Peanut Yield and Grade Response to Glyphosate Plus Dicamba

Abstract

Listen

Translate article

Due to the increased adoption of dicamba-tolerant cotton (Gossypium hirsutum L.) and soybean [Glycine max (L.) Merr.], near-by sensitive broadleaf crops such as peanut (Arachis hypogaea L.) are at an increased risk for off-target movement events. Limited data on peanut response to multiple exposure events of reduced rates of glyphosate plus dicamba are available. Therefore, the objective of this study was to determine the impact of multiple exposure events and low rates of glyphosate plus dicamba on peanut yield and grade across multiple locations in the southeast and southwest production regions of the U.S. In 2019/2020, field trials were conducted in seven states (AL, FL, GA, NC, OK, SC, TX). Glyphosate plus dicamba timings were 30 + 60 days after planting (DAP) or 30 + 60 + 90 DAP. Glyphosate plus dicamba rates were 12.6 g ae/ha + 5.6 g ae/ha (1/100X) and 25.2 g ae/ha + 11.2 g ae/ha (1/50X). In the southeast region (AL, FL, GA, NC, SC), peanut yield was not reduced by the 1/100X rate but was reduced 9% by 1/50X rate. Peanut yield was not reduced by any rate or timing in the southwest region (OK, TX). In OK and TX (South), total sound mature kernels were reduced 1% to 4% by the 1/50X rate of glyphosate plus dicamba or when glyphosate plus dicamba was applied 30 + 60 + 90 DAP. Increases in peanut pod malformations (4% to 11%) were observed in GA and NC but this response was not consistent. Multiple off-target exposure events of glyphosate plus dicamba at rates ≤ 1/100X in peanut should not result in significant yield or grade losses but may cause abnormal pod development.