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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #199497
Title: Influence of Cotton Size on Injury from Flumioxazin and Glyphosate Applied Post-Directed

Author
item FERRELL, J - UNIVERSITY OF FL
item Faircloth, Wilson
item BRECKE, B - UNIVERSITY OF FL
item MACDONALD, G - UNIVERSITY OF FL

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2007
Publication Date: 7/1/2007
Citation: Ferrell, J.A., Faircloth, W.H., Brecke, B.J., Macdonald, G.E. 2007. Influence of Cotton Size on Injury from Flumioxazin and Glyphosate Applied Post-Directed. Weed Technology. v 21. p 709-713.

Interpretive Summary: In 2004 and 2005, glyphosate + diuron and flumioxazin + MSMA were applied to cotton at 20, 30, 40, and 50 cm in height. These herbicides were directed to either the lower 2 cm on the cotton stem or to the lower 50% of the cotton stem to determine the impact of application timing and placement on cotton response. Glyphosate + diuron resulted '22% injury when applied high on the stem and '8% injury when applied low on the stem. Regardless of application placement or timing, no yield reductions were observed as a result of glyphosate + diuron application. Conversely, flumioxazin + MSMA applications resulted in 93 and 64% injury when applied high post-directed (HPD) to 20 and 30 cm cotton, respectively. Low post-directed (LPD) applications made caused 33 to 23% injury for 20 and 30 cm cotton, respectively. In both years, HPD applications of flumioxazin + MSMA on 20 cm cotton resulted in excessive yield loss (94 - 87%), while yield loss was only noted in 30 cm cotton in 2004. No yield loss was observed in 40 or 50 cm cotton. Additionally, LPD applications of flumioxazin + MSMA, though causing significant visual injury, did not result in a yield penalty at any application timing. Although cotton became more tolerant to flumioxazin + MSMA as the season progressed, the research suggests that applications of flumioxazin should only occur when cotton reaches 40 cm in height.

Technical Abstract: In 2004 and 2005, glyphosate + diuron and flumioxazin + MSMA were applied to cotton at 20, 30, 40, and 50 cm in height. These herbicides were directed to either the lower 2 cm on the cotton stem or to the lower 50% of the cotton stem to determine the impact of application timing and placement on cotton response. Glyphosate + diuron resulted '22% injury when applied high on the stem and '8% injury when applied low on the stem. Regardless of application placement or timing, no yield reductions were observed as a result of glyphosate + diuron application. Conversely, flumioxazin + MSMA applications resulted in 93 and 64% injury when applied high post-directed (HPD) to 20 and 30 cm cotton, respectively. Low post-directed (LPD) applications made caused 33 to 23% injury for 20 and 30 cm cotton, respectively. In both years, HPD applications of flumioxazin + MSMA on 20 cm cotton resulted in excessive yield loss (94 - 87%), while yield loss was only noted in 30 cm cotton in 2004. No yield loss was observed in 40 or 50 cm cotton. Additionally, LPD applications of flumioxazin + MSMA, though causing significant visual injury, did not result in a yield penalty at any application timing. Although cotton became more tolerant to flumioxazin + MSMA as the season progressed, the research suggests that applications of flumioxazin should only occur when cotton reaches 40 cm in height.