Peanut (Arachis hypogea) Response to Low Rates of Dicamba at Reproductive Growth Stages

Tank contamination and off-target movement of dicamba is a probable issue facing peanut producers in Mississippi. In 2017 and 2018, a field study was conducted at Mississippi State University’s Delta Research and Extension Center in Stoneville, Mississippi, to evaluate the response of peanut to low rates of dicamba at three growth stages. Dicamba at 35 and 17.5 g ae ha−1 with and without non-ionic surfactant (NIS) was applied to peanut at R1 (beginning bloom), R2 (beginning peg), and R3 (beginning pod). In each site year, peanut injury was visible following exposure to dicamba. Peanut lateral growth was also reduced regardless of treatment or growth stage following exposure to dicamba. Peanut injury was most prominent 14 days following exposure to dicamba, regardless of timing in both site years. Peanut yield was not different following dicamba treatments in 2018 due to late-season environmental conditions. In 2017, dicamba at 1/32 X plus NIS, 1/16 X and 1/16 X plus NIS reduced peanut yield 16%, 16%, and 30% when averaged over growth stage, respectively. Based on this study, visible peanut injury, lateral growth reduction, and yield decreases were observed following exposure to dicamba.