can be very different from year toyear. Over the years I have changed my fertility strategies to best matchthe changing environment. I have gone away from late fall applicationsof fertilizer and typically wait to fertilize in the spring time until thesoil temperatures averages 50 degrees. Fifty degree soil temperatures sig-nify that the ground will most likely not freeze again and that the turf-grass plant is beginning to actively grow. We often get periods of rainsand warm spells during the winter months that unthaw the ground; bywaiting I feel that we do not waste our fertilizer or money. As far as thetype of fertilizer we use in that first application I like a quick tomedium release to quickly green up the turf and start the rejuvenationprocess for the plant.

We use a combination of cultural practices and chemical applica-tions to control winter diseases. We typically do not push the bluegrasswith a lot of N in the fall. I believe that the plant can better store carbo-hydrates using this fertility method and prepare the plant naturally to de-fend against the winter if I am not pushing shoot growth. Second, we tryto solid deep tine aerate the fields that we need to get out on the earliestin the spring so that the soil and plants have the healthiest environmentpossible through the winter months.

Diseased areas are often low light areas or compacted soils that do notdrain well, so we try to alleviate these issues as best we can by openingthem up in the late fall. Finally, at the end of our fall season we typicallymake preventative snow mold application. I like to wrap these applica-tions up the last week of November.

The type of topdressing materials that we use is based on the exist-ing soil structure in each of our facilities. For example, we have an engi-neered sand system in Spartan Stadium that we have matched sod andsoil to, and then in 2010 engineered topdressing material for as well. It isall based on the distribution of the particle size of our soil test to main-tain positive drainage and air movement through the soil structure.

Finding the proper balance of fines, medium, and course particles iscritical for stability and drainage. Basically it equates to 95% well gradedsand and 5% silt and clay in the stadium. On our other fields I also con-sider how aeration will mix the existing soil and topdressing material asnot to upset the rule of thumb; coarse materials over fine equal positivedrainage.

In our northern climate we typically overseed year round with Ken-tucky bluegrass seed mixes on the fields just before events, camps, andrentals for the athletes to work in the seed. We have had great successover the years just sticking with the Kentucky bluegrass. The only fieldsthat receive any rye/Kentucky bluegrass blends of seed are our practicefields in the fall. The winter weather typically desiccates the rye for us sothere is no need to chemically remove it. We start again in the springwith straight Kentucky bluegrass.

JOHN WATT, CSFMAthletic Field ManagerNorth Kansas CitySchools

My best results of turf qualitycoming out of the winter comefrom applying a pound of nitro-gen that is quick release in the

late fall. Then in late winter months, end of February, we apply ½ poundof nitrogen to kick start the bluegrass. Three weeks later, when soil tem-peratures warm up, apply the ½ pound of nitrogen to continue growthand recovery from spring sports. At the K-12 level, spring sports season isvery short, so we need to start as early as possible to get the grass growingfor quick recovery.

My budget doesn’t allow for a preventative fungicide program, so I tryto stick to cultural practices going into the winter months. My crew andI use growth blankets as much as possible. We focus in areas that can beprone to winter disease or where there is a low threshold for thin turf


FieldScience

On our other fields I also consider how aeration will mix theexisting soil and topdressing material as not to upset the rule of thumb;

coarse materials over fine equal positive drainage.


when spring season starts up, for example soccer goal mouths.I usually use a 90/10 sand:peat mixture. I choose this for ease of ap-

plication and addition of organic material into the native soil.We don’t overseed.

VINCE HENDERSON, Park Services ManagerJASON MELTON, Sports Turf ManagerHenrico (VA) County Parks & Rec

We are 100% warm season turf and since we are in the transitionzone we try to be patient with our nitrogen fertility on overseeded andnon overseeded fields. We overseed mostly for color on our baseballfields and for early season tournaments on soccer fields. We start fertil-izing these fields when we begin mowing and typically use a water solu-ble fertilizer such as ammonium sulphate or urea with a ureaseinhibitor at .25 -.50/ lb per 1000 rate. We are even more patient withnon overseeded fields due to the possibility of a late freeze. Very mildwinters usually lead to early green-up of these fields, but a late heavyfrost or freeze can really hurt these fields if they are too lush. We reallytake a wait and see approach to these fields. Sometimes we may get intoApril and need to push them a little, but more often we try to waituntil the grass wants to grow.

The only major problem we have with disease has been spring deadspot on our baseball stadium field. We have had mostly good results inusing fenarimol (Rubigan) at split 4 oz/1000 rates. The best timing forthe applications has been late August or early September and then again4 weeks later. Going forward, Rubigan will not be available, so we willhave to use an alternative fungicide if we decide to continue with fungi-cide applications.

