Soybean School: Watch for pests as July turns dry

After a wet spring, the weather has turned hot and dry in Ontario and that could mean a proliferation of pests in soybean fields across the province.

On this episode of RealAgriculture Soybean School, Ontario Ministry of Agriculture, Food and Rural Affairs entomologist Tracey Baute says a change in the weather will likely bring on the bugs.

Baute is already seeing thrips in soybeans. The tiny cigar-shaped pests invaded some Ontario corn fields in 2018 and now they’ve taken a fancy to the province’s leading oilseed crop. In soybeans, thrips injury can often be seen along the veins of the leaves. There’s little information about how to manage the pest in soybeans, but based on the best available information, Baute says if 75 percent of the plants in a field have thrips (eight pests per plant), and they’re not growing out the injury, growers may need to spray.

Spider mites also like the drier conditions. When these minuscule pests set roots in a field, plant leaves look like they’ve been sand blasted. It takes only four mites per leaflet or one severely infested plant to justify a spray. (Story continues after the video.)

Baute is telling growers to get out and scout their fields — “you’ll never know what you’ll find,” she says. While shooting this video, she spied several Japanese beetles in test plots at the Ridgetown College location. Japanese beetles like both soybeans and corn, especially at silking. She says the beetles, which can significantly defoliate soybeans plant leaves, are most active in the crop during the bloom to early pod setting stages.

Click here for more Soybean School episodes.


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