Stem Borer Research Objectives - Texas A&M University Borer Research Objectives 2 Stem Borer Insecticide Screening Experiments at Ganado The results (see table below) of both experiments

Stem Borer Research Objectives

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Stem Borer Insecticide Screening Experiments at Ganado The results (see table below) of both experiments show that two applications of Prolex at

1-2 inch panicle and late boot/heading effectively controlled stem borers (primarily Mexican rice borer). Also, Karate Z applied before flood had no effect on stem borer damage. One application of Orthene 75S (acephate) at 1-2 inch panicle or late boot/early heading reduced stem borer damage about 50%. These data will provide justification for a stem borer label for Prolex.

Insecticide screening for stem borer control in rice. Ganado, TX. 2005

Treatment

Rate lb (AI)/acre

Timing

No. whiteheadsa

Yieldb

(lb/acre) Experiment No. 1 Prolex 0.015 1 - 2" Pc 10 bc 8221 ab Prolex 0.015 LB/Hd 7 cd 8192 ab Prolex + Prolex 0.015 + 0.015 1 - 2" P + LB/H 2 d 8605 a Prolex 0.015 PDe 20 a 7678 c Intrepid 0.063 PD 19 a 7873 bc Prolex + Intrepid 0.015 + 0.063 PD + PD 17 a 7998 bc Prolex + Intrepid 0.015 + 0.063 PD + LB/H 5 cd 8492 a Untreated C C 17 ab 7649 c Experiment No. 2 Orthene 75S 0.5 PD 47 bc 4569 bc Orthene 75S 0.5 1 - 2" P 50 b 4160 cd Prolex 0.015 1 - 2" P 37 c 4484 c Prolex 0.015 LB/H 20 d 4035 cde Prolex + Prolex 0.015 + 0.015 1 - 2" P + LB/H 5 e 5495 a Intrepid 0.063 PD 46 bc 4693 bc Intrepid + Prolex 0.063 + 0.015 PD + LB/H 9 de 5274 ab Intrepid 0.063 1 - 2" P 49 bc 4542 bc Karate Z 0.03 BFf 79 a 3277 e Untreated C C 81 a 3676 de

a Number of whiteheads in 4 middle rows per plot b Yield adjusted to 12% moisture c P = panicle d LB/H = late boot/early heading e PD = panicle differentiation f BF = immediately before flood Means in a column followed by the same letter are not statistically different at the 5% level (ANOVA, LSD).


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Trapping for Mexican Rice Borer in the Texas Rice Belt in 2005

Mexican rice borer (MRB), pheromone traps were set up in most counties of the Texas Rice Belt (TRB). Data presented in the table below are incomplete; however, we detected MRB in Jefferson County for the first time. So, as of November 2005, we have detected MRB in all counties of the TRB except Orange. Because this exotic species continues to move east, the Louisiana sugarcane and rice industries are threatened.

Monthly totals of MRB adults from pheromone traps in the Texas Rice Belt in 2005 County

Month Brazoria Chambers Colorado Jefferson Liberty Matagorda

May 455 NA 174 0 NA 260

June 718 NA 236 0 22 601

July 420 NA 236 0 44 151

August 554 397 82 0 222 1219

September 1322 287 330 0 177 1436

October 3757 1583 1145 2 603 1008

November 846 1576 367 0 499 NA

December NA NA 16 NA 19 NA

NA = traps not monitored during these months

Developing Economic Injury Levels for Stem Borers The EP in cooperation with Brent Batchelor, County Extension Agent (CEA) Matagorda County, and Chris Schneider, CEA Jackson County, began studies in 2005 to determine the correlation between whitehead densities and yield loss in commercial fields in Matagorda and Jackson Counties where stem borer damage typically is higher than in other counties. Three fields in Matagorda County and two fields in Jackson County were selected. Before panicle differentiation, four paired treated and untreated transects (each transect 50 ft long and 6.33 ft wide) were established in each field. One transect of a pair was selected to be treated with multiple applications of Karate Z; the other transect was left untreated. Treated transects were hand-sprayed at least two times between panicle differentiation and early heading. When rice was in the boot stage, panicle counts (no. of panicles in three, 1 ft sections per transect) were taken. Before maturity, the number of whiteheads (in 20 ft of row) in each transect was recorded. At maturity, transects were hand harvested and yield recorded. Also, at this time 10 panicles were removed from each transect, transported to the lab where panicles were stripped of grains. Unfilled and filled grains were counted and weighed. To date, data still are being processed. However, stem borer activity was very light in all fields.

