Multiple modes of action kills weeds, prevents resistance

Growers have long been told they need to rotate herbicide modes of action and even use multiple modes of action at the same time to slow the development of herbicide resistant weeds in their fields.

“In terms of reducing your risk of resistance development, it’s an exponential decrease from your risk of having a weed develop resistance if you use more than one mode of action,” Graham Collier of Nufarm said at the Farm Forum Event in Calgary late last year.

Collier said a goal for Nufarm is to offer affordable ready-made formulations to make it as easy as possible for farmers to attack weed populations with multiple modes of action.

“Basically, our approach is multiple modes of action being used in a pre-seed burn-down, or a pre-emergent application or in some cases in the fall, before seeding in the spring,” he said.

“What we want to do is include modes of action at those times that we can’t necessarily use in crop.”

He said including a Group 14 chemical in the herbicide regime has proven a good option as another mode of action to get into the rotation because there is a synergy between Group 14 and Group 6 that make this mixture especially effective.

This is because they use a similar method to kill the plant, which is singulate oxygen.

“What singulate oxygen does is it tears the cell membrane apart, and that causes the contents to leak out and dry and you get that really dry and crisp brown symptomatology appearing on the leaves, that quick necrosis,” Collier said.

He said there is a greater efficacy than with either product alone because both modes of action kill the plant in the same way but do it from two totally separate systems within the plant.

Collier said Nufarm’s Conquer has both Group 14 and Group 6 active ingredient, and when mixed with glyphosate, produces a burn-down that cleans up resistant kochia, cleavers and volunteer canola yet is safe to use before seeding canola.

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