Corn School: Western bean cutworm still a threat in late-developing crop

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Western bean cutworm (WBC) moths typically hit peak flight this week in Ontario — but not this year.

Cold, wet spring conditions across the province not only delayed crop planting and development but also put the squeeze on the mating and flight patterns of the yield-robbing pest. On this episode of RealAgriculture’s Corn School, Ontario Ministry of Agriculture, Food and Rural Affairs entomologist Tracey Baute says WBC is behind schedule, but they’re coming.

Baute notes that while wet conditions delayed planting, WBC, which overwinters in the the soil, fell victim to the cold spring conditions that limited Growing Degree Day accumulation. With those cold soils, the pests were slow to emerge and, just like most crops, have been playing catch up.

Baute is warning growers not to get lulled into a false sense of security because it’s late July and they haven’t yet seen moths in their field. She reminds growers that with both the crop and the pest running three weeks to a month behind schedule, it’s likely peak moth flight will still occur at the pre-tassel to full-tassel stage of development in many corn fields across the province.

While scouting timing will change this year, Baute says growers still need to follow established scouting and control protocols. If eggs are found on five of 100 plants, the field is at economic threshold and a spray is recommended.

In the video, Baute also discusses foliar insecticide options. She notes that there are four control products available and encourages growers to rotate insecticides annually to help manage the potential for insecticide resistance in WBC.

Click here for more Corn School episodes.

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