Postemergence Efficacy of Pyroxasulfone at Different Rates and Timings in Wheat

Abstract

Pyroxasulfone is a VLCFA inhibitor labeled to control grasses and small-seeded broadleaf weeds. Little information is available regarding this herbicide being applied postemergence. Two field experiments were conducted to evaluate the efficacy of pyroxasulfone used postemergence. Pyroxasulfone applied to 2-leaf wheat controlled up to 83% of the green foxtail but had little to no effect on broadleaves. An additional field study was conducted to determine if pyroxasulfone could give supplemental green foxtail control when tank-mixed with ALS inhibitors. Few tank-mix combinations increased control, and the tank-mixes that did had inadequate control, <70%. Greenhouse experiments were also conducted. The first concluded that a wide range of grass species are susceptible to pyroxasulfone applied postemergence. The second demonstrated weed control with pyroxasulfone is almost exclusively due to root uptake. Contradicting levels of control between field and greenhouse experiments suggests more information is needed before pyroxasulfone can be utilized as a postemergence herbicide.