Soybean School: Herbicide tips for planting soybeans after winter wheat failure

OMAFRA weed specialist Mike Cowbrough

Winter is not always kind to fall-planted wheat. Sometimes thin stands and winter kill make for a poor economic outlook and growers need to take it out and plant another crop.

What do growers need to think about if they decide to switch to soybeans? Are there implications if a cereal herbicide had been applied in the fall or spring? On this episode of the RealAgriculture Soybean School, we visit with Ontario Ministry of Agriculture, Food and Rural Affairs weed specialist Mike Cowbrough at a herbicide trial designed to help answer these questions.

In general, Cowbrough says there is little information available about the impact of specific cereal herbicides on soybeans where the oilseed has been planted after an abandoned winter wheat crop. Cowbrough’s research trial, at the Elgin Soil & Crop Improvement Association research site near St. Thomas, Ont., was designed to generate data that could be used to recommend label statements that could address the potential for injury.

In the video, as Cowbrough inspects the research plots, he sees no injury to several soybeans plots that had common cereal herbicides applied on the day the seed was planted, what he calls a high-risk scenario for damaging plants. But as he walks through the research trial, a plot catches his eye: “There is one particular herbicide that is a no fly zone that causes way too much injury,” he says.

That active ingredient is clopyralid, found in products including Lontrel and Prominex. He notes that clopyralid is labelled for field corn and if growers need to take out wheat that has been sprayed with this active, they can safely switch to field corn.

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