LibertyŽ and Residual Herbicide Systems for Palmer Amaranth Management

GlyTol^® LibertyLink^® is the first double-stacked herbicide tolerant technology providing tolerance to both Liberty^® 280 SL (glufosinate) and glyphosate herbicides. This technology allows growers to make over-the-top applications with two modes of action to effectively control weeds and reduce the potential for resistance as part of a comprehensive, full-season herbicide program. Increasing populations of glyphosate-resistant Palmer amaranth require new postemergence weed management options. In the Texas High Plains, studies were conducted in 2015 at four sites to evaluate control of partially resistant Palmer amaranth populations in GlyTol^® LibertyLink^® cotton following single and sequential applications of Liberty^® with and without Dual Magnum^® or Roundup PowerMAX^®. Applications were made at 15 GPA using Turbo TeeJet® 110015 nozzles at 38 PSI. Results showed that Liberty^® effectively controlled Palmer amaranth where applied POST to 4-6” tall weeds and that effective season long control (95-100%) was observed when sequential POST applications of Liberty^® + Dual Magnum^® were applied. When Liberty^® was applied in tank-mixture with glyphosate antagonism was observed. In 2015, weather conditions during the first half of the growing season (above average rainfall, higher humidity, and below average temperatures) influenced Liberty^® activity in the Southern High Plains.