Soybean School: Herbicide synergy powers up weed control


Some herbicides aren’t very effective at controlling a weed like horsetail, but when you combine two poor-performing products, they can deliver a surprising level of control. In weed science terms, this ability of different active ingredients to team up and deliver a knockout blow is called herbicide synergy.

On this episode of the RealAgriculture Soybean School, Ontario Ministry of Agriculture, Food and Rural Affairs weed specialist Mike Cowbrough shares how different herbicides have a synergistic effect and can work together to better control weeds, including field horsetail and common ragweed in soybeans.

In the video, Cowbrough and host Bernard Tobin visit Ontario’s Elora Research Station to look at a research trial conducted by University of Guelph weed scientist Dr. Francois Tardif.

Cowbrough notes that the introduction of new herbicide-tolerant soybean varieties opens up the possibility of combining different chemistries to control these weeds. When some of the chemistries are combined they deliver good top growth control to effectively keep the pests in check through the critical weed-free period for soybeans or corn.

Touring Tardif’s trial, Cowbrough notes how control of the two weeds is poor when only glyphosate is sprayed. Top growth control for horsetail, however, does improve when 2,4-D choline, Enlist 1 herbicide, is combined with glyphosate.

Cowbrough notes that control moves up another level when glufosinate ammonium, the active in Liberty herbicide, is combined with 2,4-D choline, creating even more synergistic and effective weed control. See the video below.

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