Rice (Oryza sativa) and Corn (Zea mays) Response to Simulated Drift of Glyphosate and Glufosinate¹

Abstract

Field research was conducted during 3 yr to evaluate response of rice and corn to simulated drift rates representing 12.5, 6.3, 3.2, 1.6, and 0.8% of the usage rates of 1,120 g ai/ha glyphosate (140, 70, 35, 18, and 9 g/ha, respectively) and 420 g ai/ha glufosinate (53, 26, 13, and 4 g/ha, respectively). Early-postemergence applications were made to two- to three-leaf rice and six-leaf corn, and late-postemergence applications to rice at panicle differentiation and to corn at nine-leaf stage (1 wk before tasseling). Crop injury was generally greater for the two highest rates of both herbicides when applied early. Little to no reduction in rice or corn height was observed with glufosinate. Glyphosate consistently reduced rice plant height when the two highest rates were applied early, and heading was delayed 2 to 5 d. In 2 of 3 yr, the highest rate of glyphosate reduced rice yield 99 and 67% when applied early and 54 and 29% when applied late. Germination of rice seeds from glyphosate-treated plants was reduced in 1 of 2 yr and for only the highest rate. For glufosinate, rice yield was reduced 30% and in only one year when applied late at the highest rate. Early application of glyphosate reduced corn yield an average of 22 to 78% for the three highest rates, but only for the highest rate at the late timing (33%). Corn yield was reduced an average of 13 and 11% for the highest rate of glufosinate at the early and late timings, respectively. In greenhouse studies, five rice varieties were equally sensitive, as were five corn varieties, to reduced rates of glyphosate and glufosinate.

Glufosinate Effects on Nitrogen Nutrition, Growth, Yield, and Seed Composition in Glufosinate-Resistant and Glufosinate-Sensitive Soybean

“…However, both crops recovered rapidly and glufosinate exposure did not affect yields. In another study, glufosinate application at 53 g/ha reduced yields up to 3 to 30% in rice and 11 to 13% in corn [14].…”

“…Glufosinate rate of 45 g/ha was selected to represent 10% of the suggested label use rate (450 g/ha) to simulate herbicide drift. Other researchers have used 1 to 20% of recommended rate in herbicide simulated drift studies with various crops [13,14,16,17].…”

Environmental impact of herbicide regimes used with genetically modified herbicide-resistant maize

“…Crop yield was reduced on average of 22-78% for the three highest rates when GLY was applied early post-emergence, whilst crop yield was only reduced by 33% for the highest rate at the late timing. Maize yield was reduced on average by 13 and 11% for the highest rate of GLU at the early and late timings respectively (Ellis et al 2003).…”

Potato Production near Glyphosate-resistant Crops — Injury Potential

“…Glyphosate drift caused 58% of all drift cases. In general, grass species are more sensitive to glyphosate than broadleaf species; thus, glyphosate drift onto crops such as corn, rice, and wheat can cause significant yield reduction, especially if the drift occurs during a sensitive growth stage [5,13,19,20]. However, the economic loss in these crops may not be as great as from drift to less sensitive high-value broadleaf crops that are consumed with little processing and have no Environmental Protection Agency (EPA) tolerance level, such as many fruits and vegetables.…”