Another way we have tried to combat this problem is the use of nitro-gen sources. Calcium nitrate seems to help, but we cannot be sure if it isthe fertilizer source or the fungicide applications or a combination ofboth that has helped. We have tried to use information from Dave Mc-Call at Virginia Tech and research done by Dr. Lane Tredway at NorthCarolina State to combat this problem.

Over the years we have mostly used sand to topdress our fields, butwe have moved more to using compost on all of our fields except oursand-based stadium field. The sand-based field is topdressed with amatching sand when we core aerate. We do not use compost on this fieldso that we keep from creating a layer that will inhibit drainage.

On our native soil fields we try to incorporate .25” of compost withsome type of cultivation process, whether it is core or solid time aeration.We have seen a great response with using compost in early spring to pro-mote growth and enhance color and believe that over a period of time wewill create a better soil structure. We have also found that topdressingcompost in conjunction with sprigging has really helped our grow-inprocess.

We started using compost due to a recommendation by Dr. AndyMcNitt at Penn State when we renovated a native soil field to improvesoil structure and drainage. This particular renovation required 2” ofcompost be tilled into the top 8” of soil. The results were excellent, so wehave since incorporated this into our cultural practices.

It is important to note that we have found an excellent source forcompost that is clean of sticks and debris and is easy to spread and alsofree of weed seeds due to their composting process. The cost of composthas also been cheaper than sand. The truth is that with the number offields we maintain (81 irrigated fields) we don’t have enough time to top-dress as much as we would like.

This question really depends on the type of weather we have. Ourperfect scenario would be to scalp the rye and turn off our irrigation sys-tems for a week or so and let Mother Nature take care of the rest. Thisalso works well with some type of cultivation process such as slicing. If itis a cooler-than-normal spring and the ryegrass is thriving and thebermuda is lagging a little we may wait a short time, but then use achemical application to reduce the competition between the two grasses.

Another factor to consider is if we will need to sprig or repair wornareas of a field that has been overseeded. In this case, we must be carefulto plan the chemical application accordingly in case a window of time isneeded. We have typically used trifloxysulfuron-sodium (Monument),because we are also able to control sedges and some broadleaf weeds ifneeded. We try to use as few chemical applications as possible.

SHANE YOUNG, CSFMGrounds SupervisorPrince William County (VA) Park Authority

I don't fertilize warm or cold season turf until my pre-emergent appin early April.

Since being in my current position for past 12 years, I have only seenspring dead spot on bermuda. It usually it grows right out of it.

I don't topdress my bermuda soccer fields anymore because the re-ward wasn't worth the cost.

I overseed my bermuda and let it transition out naturally. I use transi-tional rye though. ■


FieldScience | By Joey Fitzgerald

HOW CAN EARTHWORMSBE BENEFICIAL TO US ASTURF MANAGERS? Weknow of the natural aerification

that takes place from earthworm activity inthe soil, ultimately opening up pore spacefor root growth and improving water andoxygen movement, but is there any otherway that we can benefit from these slimycreatures? It turns out that through aprocess called vermicomposting we can po-tentially reap countless advantages in mak-

ing turfgrass more stress tolerant while im-proving soil structure while reducing de-pendence on chemical and pesticide use.

Vermicomposting is an organic processused to convert agricultural and other wasteinto valuable living soil amendments. Theend result of the vermicomposting process isthe production of earthworm excrement, re-ferred to as castings. These castings arepacked with beneficial nematodes, protozoa,fungi, organic matter, plant growth regula-tors (humates and fulvates), plant growth

hormones (IAA and gibberellins), and solu-ble nutrients (N, P, K, Ca, and Mg).

SOIL NEEDS ORGANICMATTER AND MICROBES

To fully understand the benefits ofworm castings, it is best to first compre-hend the need for sufficient organic matterand healthy microbial activity in the soil.Organic matter serves as a storehouse fornutrients in the soil. Unlike soluble syn-thetic fertilizers, the nutrients stored in or-ganic matter and microbial bodies do noteasily leach out. The organic matter formsaggregates with fungus and other beneficialbacteria making it difficult for nutrientleaching from heavy water movementthrough the soil profile.

The diverse addition of microbial life tothe plant’s leaf surface and rootzone hasmany benefits, but perhaps the greatestand most direct benefit comes as a popula-tion addition to the soil food web. Thisaddition helps to maximize a continualcycle of breaking down and releasing nu-trients into plant-available forms accessibleto the roots. As bacteria and fungi feed onorganic matter in the soil, they store nutri-ents within their body while releasing oth-ers. Then as nematodes and protozoa inturn prey on them, nutrients are releasedfrom the bacterial and fungal bodies intothe soil in a plant available-form ready for

Organic matter serves as a storehouse for nutrients in the soil.