Rice Stink Bug Research Objectives

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Evaluating Selected Insecticides for Residual Activity Against the Rice Stink Bug This field/greenhouse study showed that Orthene 90S provided the best residual control of rice stink bug (RSB). We used these (see table below) and previous data to support a Section 18 registration for Orthene 90S for this insect pest. The project investigator gained the support of the USA Rice Federation and US Rice Producers Association, compiled the data and is in the process of completing the request. Our data compiled from many years’ research generally show that acephate (Orthene 75S or 90S) provides about 7-10 days residual control of RSB. Registration of Orthene 90S will save Texas rice farmers about $2,000,000 annually (based on the assumption that a single application of Orthene 90S will replace two applications of methyl parathion). This is a conservative estimate because many Texas rice farmers spray more than twice for RSB. Residual activity of selected insecticides for rice stink bug (RSB) control. Beaumont, TX. 2005

% Mortality 1 DATa 3 DAT 7 DAT

Treatment Rate

(AI)/acre 24 hrb 48 hr 24 hr 48 hr 24 hr 48 hr Untreated ---- 8 a 10 a 0 3 a 0 0 Orthene 90S 0.5 lb 78 c 93 c 33 38 c 3 3 Venom 20SG 60 g 38 b 55 b 16 26 bc 0 0 V-10170 50WGD 10 g 13 a 41 ab 5 8 ab NA NA Methyl parathion 0.5 lb 26 ab 49 b 8 8 ab NA NA Mustang Max 0.018 lb 13 a 53 b 3 10 ab NA NA Mustang Max 0.025 lb 29 ab 44 b 15 18 abc 0 0 Karate Z 0.03 lb 24 ab 41 ab 20 10 ab NA NA Sevin XLR Plus 1 lb 28 ab 58 b 21 24 abc 0 0 NS NS NS a DAT = days after treatment that RSB were exposed to panicles removed from plots b hr = hours of RSB exposure to treated panicles NA = Further RSB exposure to treated panicles ceased due to little or no residual activity at 3 DAT Means followed by the same or no letter are not significantly (NS) different at the 5% level (ANOVA, LSD).


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Spatial pattern and development of a visual sampling method for the rice stink bug, Oebalus pugnax (Hemiptera: Pentatomidae), in Texas. Luis Espino, M. O. Way, and J. K. Olson. Department of Entomology, Texas A & M University, College Station, TX

The rice stink bug (RSB), Oebalus pugnax (Fabricius), is a serious pest of rice in the southern US. The RSB feeds on rice grains during kernel development using its piercing-sucking stylets causing two types of damage: reduction in yield and the marketing quality of the grain.

The most common sampling method for RSB is the sweep net (SN). Sweeping is tedious and time consuming; but it is the only sampling method developed to determine RSB populations. Many rice producers in the Texas rice belt have not adopted the SN and rely on visual RSB counts obtained as they walk in rice fields. Treatment decisions based on these visual counts are not reliable because a sampling methodology and thresholds based on visual estimates have not been developed. The objectives of this research are: 1) develop a visual sampling methodology for the RSB, 2) determine the spatial pattern of the RSB in rice fields in Texas, 3) develop a sequential sampling program for the RSB.

Materials and Methods Three visual sampling methods were compared to the SN method: 1) T-Tool: The T-tool consists of two PVC sticks in the form of a T, one serves as a handle (1.25 m) and the other one attached perpendicular to the handle (0.65 m). The T-tool is used to lightly push panicles while walking 4.5 m in 20 sec in the field. Adult RSB observed on or in flight from the panicles in the area disturbed by the T-tool were counted. 2) Sweep stick (SS): The SS is a 1 m PVC stick that is swept 180 degrees in front of the operator disturbing the panicles. A total of five consecutive sweeps were performed, recording the number of RSBs observed on or in flight from the panicles for each swing. Only the RSBs observed on the last 38 cm of the PVC stick were recorded. 3) 1.5 m PVC pipe: For this visual method, a 1.5 m PVC stick is used to gently disturb the rice panicles while sweeping 180 degrees in front of the operator. The number of RSBs observed on or flying off the disturbed panicles was recorded. Commercial rice fields were selected and sampled during the 2003 and 2004 growing seasons in the Texas Rice Belt. Fields were divided into parallel transects 18 m apart, and samples were taken along some transects every 18 m, starting 9 m from the field margin. Visual samples (T-tool, SS, 1.5 m PVC pipe) were taken adjacent to SN samples and the number of adult RSBs observed were recorded. The data were analyzed using analysis of covariance and linear regression analysis. Taylor’s equation was used to determine the spatial pattern of the RSB in Texas rice fields. Taylor’s equation, s2=a*xb, where s2 is the variance, x is the mean, and a and b are known as Taylor’s coefficients, relates the variance to the mean and is used to classify an insect population as aggregated (s2>x), random (s2=x) or uniform (s2<x). Taylor’s equation was log transformed and Taylor’s coefficients were calculated for 2003 and 2004. Sequential sampling is a procedure in which samples are taken in sequence and the decision to treat, not to treat or continue sampling is based on the cumulative number of insects obtained. To develop a sequential sampling program the following equation for commercial sampling that incorporate Taylor’s coefficients was used:

