TITLE:
Using Pyroxasulfone for Downy Brome (Bromus tectorum L.) Control in Winter Wheat
AUTHORS:
Vipan Kumar, Prashant Jha, Amit J. Jhala
KEYWORDS:
Downy Brome, Pyroxasulfone, Soil-Applied Herbicide, Herbicide Rate, Application Timing, Formulation, Wheat
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.10,
September
6,
2017
ABSTRACT: Downy brome is one of the most troublesome weeds in no-till
wheat production systems of the US
Great Plains. Pyroxasulfone
is a relatively new, soil-applied residual herbicide (root/shoot growth
inhibitor) labeled for use
in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield™) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the
three studies. Downy
brome injury with pyroxasulfone preemergence
(PRE) only program did not differ between 89 or 178 g·ai
(active ingredient)·ha-1 rates,
and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown
program, the addition of pyroxasulfone (178 g·ai·ha-1) to
glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE
(84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water
dispersible granule (WDG) formulation of pyroxasulfone performed slightly
better than the suspension concentrate (SC) formulation for downy brome injury.
Pyroxasulfone applied
PRE in the fall at a rate of 89 g·ai·ha-1 followed by (fb) imazamox
(44 g·ai·ha-1 rate)
applied postemergence (POST) in the
spring effectively controlled downy brome (99% end-season injury). Furthermore,
the injury was consistent with the standard program comprising of propoxycarbazone (29 g·ai·ha-1) PRE
fb imazamox
POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized
in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST
herbicide program for a season-long downy brome management in winter wheat.