Corn School: Knee-high, now what?

All the “knee-high by the first (or fourth) of July” photos have been posted on social media, with the crop looking nice from above; but what’s going on below the canopy?

Now is the time to check weed populations and assess herbicide performance, says Jeanette Gaultier, senior technical services specialist with BASF, joining us for this Western Canada-focused episode of RealAgriculture’s Corn School.

“Definitely be out checking weeds. You want to know what spectrum you have to make the best herbicide choices,” she stresses.

Due to wet conditions lingering from last fall, and a delayed start to planting corn in the corn-growing areas of the Prairies this spring, some fields did not receive a pre-seed herbicide application.

“Definitely when we skip that pre-seed, when we go with our in-crop, we are dealing with larger weeds and higher weed pressure. It really doesn’t set up the in-crop herbicide well,” she says, noting lamb’s quarters and kochia have been increasing in prevalence, along with the regular warm-season grasses.

Gaultier stresses the importance of throwing something else in the tank with glyphosate.

“Corn is a great opportunity to get away from your Group 1 and Group 2 rotation, and throw in some unique modes of action,” she says.

Now is also a good time to assess brace root development, says Gaultier, noting there have been higher-than-normal reports of leaning or floppy corn this growing season.

There are a number of potential reasons for this, she explains, including rapid growth syndrome as cool spring conditions quickly turned warm a few weeks ago. Blustery winds and wet soil conditions inhibiting root growth have also contributed to increased leaning, notes Gaultier.

As for questions about spraying corn when it’s leaning or appearing stressed, she says weed control is critical for maintaining yield potential, so she would not recommend skipping a herbicide application.

“It’s about putting on the right rate at the right timing,” she says.

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