n = t2 α or β * | ET - x|-2 * a * xb


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where n is the cumulative number of insects, α is the probability of concluding that the population density is above the economic threshold when it is not, β is the probability of concluding that the population density is below the economic threshold when it is not, ET is the economic threshold, x is the mean, a and b are Taylor’s coefficients, and t is the standard normal variate. The values of α and β were set at 0.1.

Results During 2003 and 2004, 17 rice fields were sampled, taking a total of 1036 SN and visual samples. Data were aggregated by date, cultivar, panicle development stage, location of sample in the field, time of day, type of planting, and operator. Regression analysis showed that all visual sampling method counts had a good correlation with SN counts. However, analysis of covariance showed that two sweeps of the SS (SS2) was the only method that would perform similarly at any panicle development stage (heading, milk, dough), time of day (morning, afternoon), with any cultivar (hybrid, semidwarf), and when performed by any operator. The relationship between the SS2 and the SN is given by the equation SS2=0.47+0.396*SN (r2=0.815, F=294.314, P < 0.000, Fig. 1). Using this equation the SN economic thresholds can be converted into SS2 economic thresholds. For the heading and milk panicle development stage the SS2 threshold is 2 adult RSB/SS2, and for the dough stage 4 adult RSB/SS2. Fig. 1. Regression line between the number of adult RSBs per two passes of the sweep stick (SS2) and the number of adult RSBs per 10 sweeps with the sweep net (SN).

Taylor’s equation was used to determine the spatial pattern of the RSB. Taylor’s equation was log transformed and Taylor’s coefficients were calculated for the SN and the SS2 for 2003 and 2004. No difference was found between years, therefore data were pooled and coefficients calculated for the SN (a=0.95, b=1.25) and the SS2 (a=1.19, b=1.07). Using Taylor’s equation

Number of adult RSB/10 SN sweeps

0 5 10 15 20 25 30 35

Nu

mb

er o

f ad

ult R

SB

/SS

2

0

2

4

6

8

10

12

14


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the variance was plotted against the mean (Fig. 2), showing that for most population densities the RSB has a an aggregated spatial pattern (s2>x).

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Mean No. RSB/sample unit

Va

ria

nc

e N

o.

RS

B/s

am

ple

un

it

Fig. 2. Variance-mean relationship for the sweep net (— —) and two passes of the sweep stick (- - -). The solid line represents s2=x. Figures 3 and 4 show sequential sampling graphs for the SN and the SS2 methods. These graphs are used in the following way: After taking a sample unit, the operator should locate the cumulative number of caught or observed adult RSBs on the Y axis and its corresponding sample unit number on the X axis. If the intersection point falls between the decision lines the operator should take another sample unit and evaluate the cumulative number of RSBs again. If the point falls in any of the stop sampling areas, sampling is terminated and a decision reached. Sequential sampling can reduce the time needed to reach a treatment decision by reducing the number of sample units needed to classify a population as above or below threshold.

Conclusions The present study showed that the sweep stick could be used as a visual sampling method for the RSB. Two passes of the sweep stick could replace 10 sweeps of the sweep net currently required to make a RSB population classification as above or below threshold. The equation relating both methods is SS2=0.47+0.396*SN. Using this equation the SN economic thresholds can be expressed as SS2 economic thresholds: 2 adult RSB/SS2 for heading and milk, and 4 adult RSB/SS2 for dough. Using Taylor’s equation the spatial pattern of the RSB in Texas rice fields was determined to be aggregated for both the SN and the SS2. Using Taylor’s coefficients, the economic thresholds, and α and β error rates of 0.1, sequential sampling graphs were generated for the SN and the SS2. These graphs could be used to reduce the number of sample units required to reach a treatment decision.


