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News Insect Pests
Peak season for insect pressure in Ontario


August 12, 2019
By Field Crop News

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It is peak season for pests such as western bean cutworm, corn rootworm, corn earworm, and Japanese beetles, according to the latest crop report from Ontario’s Ministry of Agriculture, Food and Rural Affairs (OMAFRA).

The OMAFRA field team has provided a breakdown on each pest, how to scout for them, and what factors go into a decision to spray.

Highlights from the latest crop report include:

  • Peak moth flight for western bean cutworm (WBC) is underway, putting both corn and dry beans at risk. WBC moths prefer pre-tassel to full tassel corn to lay eggs in so producers are encouraged to scout these fields first.
  • Moths of corn earworm have been captured in Ontario and neighbouring jurisdictions for several weeks now. While scouting for WBC, producers should watch for signs of CEW ear feeding, usually noticeable if silks appear thin or absent.
  • Adults of corn rootworm are abundant in many corn fields. A spray is required if adults are clipping silks to 1.25 cm or less, and 10 or more adults per plant are present before 50 per cent pollination.
  • Japanese beetles are also abundant this year and like rootworm, can clip corn silks. If there are three or more beetles per plant and silks are being clipped to 1.25 cm or less before 50 per cent pollination, a spray is warranted.
  • Both rootworms and Japanese beetles can feed on soybeans, but regardless of which insect is feeding on soybean leaves, it’s the percentage of defoliation that matters.

Read more in the latest crop report from OMAFRA’s field crop team.