Cotton Stage of Growth Determines Sensitivity to 2, 4-D. (September 2016)

• Record Type: Journal Article
• Authors: Byrd, Seth A.; Collins, Guy D.; Culpepper, A. Stanley; Dodds, Darrin M.; Edmisten, Keith L.; Wright, David L.; Morgan, Gaylon D.; Baumann, Paul A.; Dotray, Peter A.; Manuchehri, Misha R.; Jones, Andrea; Grey, Timothy L.; Webster, Theodore M.; Davis, Jerry W.; Whitaker, Jared R.; Roberts, Phillip M.; Snider, John L.; Porter, Wesley M.
• Is Part Of: Weed technology. Volume 30:Number 3(2016)
• Page Start: 601
• Page End: 610
• Publication Date: 2016-09
• Subjects: 2, 4-D; cotton, Gossypium hirsutum L.; Crop maturity, -- Enlist™ technology, -- epinasty, -- boll distribution; Weeds -- Periodicals; Weeds -- Control -- Periodicals; 632.5
• DOI: 10.1614/WT-D-15-00191.1
• Languages: English
• ISSNs: 0890-037X

Abstract

Abstract : The anticipated release of Enlist TM cotton, corn, and soybean cultivars likely will increase the use of 2, 4-D, raising concerns over potential injury to susceptible cotton. An experiment was conducted at 12 locations over 2013 and 2014 to determine the impact of 2, 4-D at rates simulating drift (2 g ae ha −1 ) and tank contamination (40 g ae ha −1 ) on cotton during six different growth stages. Growth stages at application included four leaf (4-lf), nine leaf (9-lf), first bloom (FB), FB + 2 wk, FB + 4 wk, and FB + 6 wk. Locations were grouped according to percent yield loss compared to the nontreated check (NTC), with group I having the least yield loss and group III having the most. Epinasty from 2, 4-D was more pronounced with applications during vegetative growth stages. Importantly, yield loss did not correlate with visual symptomology, but more closely followed effects on boll number. The contamination rate at 9-lf, FB, or FB + 2 wk had the greatest effect across locations, reducing the number of bolls per plant when compared to the NTC, with no effect when applied at FB + 4 wk or later. A reduction of boll number was not detectable with the drift rate except in group III when applied at the FB stage. Yield was influenced by 2, 4-D rate and stage of cotton growth. Over all locations, loss in yield of greater than 20% occurred at 5 of 12 locations when the drift rate was applied between 4-lf and FB + 2 wk (highest impact at FB). For the contamination rate, yield loss was observed at all 12 locations; averaged over these locations yield loss ranged from 7 to 66% across all growth stages. Results suggest the greatest yield impact from 2, 4-D occurs between 9-lf and FB + 2 wk, and the level of impact is influenced by 2, 4-D rate, crop growth stage, and environmental conditions.