While you may have dealt with Japanese beetles invading your garden, they’re now starting to move into agricultural fields. At the Stanton, MN, Agronomy in Action site, we recommend scouting the entire field to give you the best view of how much pressure is present.
Japanese beetles overwinter as grubs in the soil, pupate in spring and emerge as adults in June or July. Beetles feed on the leaves of corn, soybeans and a wide variety of other plants. They can cause extreme defoliation, and if your crops are under stress, their feeding may cause yield loss. Beetles can be identified by the following:
- Metallic green head with brown wings
- White tufts of hair on each side of abdomen
Gauge beetle pressure by sampling your fields. University of Minnesota recommends taking defoliation counts from 10 or more plants throughout the entire field, versus limiting yourself to just one area. Determine the average across 3 leaves and then across multiple plants. Use this table to estimate percent defoliation for each leaf of the plant and identify treatment thresholds based on growing stage. Twenty percent defoliation typically warrants treatment.
Management of this pest can be tricky. The Japanese beetle feeds on such a wide variety of plants that they can be tough to control.
- Manage them in other crops and ornamental plants.
- Apply an insecticide. Be sure to continue scouting after initial application, as you may need another if the pest persists.
The mobility of these pests can make them tough to manage. For tips on how to handle Japanese beetles and more in your fields, contact your Golden Harvest Seed Advisor.
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