Benefit To Soybean Farmers
Palmer amaranth, common ragweed, common waterhemp and marestail continue to pose significant challenges to soybean producers in Maryland. Studies during in recent years have identified best practices for management of herbicide resistant weeds including examination of novel herbicide tolerance traits, most effective herbicide combinations, application timing and residual products. Past research has demonstrated the effective termination of herbicide resistant weeds such as Palmer amaranth, common ragweed, common waterhemp and marestail prior to soybean emergence is critical for maintaining yield potential throughout the season. This study will evaluate efficacy of several herbicide treatments for control of herbicide resistant weeds prior to soybean emergence. Burndown treatment options have expanded in recent years with the addition of the herbicide tolerant platforms Enlist E3, Xtendflex, and Libertylink.
There are a number of factors for wanting to perform this work. First, the availability and price of glyphosate and glufosinate has risen substantially. Farmers are interested in replacing glyphosate in the burndown program with the other products under review. In addition, a common question asked by farmers dealing with herbicide resistant Palmer amaranth is: What are the most effective burndown options in situations where Palmer amaranth is larger then the ideal 3-4 inch control range?” We often encounter this scenario in fields left fallow for a year, fields with delayed planting due to saturated soils, and double crop fields following wheat. Finally, farmers are reporting issues with 2,4-D controlling Palmer amaranth that is past the 6-8 inch height window. In trials in 2022, 2,4-D performed poorly in late double crop planting window for burndown of Palmer amaranth.