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Fig. 3. Sequential sampling plans for economic thresholds of 5 and 10 rice stink bugs/10 sweeps of the sweep net. Fig. 4. Sequential sampling plans for economic thresholds of 2 and 4 rice stink bugs/2 sweeps of the sweep stick.

Sequential Sampling Plan for the RSB - Method: Sweep Net

Sample Unit Numbersample unit = 10 sweeps

a=0.95, b=1.25, ET=5 RSB/10 sweeps

2 3 4 5 6 7 8 9 10

Cu

mu

lativ

e n

um

be

r of a

du

lt RS

B

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

Sequential Sampling Plan for the RSB - Method: Sweep Net


a=0.95, b=1.25, ET=10 RSB/10 sweeps

2 3 4 5 6 7 8 9 10

Cu

mu

lativ

e n

um

ber o

f ad

ult R

SB

0

10

20

30

40

50

60

70

80

90

100

110

120

Sequential Sampling Plan for the RSB - Method: Sweep Stick


a=1.19, b=1.07, ET= 2 RSB/2 sweeps

2 3 4 5 6 7 8 9 10

Cu

mu

lativ

e n

um

be

r of a

du

lt RS

B

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

Sequential Sampling Plan for the RSB - Method: Sweep Stick


a=1.19,b=1.107, ET=4 RSB/2 sweeps

2 3 4 5 6 7 8 9 10

Cu

mu

lativ

e n

um

ber o

f ad

ult R

SB

0

5

10

15

20

25

30

35

40

45

50

55

Stop sampling Action needed

Stop sampling Action not needed







Continue sampling

Continue sampling

Continue sampling

Continue sampling

Rice Water Weevil Research Objectives

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Effect of Etofenprox Formulation I on Rice Water Weevil Control

All MTI-500 formulations performed similarly relative to adult RWW feeding scars (see table below). All post flood applications, regardless of formulation, gave good control of RWW on both sample dates. However, the preflood application of MTI-500 1.5% performed as well as Karate Z applied preflood. Immature RWW populations in the untreated were very high on both sample dates (the economic injury level is about 15 immature RWW/5 cores). All treatments produced excellent yield responses. MTI-500 1.5% applied 2 days after flood outyielded the untreated 1500 lb/acre.

Etofenprox is the most widely used rice insecticide in Japan because it is much safer to humans and fish relative to other pyrethroids. Etofenprox would be an excellent addition to our arsenal of rice pest management tools, particularly in situations where rice farms are located close to fish or crayfish production ponds. The project investigator may request a Section 18 for very limited rice acreage adjacent to fish and crayfish ponds in Texas.

Effect of etofenprox formulations on rice water weevil (RWW) control. Beaumont, TX. 2005

0 no. immature RWW/5 cores Treatment

Rate g (AI)/ha

Timing

0 no. adult

RWW feeding

scars/plant Jun 17

Jun 28

Yielda (lb/acre)

MTI-500 1.5%

200

2 DAFb

10 a

15 b

7 b

8868 a

MTI-500 Form. 2

200

2 DAF

9 a

9 b

7 b

8504 ab

MTI-500 Form. 3

200

2 DAF

12 a

12 b

7 b

8850 a

MTI-500 Form. 4

200

2 DAF

10 a

11 b

9 b

8375 ab

MTI-500 1.5%

200

BFc

12 a

3 a

1 a

8423 ab

Karate Z

34

BF

6 a

2 a

2 a

8894 a

Untreated

C

C

22 b

92 c

37 c

7342 b

a Yield adjusted to 12% moisture b DAF = days after flood c BF = immediately before flood Means followed by the same letter are not significantly different at the 5% level (ANOVA, LSD). Yields, however, were significantly different only at the 15% level.


