Cotton (Gossypium hirsutum) Injury from Simulated Quinclorac Drift

Abstract

Cotton (Gossypium hirsutum) response was evaluated when quinclorac was applied prior to cotton emergence (preemergence) and to cotton in the cotyledon and pin-head square stages in 1988, 1989, and 1990. Quinclorac applications at 9, 17, 35, 70, and 140 g ha−1prior to cotton emergence had little effect on cotton growth, with only 140 g ha−1causing stand reduction or stunting. Quinclorac application to cotton in the cotyledon stage caused more damage, and 70 g ha−1caused crop injury. Greatest phytotoxicity was observed when quinclorac was applied to cotton at pin-head square, with all rates including 9 g ha−1causing injury. Cotton injury consisted of leaf strapping and malformation of reproductive structures. Regression analysis revealed yield was reduced by quinclorac applications to cotton in the cotyledon or pin-head square stage. The approximate regression equation to predict cotton yields after pin-head square application of quinclorac was [yield] = [yield with no injury] − 10(quinclorac rate in g ha−1).

Yield and Physiological Response of Nontransgenic Cotton to Simulated Glyphosate Drift1

“…Because DD-15s are adequate for growth at all locations, we concluded that the most influential environmental factor was precipitation. Other simulated herbicide drift research on cotton has indicated significant year interactions, potentially because of varying environmental conditions Snipes et al 1991Snipes et al , 1992) that influence herbicide absorption (Wanamarta and Penner 1989).…”

“…Previous research has investigated simulated drift of glufosinate, glyphosate , quinclorac (Snipes et al 1992), and tricloypr (Snipes et al 1991) in cotton. Further studies investigating drift have indicated that drift rates typically range from 1/100 to 1/ 10 of the normally applied herbicide rate (Al-Khatib and Peterson 1999;Bailey and Kapusta 1993;Snipes et al 1991Snipes et al , 1992. Because glyphosate causes shikimic acid accumulation after absorption in sensitive plants, we hypothesized that an inverse correlation between yield and crop injury and shikimic acid accumulation would occur.…”

Response of non–glufosinate-resistant cotton to reduced rates of glufosinate

“…In evaluating the quinclorac effect on cotton at rates ranging from 0.0056 to 0.28 kg ha Ϫ1 , Crawford et al (1990) reported that 0.05 kg ha Ϫ1 applied POST at cotyledon, twoto three-leaf, or early-square stage reduced yield 13, 33, and 42%, respectively. Snipes et al (1992) observed the greatest effect of quinclorac on cotton when applied at the pinhead-square stage. Seedcotton yield losses ranged from 4.5 to 12.3 kg ha Ϫ1 for every gram per hectare of quinclorac.…”

Wheat Response to Simulated Glyphosate Drift

“…Off-target movement of herbicide during application can be somewhere between 1/10 and 1/100 of the applied rate (Wolf et al 1992) and research has addressed sublethal rates of herbicides in drift studies (Al-Khatib and Peterson 1999;Bailey and Kapusta 1993;Snipes et al 1991Snipes et al , 1992. In susceptible crops, response can be quite severe when herbicide drift occurs at sublethal rates.…”