TITLE:
Activity of Isoxaflutole plus Metribuzin Tankmixes in Isoxaflutole-Resistant Soybean
AUTHORS:
Andrea Smith, Nader Soltani, David C. Hooker, Darren E. Robinson, Allan C. Kaastra, Peter H. Sikkema
KEYWORDS:
Glyphosate Resistance, HPPD Transgenic Soybean Cultivars, Preemergence Herbicides, Rainfall, Soybean Yield, Weed Management
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.10 No.8,
August
26,
2019
ABSTRACT: Isoxaflutole-resistant soybean is currently in
development for commercialization in North America. Proposals to use
isoxaflutole + metribuzin as the main herbicide tank-mixture raise concerns as
there is limited grass control with these herbicides. Strategies are needed to
improve grass control with isoxaflutole + metribuzin. Nine
experiments were conducted over a two-year period (2017, 2018) to determine the efficacy of
isoxaflutole + metribuzin (52.5 + 210 g a·i· ha-1) applied alone and co-applied
with pendimethalin, dimethenamid-P, pethoxamid,
pyroxasulfone or S-metolachlor applied preemergence (PRE).
Comparisons were made with isoxaflutole + metribuzin at a low rate (52.5 + 210 g a·i· ha-1), medium rate (79 + 315 g a·i· ha-1) and
a high rate (105 + 420 g a·i· ha-1). Eight weed species were
evaluated including common lambsquarters,
green and redroot pigweed, common ragweed, velvetleaf, green and giant foxtail,
yellow foxtail, barnyardgrass and witchgrass. All herbicides were
affected by amount of rainfall following
application; less rainfall resulted in reduced weed control. The addition of pendimethalin, dimethenamid-P, pethoxamid,
pyroxasulfone or S-metolachlor to the low
rate ofisoxaflutole + metribuzin provided
equivalent control of all weed species evaluated compared toisoxaflutole + metribuzin at the low, medium,
or high rate.