ABSTRACT
There are a
limited number of soil-applied herbicides available for broad-spectrum weed control in dry bean production in Ontario, Canada. Four experiments
were conducted from 2017 to 2019 in southwestern Ontario to compare the
efficacy of six soil-applied grass herbicides [trifluralin (600 g ai ha-1),
ethalfluralin (810 g ai ha-1), pendimethalin (1080 g ai ha-1),
S-metolachlor (1050 g ai ha-1), dimethenamid-p (544 g ai ha-1)
and EPTC (3400 g ai ha-1)] and halosulfuron (35 g ai ha-1)
applied alone and in combination, applied preplant incorporated (PPI), on white
bean tolerance and yield, and weed control efficacy. There was no white bean
injury from the herbicide treatments evaluated.
Grass herbicides (trifluralin, ethalfluralin, pendimethalin, S-metolachlor dimethenamid-P and EPTC) controlled velvetleaf 0% - 82%, pigweeds 87% - 99%,
common ragweed 0% - 93%, common lambsquarters 81% - 99%, wild mustard 0% - 71%,
barnyardgrass 98% - 100% and green foxtail 98% - 99%. Halosulfuron controlled
velvetleaf 98%, pigweeds 94%, common ragweed 90% - 94%, common lambsquarters
97%, wild mustard 98% - 100%, barnyardgrass 19% - 24% and green foxtail 20% -
25%. Tankmixes of halosulfuron with soil-applied grass herbicides provided ≥93%
control of the weed species evaluated. Reduction in density and biomass
generally followed the same trend as visible control with herbicide treatments
evaluated. Weed interference reduced white bean seed yield 70%. Seed yield was
53% - 66% of the weed-free control with
trifluralin, ethalfluralin, pendimethalin, S-metolachlor and
dimethenamid-P, 81% of the weed-free control with EPTC, 58% of the weed-free
control with halosulfuron, and 87% - 95% of the weed-free control with
halosulfuron tankmixes with the grass herbicides evaluated. Based on these
results, halosulfuron in combination with trifluralin, ethalfluralin,
pendimethalin, S-metolachlor, dimethenamid-p and EPTC, applied PPI at rates
evaluated, can be used to effectively control common annual grass and broadleaf
weeds in white beans.