1. Will D. Duffie 1, A. S. Culpepper 2, A. C. York 3, A. MacRae 2, P. Roberts 2 and P. H. Jost 4 1 University of Georgia, Waynesboro, GA 2 University of Georgia, Tifton, GA 3 North Carolina State University, Raleigh, NC 4 University of Georgia, Statesboro, GA 1-11-06 4:30 pm Grand Ballroom C Assessing Roundup Flex Cotton Tolerance to Over-the-top Applications of Glyphosate, Dual Magnum, Staple, PGR’s and Insecticides

2. Background Transgenic Technology (RR Flex Cotton) Weed Resistance Residual Herbicides (POT) Seed Treatments

3. planting harvest 4 leafLayby60% open bolls Roundup Ready ® Flex Cotton In-season; emergence to 60% open 4.5 lb a.e. total in-crop Max of 1.13 lb a.e. per application  Maximum of 4.5 lb ae/A from emergence to 60% open, or 128 oz W.Max or O.Max  Maximum of 1.13 lb a.e. per application, or 32 oz W.Max or O.Max  Maximum of 1.5 lb a.e. (44 oz W.Max or O.Max) from layby to 60% open  No restrictions on timing of sequential applications  Maximum of 1.5 lb a.e. (44 oz W.Max or O.Max) from 60% open till 7 days preharvest 1.5 lb a.e. 7 days Preharvest

4. Herbicide Resistant Palmer Amaranth in Georgia ALS Glyphosate ALS or glyphosate

5. Glyphosate-resistant Palmer control by residual POST cotton herbicides. 31 DAT. GA, 2006. ab d bc a c

6. Seed Treatments Thrips Control Seed treatments typically supply thrips control for 3 weeks. Temik normally provides 3+ weeks, and is rate dependent.

7. These factors warrant studying cotton plant response to post-over-top (POT) herbicide applications mixed with insecticides or plant growth regulators.

8. Materials & Methods LocationYearPlantingSeed RateApplication Dates CultivarDate(seed/30 cm)1 to 3-lf7 to 9-lf Midville, GA2005ST 4554 B2RFMay 113May 25June 16 2006ST 4554 B2RFMay 53June 6June 22 Tifton, GA2005475 WRFMay 33May 20June 4 2006ST 6565 B2RFApril 273May 24June 9 Rocky Mount, NC2005ST Flex UndesignatedMay 123June 7June 27 2006ST 4357 B2RFMay 23.5May 31June 19 Table 1. Field trial location, planting, and application information.

9. Treatment List glyphosate* glyphosate + Dual Magnum glyphosate + Staple None Orthene Bidrin Dimethoate Mustang Max Pentia (GA Only) * Roundup WeatherMax

10. Ratings taken: 1)% visual injury (after each application) Rated from 0-100 2-5 DAT 2)Yield Materials & Methods

11. Cotton injury, no insecticide tank-mix partner Herbicide treatmentCotton injury (1 to 3-lf application) Tifton, GARocky Mount, NCMidville, GA 200520062005200620052006 ------------------------------ % ------------------------------ 1) Glyphosate000078 2) Glyphosate + Dual Magnum148821535 3) Glyphosate + Staple1117811722 Herbicide treatmentCotton injury (7 to 9-lf application) Tifton, GARocky Mount, NCMidville, GA 200520062005200620052006 ------------------------------ % ------------------------------ 1) Glyphosate000000 2) Glyphosate + Dual Magnum13101160 3) Glyphosate + Staple231016037

12. No Injury

13. Leaf Burn

14. Chlorosis

15. Percent cotton injury following 1- to 3-leaf applications. Tifton, GA 2005. 3DAT. * * * * *denotes significantly different from the herbicide treatment without the insecticide.

16. Percent cotton injury following 1- to 3-leaf applications. Tifton, GA 2006. 3DAT. * * * * * *denotes significantly different from the herbicide treatment without the insecticide. *

17. Percent cotton injury following 1- to 3-leaf applications. Midville, GA 2005. 3DAT. * *denotes significantly different from the herbicide treatment without the insecticide.

18. Percent cotton injury following 1- to 3-leaf applications. Midville, GA 2006. 3DAT. *denotes significantly different from the herbicide treatment without the insecticide.

19. Percent cotton injury following 1- to 3-leaf applications. Rocky Mount, NC 2005. 3DAT. * *denotes significantly different from the herbicide treatment without the insecticide.

20. Percent cotton injury following 1- to 3-leaf applications. Rocky Mount, NC 2006. 3DAT. *denotes significantly different from the herbicide treatment without the insecticide. *

21. Percent cotton injury following 7- to 9-leaf applications. Tifton, GA 2005. 3DAT. * * * * *denotes significantly different from the herbicide treatment without the insecticide.

22. Percent cotton injury following 7- to 9-leaf applications. Tifton, GA 2005. 3DAT. *denotes significantly different from the herbicide treatment without the insecticide. *

23. Percent cotton injury following 7- to 9-leaf applications. Midville, GA 2005. 3DAT. *denotes significantly different from the herbicide treatment without the insecticide. *

24. Results Dual Magnum & Staple increased plant injury when tank-mixed with glyphosate. Orthene & Pentia slightly increased injury EC formulated insecticides (Dimethoate, Bidrin) tended to cause the highest levels of injury No yield differences observed.

25. Conclusion With the exception of Orthene, adding insecticides with glyphosate plus Dual or Staple mixtures will likely increase visual cotton injury. Environment will affect injury Injury transient, no lasting adverse effect Glyphosate/Dual or Staple/insecticide mixtures acceptable Glyphosate/Dual or Staple/Pentia mixtures acceptable