Response of insect pest and beneficial species to the timing and severity of dicamba injury in soybean
Abstract
Off-target movement (OTM) of dicamba (3,6-dichloro-2-methoxybenzonic acid), to sensitive crops has been one of the most significant issues to affect non-dicamba-resistant (non-DR) soybean (Glycine max (L.) Merr.) production in recent years. Although the yield response of non-DR soybean to OTM of dicamba has been extensively studied, few studies have been conducted to understand the effects that dicamba injury has on insect infestations in non-DR soybean. A field experiment was conducted at four locations in Missouri in 2018 and three locations in 2019 to determine if dicamba injury to non-DR soybean has any effect on the prevalence of insect species throughout the growing season. At each location, dicamba was applied to non-DR soybean at rates corresponding to 1/10th, 1/100th, 1/1,000th, and 1/10,000th of the labeled used rate (560 g ae ha-1) at either the V3 or R1 stage of growth. In this study, dicamba doses associated with vapor drift resulted in increased visitation to soybean from bean leaf beetle (Cerotoma trifurcata). However, the most common response was reduced insect visitation after V3 or R1 applications of dicamba at 1/10th or 1/100th the labeled rate compared to the non-treated control. This response is likely related to the reduction in soybean growth and biomass observed following treatment with the higher rates of dicamba, which in turn influenced the habitat preferences exhibited by the species observed in this study. As the use of dicamba increases in U.S. soybean production, it is important to understand the effects OTM of dicamba has on insect species in agricultural production environments.
Degree
M.S.
Thesis Department
Rights
OpenAccess.
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