ABSTRACT
A total of six experiments were conducted over a
two-year period (2018, 2019) at the University of Guelph Ridgetown Campus to
assess the efficacy of various herbicides applied postemergence (POST) for the
control of common chickweed in winter wheat. Fluroxypyr/bromoxynil/MCPA, pyrasulfotole/bromoxynil,pyrasulfotole/bromoxynil/fluroxypyr,pyrasulfotole/bromoxynil/
thiencarbazone,
pyrasulfotole/bromoxynil/thiencarbazone + MCPA ester, tolpyralate and fluroxypyr/halauxifen
+ MCPA EHE, applied POST, controlled common chickweed only 5% - 42% at 2 weeks after treatment (WAT) and 1% - 23% at 4 WAT and resulted in common chickweed
density and biomass that was similar to non-treated weedy control. Fluroxypyr/halauxifen
+ pyroxsulam + MCPA EHE, applied POST, provided 57% - 82%
control of common chickweed and reduced density 93% and biomass 98% compared to
the non-treated control. Thifensulfuron/tribenuron,
thifensulfuron/tribenuron + MCPA ester, thifensulfuron/tribenuron + fluroxypyr
+ MCPA ester, tribenuron + thiencarbazone, and tribenuron + thiencarbazone +
MCPA ester, applied POST, controlled common chickweed 98% - 100% and reduced common chickweed density 96% - 98% and common chickweed biomass 99%. Based on
these results, herbicide treatments which contained tribenuron including thifensulfuron/tribenuron,
thifensulfuron/tribenuron + MCPA ester, thifensulfuron/tribenuron + fluroxypyr
+ MCPA ester, tribenuron + thiencarbazone, and tribenuron + thiencarbazone +
MCPA ester were the most efficacious for the control of common chickweed in
wheat. In addition, fluroxypyr/halauxifen + pyroxsulam + MCPA EHE, applied POST, can provide adequate control of common
chickweed in winter wheat.