Soybean School: Should you plant now and spray later?


With fields drying out and warming up soybean planting is moving full steam ahead in Ontario.

In many cases the spring conditions are dictating that farmers take a ‘plant now, spray later’ approach. It’s an obvious choice, but the challenge for many is how to manage fast-growing, large weeds that can quickly take a bite out of yield potential and cause further management headaches down the road.

In this episode of the RealAgriculture Soybean School, BASF technical development manager Rob Miller talks about how to best manage problem weeds during an abbreviated planting period where soy and corn weed control and planting (as well as cereal fungicide application!) all have to happen in a very narrow timeframe.

“Once those soybeans emerge there are very few options to control those tough-to-control weeds like dandelion, sow thistle and Canada fleabane, especially the glyphosate-resistant types,” says Miller who notes that new work by University of Guelph research scientist Dr. Clarence Swanton indicates that the critical weed free period for soybeans really begins at emergence and continues to the third trifoliate.

See Related Soybean School: Starting clean more critical than ever

“Now that we’re finally getting some heat and a little bit of sunshine we’re going to see a lot more of those annual weeds emerging with the soybean crop,” says Miller. That why it’s important to use a residual herbicide, he adds.

Time is tight, but Miller notes that growers who manage to get down residual herbicides will get better control and also have a more manageable workload in early June when spraying fungicide on wheat will command their attention.

When it comes to managing tough weeds, especially glyphosate resistant Canada fleabane, high water volume is key. Miller recommends spraying 20 gallons per acre at a minimum.

“You also need multiple modes of effective action,” says Miller. “Whatever your target weed species is, you want to have two modes of action in the tank to have activity on that problem weed.”

Click here for more Soybean School episodes.

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Soybean School (view all)Season 6 (2017) Episode 21

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