Use earthworm castingstea for better turf

>> THE BEGINNING of the brewing process—thestraining bag of worm castings is placed in water.

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root uptake. When organic matter is fed tothe soil, the microbial life then feeds nutri-ents to the plant.

BENEFITS OF WORM CASTINGSNutrient Cycling and Retention: As

mentioned earlier, aggregates formed frommicroorganisms within the soil greatly re-duce nutrient loss, ultimately reducinggroundwater contamination. Less nutrientleaching, coupled with a healthy microbialpopulation unlocking nutrients already inthe soil, leads to a lessened need for thequantity of fertilizer output.

Microbial Diversity: The addition of anincredibly diverse population of microor-ganisms from the worm castings helps max-imize the productivity of the soil food web.

Water Retention: As the amount of or-ganic matter within the soil increases, so toodoes the water holding capacity of that soil.

Disease Suppression: Spraying wormcastings tea populates the soil and leaf sur-face with an exorbitant amount of microbesall searching for a food source to survive.

This diversity ensures that all of the organ-isms have a predator in the soil; because ofthis, no one organism can easily reach pop-ulations high enough to cause damage ofany significance. Working symbioticallywith the plant’s roots system in this wayhelps to eliminate harmful molds and fungifrom inoculating the plant’s surface.

Worm castings don’t do miracles againstall plant disease; however, research com-

pleted by Dr. Norman Arancon and Dr.Clive Edwards at Ohio State has shownthat worm castings suppress Pythium ulti-mum and Rhizoctonia solani diseases. Fur-ther research conducted by the PlantSciences Department at Cornell Universityshows that the beneficial microbes colonizeseed surfaces masking the chemical signal-ing needed for the pathogen to locate thehost material.

>> LEFT: The middle of the brewing process. The foam indicates good microbial activity in the tea. >> RIGHT: This is the finished solution with a tea bag in the foreground.

Insect Control: Worm castings are richin chitinase, a chemical that decomposesthe exoskeleton of insects. Many researchersbelieve that its presence in the castingsprove inhibitory to many damage-causinginsects.

Plant Available Nutrients: Worm cast-ings provide soluble nutrients to the plant.The nutritional analysis can vary dependingon the food source during the vermicom-posting process, but generally the castingshave around 1-3% N, .5-1% P, and 1-2%K. These levels are low, but they are imme-diately ready for plant uptake.

APPLICATION PROCESSWorm castings can be applied a couple

of different ways. Like any compost, thecastings can be spread in a finely ground,dry formulation. Dry application would bemore useful in a situation when it could be

added directly to the soil profile during arenovation or construction.

When applied to the plant, the best andmost cost effective application method is bymaking a tea from the castings. Much likemaking a pot of tea at home, the concept ofthis tea is to simply use water to extract allof the “good stuff ” from the worm castingsinto a liquid solution that can easily be ap-plied. This process can be done two differ-ent ways: extracted or aerobically brewed.Aerobically brewed teas require more timeto produce, but the end product is a solu-tion with exponentially higher microbialpopulations than that of extracted teas.

This aerobic tea brewing process is fairlysimple, but it does require some time, at-tention, and know how. A variety of brew-ing containers and methods are availableand can be used; however, a key point tokeep in mind when producing the castingstea is that because the tea is a living solu-tion, oxygen and a food source must becontinually available to the microorganismsin the tea for survival and maximum popu-lation growth.

During the STMA Conference last yearin Long Beach, CA I sat in on an educa-tional program presented by Leif Dickinsonabout his practices with growth regulatorson his bermudagrass at Del Mar Thorough-bred Club. During the presentation hementioned his use of worm castings tea

brewed with alfalfa to jump start his turfout of large patch symptoms in the springtime. Our field had experienced large patchthe previous fall, so this concept caught myattention. I began looking for any addi-tional information or research anywhereabout the benefits or drawbacks from theusage of worm castings tea on turfgrass.What I found was a wealth of success storiesfrom gardeners, crop producers, and thegreenhouse production industry, but noth-ing more documenting real success on turf-grass. After reading all of the different usesand benefits, I came to the realization thatonce you strip everything down, growingquality turfgrass isn’t really that much dif-ferent from growing other crops, so I de-cided to give brewing an aerobic castingstea a try.

