Efficacy of HPPD-inhibiting herbicides applied preemergence or postemergence for control of multiple herbicide resistant waterhemp [Amaranthus tuberculatus (Moq.) Sauer]

Abstract

Research was conducted in 2017 and 2018 to determine the relative efficacy of five HPPD-inhibitors, tank-mixed with atrazine, for the control of multiple herbicide resistant waterhemp. At 12 wk after application (WAA), isoxaflutole + atrazine, mesotrione + atrazine, and tembotrione + atrazine, applied preemergence (PRE), controlled waterhemp 90%, 87%, and 81%, respectively. None of the HPPD-inhibiting herbicides applied PRE controlled waterhemp similar to the weed-free control 12 WAA. Applied postemergence, topramezone + atrazine, mesotrione + atrazine, tolpyralate + atrazine, and tembotrione + atrazine controlled waterhemp 87%, 94%, 97%, and 98% 12 WAA, respectively, and were all similar to the weed-free control.