Almost Everything You Want to Know About Stink Bugs and What You Better Know about Roundup Ready Cotton

Transcription

1 Almost Everything You Want to Know About Stink Bugs and What You Better Know about Roundup Ready Cotton Steve Brown, Phillip Roberts, and Stanley Culpepper

2 Insecticide Applications per Acre Georgia Cotton, No. Insecticide Applications Boll Weevil Era --Active BWEP-- (does not include BWEP sprays) Boll Weevil Free low populations Bt Cotton Beltwide Cotton Conferences

3 Survey Methods Insect Boll Damage Survey: Georgia 2001 Ten fields per county. 5 Bollgard and 5 Non-Bt Fields had cutout Collected 100 bolls per field. Approximately 50 bolls collected from two locations. Sampled all harvestable bolls from individual plants. Examined bolls for insect damage. Worm Damage Bug Damage Insecticide application history. Target Pest(s) Counties Surveyed: Appling, Brooks, Bulloch, Burke, Colquitt, Decatur, Dooly, and Terrell

4 Survey Methods Green bolls examined internally. Bolls with at least one lock with significant rot were considered damaged. Worm Damage Bug Damage

5 Percent Bug and Larval Damaged Bolls Insect Boll Damage Survey: Georgia Percent Damaged Bolls Worms Bugs 39 Bollgard and 43 Non-Bt Fields

6 Percent Bug Damaged Bolls Insect Boll Damage Survey: Georgia 2001 Percent Damaged Bolls Complex of Bugs may feed on developing bolls. 0 Bollgard Non-Bt ** Prob t < Bollgard and 43 Non-Bt Fields

7 Mean Insecticide Applications Insect Boll Damage Survey: Georgia ** Bollgard Non-Bt Bugs Worms ** Prob t < Bollgard and 42 Non-Bt Fields

8 Stinkbug Complex Predominant species include Southern Green Stink Bug and Brown Stink Bug Other true bugs such as Tarnished Plant Bug and Leaf Footed Bugs cause similar damage There are predaceous species such as the Spine Soldier Bug

9 Southern Green Stink Bug

10 Brown Stink Bug

11 Striped Leaf Footed Bug

12 Bug Damage--What Does it Look Like? Fruit abortion Hawk-billed bolls External boll punctures Internal boll punctures, warts Internal rot

13 Misshapen or hawk-billed bolls result from poor pollination or poor seed development in one or more locks.

14 Bug feeding can result in external punctures. These sites serve as a means of pathogen entry into the developing boll. External sites do not always indicate internal entry or punctures.

15 Internal damage initially appears as warty growth (within 24 hr). Discoloration and rot proceeds to a single seed, lock, or throughout the entire boll.

16 Stink Bug Threshhold Depend on reliable scouting procedures They are shy, mobile creatures What is damage? Adjacent crop has significant impact Best approach: Boll DAMAGE Count

17 Aren t they shy!

18 Cotton / Peanut Interface

19 When should we spray?

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21 J. Greene, summary of 5 locations lb Lint per Acre ab a abc bc c Bidrin 2.0 Bidrin 0.6 Bidrin Bidrin $20.90* $48.48* $34.61* $10.89* 0 appl 0 10% 20% 30% 1bug/6 ft Unt *Net= $0.60/lb - $8.31/appl Threshold Level

22 Bug Threshold When 20% of medium sized bolls (the diameter of a quarter) display internal signs of feeding and stink bugs are observed. OR Treat when stink bugs number 1 per 6 row feet.

23 Stink Bug Control

24 Stink Bug Trial 2000 Irwin County GA - Tyler

25 Stink Bug Trial 2000 Irwin County GA - Tyler 100 Percent Damage Treated July Jul 2-Aug 9-Aug 16-Aug Untreated Karate Lint (lbs per acre) Untreated 866 Karate

26 2 row cotton plots in peanuts. Stink Bug Field Trial Lang Rigdon Farm Bugs per 18 Row Feet Untreated Decis 2 ozs Bidrin 8 ozs 4 DAT LSD (p=0.05) 4.4 Treated Sept 2 SG Adults Brown Adults Brown Nymphs Other

27 Southern Green vs. Brown Insecticide Susceptiblity Pyrethroids Bidrin methyl parathion Vydate OP s Bidrin methyl parathion Orthene Pyrethroids are weak on Brown Stink Bug

28 When does a boll reach the point that it will not suffer damage from bugs? About 25 days

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30 Top 12 Varieties and Technology in 2001 GA Crop B/RR RR B Conv DP 458 BR ST 4892 BR DP 451 BR DP 655 BR DP 5415 RR DP 5690 RR SG 521 RR DP 436 RR DP 425 RR NuCOTN 35B DP 5415 FM 989 Distribution across technology (% of total acreage) (USDA Ag Marketing Survey, August 2001)

31 Top 12 Varieties in 2001 GA Crop B/RR RR B Conv DP 458 BRR (20.6) ST 4892 BR (5.2) DP 451 BRR (4.8) DP 655 BRR (2.5) DP 5415 RR (16.5) DP 5690 RR (15.0) SG 521 RR (3.4) DP 436 RR (3.2) DP 425 RR (2.7) NuCOTN 35B (2.0) USDA Ag Marketing Survey, Aug 2001 DP 5415 (2.3) FM 989 (2.0)

32 Technology Distribution (%) of 2000 vs 2001 GA Crop (%) B/RR RR B Conv

33 Roundup Ready Cotton Issues Variety performance Mechanism of crop tolerance Weed management programs TIMING of applications

34 RR Cotton Variety Performance Glyphosate (properly applied) does not affect the yield of RR cultivars In terms of yield potential, RR cultivars are not superior Conventional, Bollgard/RR, and Bollgard varieties outperform RR varieties

35 In variety trials in high yield environments, RR varieties are rarely in the top 20 percent.

36 RR Cotton Mechanism of Crop Tolerance A genetically altered enzyme system provides tolerance to glyphosate in the production of shikimic acid (amino acids) Glyphosate is not degraded within the plant Excellent vegetative tolerance but marginal tolerance in developing flower Can sterilize pollen

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40 Roundup Ready Weed Management... there are many, many options.

41 Roundup Ready Programs Options (6) PPI / PRE OTT 1-2 LF OTT 2-4 LF PDIR 6-10 LF LAYBY Preferred Standard Dinitroaniline glyphosate or glyphosate + Staple diuron or prometryn + MSMA

42 RR Cotton Weed Management--Reasons to Include Conventional Herbicides in Program Reduce potential for early competition Improve control spectrum Reduce selection pressure for weed shifts and resistance Avoid phantom fruit loss with (mis) directed applications

43 Not Precise Enough!

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45 Timing is Everything!

46 4-Leaf Cotton

47 5-Leaf Cotton Too Late?

48 Not Precise Enough!

49 Precision is critical with directed applications of glyphosate in RR cotton!

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