Cotton Weed Management Systems in Conventional and Conservation Tillage

Weed management trials were established near Lubbock, TX in 2017 and 2018 to compare systems in both conventional and conservation tillage. Four herbicide systems were included for both the conventional and conservation tillage. Conventional tillage treatments included trifluralin preplant incorporated (PPI) followed by (fb) no preemergence (PRE) fb dicamba + glyphosate + acetochlor early postemergence (EPOST) fb dicamba + glyphosate midpostemergence (MPOST), trifluralin PPI fb prometryn PRE fb dicamba + glyphosate EPOST fb dicamba + glyphosate + acetochlor MPOST, no PPI fb prometryn PRE fb dicamba + glyphosate EPOST fb dicamba + glyphosate + acetochlor MPOST, trifluralin PPI fb prometryn PRE fb glyphosate EPOST fb glyphosate + acetochlor MPOST. Conservation tillage treatments included dicamba + glyphosate early preplant (EPP) fb paraquat + prometryn PRE fb dicamba + glyphosate EPOST fb dicamba + glyphosate MPOST, dicamba + glyphosate + flumioxazin EPP fb paraquat + prometryn PRE fb dicamba + glyphosate EPOST fb dicamba + glyphosate MPOST, glyphosate EPP fb dicamba + prometryn fb dicamba + glyphosate EPOST fb dicamba + glyphosate MPOST, no EPP fb dicamba + prometryn fb dicamba + glyphosate EPOST fb dicamba + glyphosate MPOST. Visual weed control for Russian thistle, kochia, and Palmer amaranth was recorded at cotton planting and 14 days after planting. Palmer amaranth control was recorded at 14 and 28 days after the EPOST and MPOST treatments. Effective season-long control of Palmer amaranth (>98%) was achieved using various dicamba-based herbicide systems in both conventional and conservation tillage. Glyphosate-based herbicide systems controlled Palmer amaranth <53% in 2017 and <84% in 2018 due to the number of glyphosate-resistant weeds present. All dicamba treatments controlled Palmer amaranth >83% in 2017 and >98% in 2018.