By Owen Roberts, FCC Express
Peter Sikkema of the University of Guelph’s Ridgetown campus, told farmers at a recent meeting in Wallaceburg, Ont. that one mode of action is no longer enough to fight weeds.
Wallaceburg is central to a great deal of the corn and soybean acreage in southwestern Ontario, where pockets of resistance are starting to show. Sikkema says weed management in soybean crops is better achieved – and provides residual weed control quickly – when tank-mix partners are added to glyphosate, to deliver a second mode of action.
“This means weeds are not competing with the crop during that early period of crop development,” he says.
It’s cause for concern, with glyphosate resistance on the rise. Sikkema told the Wallaceburg meeting the number of glyphosate-resistant Canada fleabane sites has jumped from eight in 2010 when it was first reported, to 155 in eight counties last year.
As well, more than 70 sites of glyphosate resistant giant ragweed have been confirmed in Ontario, as well as one site of glyphosate-resistant common ragweed, in Essex County.
At some point, certain members of any given weed population will naturally develop resistance to herbicides. The likelihood of resistance increases when the same mode of action is used repeatedly, eliminating the opportunity for other modes to keep resistant-prone weeds in check.