Edible Bean School: Controlling post-emergent weeds

Hensall Co-op agronomist Josh Moffatt

As edible bean planting wraps up across Ontario, grower focus shifts to controlling post-emergent weeds and grasses.

When seed is planted to moisture, in warm soils, growers and agronomists will need to get out and scout to determine what competition, including small and actively growing weeds, the emerging crop will encounter.

On this episode of RealAgriculture’s Edible Bean School, Hensall Co-op agronomist Josh Moffatt stresses that small weeds are much easier to kill than big ones. “You might see a little bit of crop injury from coming in early [with a herbicide] before that first trifoliate stage with edible beans, but the weed control is much more of a concern than a little bit of crop injury early on edible beans,” he says.

One of the keys to effective post-emergent control is the time of day a herbicide is applied. When it comes to using products like Reflex and Basagran, Moffatt says the best time to hit weeds, especially in fields with high pressure, is when it’s sunny and hot.

Water volume is another success factor. “With all post-emergent herbicides I want to use a lot of water, so 20 gallons is kind of a bare minimum that I recommend for most growers — 25 gallons is better. And, sometimes in extreme cases, up to 30 gallons is a good idea.” (Story continues after the video.)

Moffatt also advises growers to consider a drift and deposition agent. “Something like InterLock works really well at making even droplets and just helping that coverage to make it better weed control,” he notes.

In the video, Moffatt shares tips on choosing the right surfactant and identifies products that can cause problems for specific classes of beans. “Basagran and Permit are two things that you do not want to spray on adzukis. Sometimes you’ll see them hold those adzuki beans back a little bit, or maybe even keep them flowering.”

When it comes to grasses, Moffatt notes that glyphosate can no longer be used as a pre-harvest desiccant in many bean classes so growers have to get good control early in the season. He shares several strategies including a two-pass program to avoid the tank antagonism that can occur when mixing grass herbicides with broadleaf control products like Reflex and Basagran.

Tap here for more Edible Bean School videos.

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