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Research on Insecticide-Impregnated Fertilizer for Rice Water Weevil Control

Populations of immature RWW in untreated plots were high (the economic injury level is about 15 per five cores) on both sample dates, so treatments were adequately tested (see table below). Mustang Max applied immediately before flood gave excellent control of RWW, regardless of the addition of urea; thus, urea did not interfere with the efficacy of Mustang Max. Yield response to Mustang Max impregnated on urea and applied before flood was 329 lb/acre greater than the untreated. When Mustang Max was impregnated on urea and applied 2 weeks after flood, immature RWW control was good which implies Mustang Max directly affected immature RWW. Earlier applications (close to the time of permanent flood) of pyrethroids target adult RWW before they lay eggs. Thus, application of Mustang Max 2 weeks after flood probably targeted immature RWW feeding on the roots of rice. This suggests Mustang Max impregnated on urea entered the mud profile where larvae were feeding. In hindsight, a foliar application of Mustang Max applied 2 weeks after flood should have been included in this experiment. However, data show Mustang Max treatments with urea produced lower yields than remaining treatments without urea, but these differences were not significant.

These data show that impregnating urea with pyrethroids is an effective method of controlling RWW. Implementation of this practice, could significantly reduce insecticide application costs. Research on insecticide-impregnated fertilizer for rice water weevil (RWW) control. Beaumont, TX. 2005

0 no. immature RWW/5 cores Treatment

Method

Rate

lb (AI)/acre

Timing

Jun 28

Jul 8

Yielda

(lb/acre) Untreated

C

C

C

42 c

51 c

7885 b

Mustang Max

Foliar spray

0.023

BFb

2 a

5 b

8363 a

Karate Z

Foliar spray

0.030

BF

2 a

0 a

8304 a

Prolex

Foliar spray

0.015

BF

1 a

0 a

8327 a

Mustang Max

Fertilizer impregnation

0.025

BF

2 a

2 ab

8214 ab

Mustang Max


0.025

14 DAFc

9 b

5 b

8212 ab

Karate Z


0.030

BF

2 a

5 b

8331 a

a Yield adjusted to 12% moisture b BF = immediately before flood c DAF = days after flood Means in a column followed by the same letter are not significantly different at the 5% level (ANOVA, LSD). Yield, however, is significant only at the 15% level.


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Experimental Seed Treatments for Rice Water Weevil Control Experimental seed treatments were evaluated for rice water weevil (RWW) control in 2005. Cruiser 5FS, A14006 and STP15299 all performed well (see table below). All seed treatments produced good yield responses. For instance, the Cruiser 5FS treatment yielded more than 1100 lb/acre compared to the check. These and other seed treatments we have tested are possible replacements for Icon 6.2FS.

Experimental rice seed treatments for RWW control. Beaumont, TX. 2005 0 no. immature RWW/5 cores

Treatment Rate

g (AI)/100 kg seed June 13 June 22 Yielda lb/acre

Untreated --- 126 e 17 8318 c

A14006 100 17 c 11 8721 bc

A14006 50 32 d 6 8865 b

Cruiser 5FS 80 7 b 6 9451 a

STP15299 42 13 bc 41 9026 ab

Karate Zb 34 1 a 14 8527 bc

NS a Yield adjusted to 12% moisture b Karate Z is a foliar spray @ 34 g (AI)/ha applied immediately before flood. Means in a column followed by the same or no letter are not significantly (NS) different at the 5% level (ANOVA, LSD).

Extension The project investigator in 2005 made about 30 on-site visits of problem rice fields. Questions were answered concerning RSB, RWW, stem borers, aphids, blackbirds, chinch bugs and fall armyworm. He also contributed to all issues of Rice Production Update and selected issues of Texas Rice and Rice Farming. He was the co-coordinator of the 2005 Rice Production Guidelines of which 1200 hard copies were distributed and about 10,000 downloads from the Beaumont Center and related web sites were recorded. He participated in all winter extension meetings, Eagle Lake and Beaumont Center Field Days, Research/Extension Conference, Ganado Site Visit and “Levee” Meetings during the summer. He organized the Youth Rice Education Contest and hosted numerous foreign visitors and school-age groups at the Beaumont Center. He represented the Texas rice industry as a member of the USA Rice Federation’s Environmental Affairs Subcommittee which met with USEPA in February. The meeting with USEPA focused on pesticide issues related to the environment. He and FMC Corporation also were responsible for gaining a rice registration for Mustang Max for stem borers in the South. Finally, he sent a first draft of a Section 18 request for Orthene 90S for RSB to all interested parties in TX, LA, MS and MO. The draft also was sent to Valent USA Corporation and members of the Subcommittee mentioned previously. So, this request will be submitted to Departments of Agriculture in TX, LA, MS and MO and USEPA before the end of January 2006.

Documents

Stem Borer Research Objectives - Texas A&M University Borer Research Objectives 2 Stem Borer Insecticide Screening Experiments at Ganado The results (see table below) of both experiments