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 :30 pm Grand Ballroom C Assessing Roundup Flex Cotton Tolerance to Over-the-top Applications of Glyphosate, Dual Magnum, Staple, PGR’s and Insecticides

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

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

Herbicide Resistant Palmer Amaranth in Georgia ALS Glyphosate ALS or glyphosate

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

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

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

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

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

Ratings taken: 1)% visual injury (after each application) Rated from DAT 2)Yield Materials & Methods

Cotton injury, no insecticide tank-mix partner Herbicide treatmentCotton injury (1 to 3-lf application) Tifton, GARocky Mount, NCMidville, GA % ) Glyphosate ) Glyphosate + Dual Magnum ) Glyphosate + Staple Herbicide treatmentCotton injury (7 to 9-lf application) Tifton, GARocky Mount, NCMidville, GA % ) Glyphosate ) Glyphosate + Dual Magnum ) Glyphosate + Staple

No Injury

Leaf Burn

Chlorosis

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

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

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

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

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

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

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

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

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

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.

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