National Cotton Council of America
Beltwide Cotton Conferences
January 8-11, 2008
Gaylord Opryland Resort and Convention Center
Nashville, Tennessee
The Cotton Foundation

Recorded Presentations

Delta Ballroom D (Gaylord Opryland Resort and Convention Center)
Wednesday, January 9, 2008
4:30 PM - 10:00 PM
Delta Ballroom D (Gaylord Opryland Resort and Convention Center)
Thursday, January 10, 2008
10:00 AM - 10:00 PM
Delta Ballroom D (Gaylord Opryland Resort and Convention Center)
Friday, January 11, 2008
8:00 AM - 5:00 PM

Effect of Late Season Glyphosate Applications on Cotton Yield and Seed Quality in Roundup Ready Flex cotton

Cory Mills and Craig Bednarz. Texas Tech University, PO Box 42122, Lubbock, TX 79409

Roundup Ready Flex (RRF) cotton, with enhanced glyphosate-resistance, is tolerant to topical applications of glyphosate from emergence to harvest. In 2006 multi-location studies were conducted with 6 RRF cotton varieties to determine the yield response and seed quality to late season topical applications of glyphosate. The field experiments were arranged in a split-split-plot design with location (5 locations, 3 in Arizona and 2 in Texas) as the main plot, application rate of glyphosate (2 rates of Roundup Weathermax, 1.125 and 2.25 lb ae/acre, respectively) as the subplot, and timing of application in terms of growth stages (first bloom, full bloom, first bloom+ full bloom, cracked boll, first + full bloom + cracked boll) as the subsubplot. The experimental results show that applications of glyphostae as high as 2.25 lb ae /acre and as late as the cracked boll stage did not affect cotton yield and seed quality in terms of the Cool-Warm Vigor Index Test (CWVI). These data show that RR Flex allows a wider window of application without the risk of yield or seed quality loss. This should allow producers greater flexibility in crop management without restricting glyphosate application to a narrow application window.