Tillage, Rotation and Herbicide Input Impact Weed Control in Xtendflex Cotton

Field research was conducted during 2019 and 2020 in irrigated (College Station) and dryland locations (Thrall and Corpus Christi) in Texas to determine the influence of tillage, crop rotation and dicamba-based herbicide programs on weed control in XtendFlex cotton. Herbicide programs include a non-treated check, weed-free check, Low input program with EPOST and LPOST applications, and a High input program with PRE, and MPOST applications. Experiments were arranged as a split-split plot design with the cover crop, strip till and conventional till as main plots, and cotton-cotton and cotton-sorghum rotations as sub plots in each tillage. Four levels of herbicide program represented sub-sub plots. Based on data in hand from College Station and Thrall, a significant four-way interaction was observed at 14 DA PRE timing for Palmer amaranth control between location, year, tillage and crop rotation. In 2019, at both locations, more than 90% control was observed in both cotton-cotton and cotton-sorghum rotation plots across all tillage practices. At College Station, conventional till provided the highest control of Palmer at more than 97% during both. In 2020 at College Station, strip till provided 26% and 52% control in cotton-cotton and cotton-sorghum rotation treatments respectively. At Thrall, cover cropping gave more than 98% control of Palmer both years, while in 2020, strip till provided 89% and 85% control in continuous and rotation plots respectively. Tillage and herbicide program influenced the emergence of Palmer during 2020. Application of residual herbicide PRE reduced the emergence of Palmer by more than 50% compared to the low input program in all the tillage practices at both the locations. Palmer emergence was 0 until two months after planting in both low and high input treatments of conventional tillage at Thrall and cover cropping showed the greatest effect on emergence of Palmer at College Station.