Peanut response to 2,4-D plus glyphosate

摘要

Abstract The commercialization of crops that are resistant to 2,4-D plus glyphosate provided an opportunity to growers to apply the herbicide postemergence. However, the potential drift injury of these herbicides to peanuts grown near crops that are resistant to 2,4-D plus glyphosate is concerning. Field experiments were conducted in 2019 and 2020 to evaluate peanut response when exposed at 25, 50, and 75 d after planting (DAP) corresponding to vegetative, flowering, and pod development stages, respectively, to reduced rates of 1/512×, 1/128×, 1/32×, and 1/8× of the labeled rate of 2,4-D plus glyphosate (i.e., 1,077 + 1,132 g ae ha−1, respectively). 2,4-D plus glyphosate was more injurious to peanuts when exposed at 25 DAP compared with 50 and 75 DAP. Similarly, greater canopy height (12) and canopy width (16) reductions were observed at 25 DAP compared with 50 and 75 DAP exposure timings (3 to 9). This result indicates that peanut is more sensitive to 2,4-D plus glyphosate exposure at the vegetative growth stage than at the flowering and pod development stages. However, yield reductions (13 to 16) were not different between 25, 50, or 75 DAT exposure timings. Regression analysis indicated a linear response for peanut injury, canopy height, width, and yield reduction with an increasing rate of 2,4-D plus glyphosate. The highest rate of 2,4-D plus glyphosate (1/8× of the label rate) resulted in 38, 22, and 23 peanut injury, canopy height, and width reduction at 4 wk after treatment, and 33 yield reduction. There was a correlation between peanut injury and yield reduction, with Pearson’s rho values ranging from 0.70 to 0.73. The findings suggest that peanut injury rating data after 2,4-D plus glyphosate drift can be useful for estimating potential yield losses.