Corn School: Managing western bean cutworm


It’s lining up to be a big corn pest year and the insect to watch for in the weeks ahead is western bean cutworm (WBC).

In this edition of RealAgriculture Corn School, OMAFRA entomologist Tracey Baute explains that late planting across Ontario has left the young corn crop more susceptible to an increased number of pests. In the video, she takes a look at how pests such as billbugs and stinkbugs have taken advantage of the cool, wet early growing conditions to take a bite out of corn plants.

Pesky billbugs have been taking bites out of corn plants across Ontario. Photo: Dominic Reisig, NC State University

But Baute focuses the majority of her insights on how growers can best control and manage the impact of WBC. She’s expecting significant pressure this year because delayed planting has allowed for “most of the crop to be at the ideal crop stage for the moths to want to lay their eggs.” Peak flight usually happens the last few weeks of July and the first week of August and that’s when they’ll be looking for that pre-tassel/tassel stage to lay their eggs.”

Growers really need to get out and scout for eggs to see if they have reached threshold, says Baute. She warns that all fields across the province are at risk and growers should use traps to determine if WBC is present in their area of Ontario. “Don’t assume because you are outside the hotspot of Bothwell and Tillsonburg that you’re not at risk,” she stresses.

Baute notes that the big concern with WBC is not so much yield impact, but rather the role they can play in the introduction of ear moulds and mycotoxins. “You not only want to spray with an insecticide to control the insect, but you also want to protect the crop with a fungicide.” She recommends spraying an insecticide-fungicide tank mix just as the silks are emerging.

For more on WBC insecticides check out the week’s WheatPete’s Word.

Click here for more Corn School episodes.

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