For the brewing system I retrofitted anair bubbling system off of a 10-gallon aircompressor we had sitting around. Webegan spraying in mid-March as ourbermudagrass had begun coming out ofdormancy. My intention was to make threeapplications on 2-week intervals with mylast application coming in mid-April; in-stead I got hooked on the results we werehaving and continued spraying on the bi-monthly interval schedule for the remainderof the growing season.

OBSERVATIONS FROM TRIALAND ERROR APPROACH

• Because our field displayed the visualsymptoms of large patch in the fall, I natu-rally anticipated those same areas to appearas the field broke dormancy in the spring.When the turf woke up from the winter,the infected areas from the previous fallwhere nowhere to be found.

• I was amazed how well the “usual sus-pect” wear areas handled traffic throughoutthe year. Even before the bermudagrass sea-son really kicks into gear, the turf dealt withour 18 high school game, pre-Lookouts sea-son slate with ease. From my observation,this improved wear tolerance continuedthroughout the 2012 season.

• Even though we had a substantiallydrier summer, two different observations Imade this year can speak to improved waterretention in our soil. First, we did not havean occurrence of fairy ring, which the fieldhad experienced the previous six seasons.


FieldScience

>> THIS IS OUR BREWING SET-UP with the air compressor in the middle of the four containers andPVC piping branching off of that.

>> CLOSE-UP view of the dry worm castings.


Our fairy ring symptoms are the result ofthe inability of water to penetrate throughthe hydrophobic tendencies of the thatchlayer, ultimately resulting in a plant thirstyfor water. Secondly, we dodged having tobabysit any dry spots resulting from our de-ficient irrigation system.

These are only the observations over thecourse of the 2012 growing season whencompared to the previous season. Are theseresults an anomaly or were they because of atweak in our cultural and fertility manage-ment? I would be naïve to think that theseresults can be only be attributed to the ad-dition of the worm castings tea, but I dobelieve when coupled with good manage-ment practices, positive results will follow.

WHERE TO GO FROM HEREThe idea of turfgrass benefiting from ver-

micompost is a relatively new concept.Much additional education and research isneeded about the functionality of the addi-tion of these microorganisms from theworm castings to the soil; however, our re-

sults over the past season indicate that thereis a place for castings tea in environmentallyfriendly turfgrass management practices.Whether it be reducing synthetic fertilizer,pesticides, groundwater contamination,water use, etc., it is becoming difficult to es-cape ever-growing environmental concernsand restrictions. Because of this, any prod-

uct or concept that can assist in limitingnegative environmental impacts while work-ing in conjunction with our daily manage-ment practices should be explored. ■

Joey Fitzgerald is the head groundskeeperfor the Chattanooga Lookouts.

>> BEFORE A GAME on August 14, 2012.


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pletely recovered by fall. Applying a singleCelsius plus Revolver treatment in springfollowed by a single Celsius plus Revolvertreatment in the fall also did not provide ac-ceptable long-term control of this weed.Two applications of Celsius plus Revolverin fall, two applications of Celsius plus Re-volver in spring followed by two applica-tions of Monument in the fall, or twospring applications of Monument in springfollowed by two applications of Celsius plusRevolver in fall are all providing 80% orgreater dallisgrass control going into winter,comparable to that seen with multiple ap-plications of MSMA. Multiple fall applica-tions of Tribute Total have injureddallisgrass, but have not provided accept-able long-term control. Injury to the

bermudagrass was noticeable but not unac-ceptable, especially at higher doses, for cer-tain of the herbicides tested, and longerlasting in the fall.

We will be following these trials in thespring to determine if dallisgrass can outgrowthe effects of these treatments. With theproducts available for dallisgrass suppressionin bermudagrass, it appears that multiplespring and fall applications will be neededfor acceptable dallisgrass control. Applica-tions may need to be timed to spring whendallisgrass greens up and resumes growth inspring, as well as treatments in the fall toweaken the plant going into winter. Adju-vant addition, including ammonium sulfateand methylated seed oil, may also be benefi-cial in these spray programs.

Those reports come from a few of myVT Turf Team colleagues. I encourage youto also get to know your state or regionalcollege and university turf teams and famil-iarize yourself with the work that they aredoing. You never know when a turf emer-gency might arise where you could use an-other set of eyes and ears to help you solve aproblem. Your support of these programsmakes you a part of the team and teamworkis always a key to success.

*Martin Kaufman, CSFM was to bethe new STMA President but when hetook a new position last year he wasforced to resign per association bylaws soDr. Goatley agreed to stay on the jobthrough 2013. ■

Continued from page 19

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Documents

micronutrientssturf.lib.msu.edu/article/2013feb8a.pdf(for example, 6.0 to 6.9). However, when turfgrasses are managed in high-sand-con-tent soils, organic soils or soils with high-