Silk-clipping beetles in sweet corn

In late July and early August in Ohio, many sweet corn fields are not being threatened by either of the two key pests, the corn earworm and the European corn borer, thus it might seem as if there is no need for insecticide sprays. However, growers should be checking on the presence of silk-clipping beetles: primarily the western corn rootworm beetle and the Japanese beetle, and also the southern corn rootworm beetle and the northern corn rootworm beetle. The critical time to scout for these beetles is during the early silk stage, as pollen is being shed. Examine 50 ears in small plantings (< 2 acres) or 100 ears in large plantings (> 2 acres). Treatment by spraying insecticide to prevent silk clipping by beetles is needed during the early-silk stage if the average number of beetles is 2 or more Japanese beetles per ear or 5 or more corn rootworm beetles per ear.

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