Economics and Efficacy of Weed Management in Bollgard II Xtendflex Cotton

Managing glyphosate-resistant Palmer amaranth (Amaranthus palmeri) has increased weed management costs for Texas High Plains cotton producers. The introduction of Bollgard II XtendFlex (dicamba-tolerant) varieties and registration of dicamba formulations for postemergence use in cotton, combined with residual herbicides, can effectively control Palmer amaranth. It is estimated that 60-70% of the region’s cotton acreage was planted in Bollgard II XtendFlex varieties in 2018. To maintain this technology, proper use of residual herbicides is essential. Field studies were conducted in 2018 and 2019 at Lubbock to evaluate Palmer amaranth control and weed management cost for XtendFlex, LibertyLink, Roundup Ready, and conventional cotton systems for irrigated and dryland production.