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Issue No. 13, Article 5/July 2, 2010

Scattered Reports of Western Corn Rootworm Adults: Japanese Beetles Clipping Silks in Some Illinois Areas

To date, I have received very few reports of western corn rootworm adults being found in cornfields. Joe Spencer, an entomologist with the Illinois Natural History Survey, did find a male western corn adult in his plots north of Urbana approximately 2 weeks ago. Mike Roegge, University of Illinois crop systems extension educator, reported that western corn rootworm adults are present in some western Illinois (Adams County) cornfields. In our research plots south of Urbana, we have not yet found any adults in our emergence cages. However, I suspect that emergence will begin to pick up after the July 4 holiday. We anticipate beginning our annual root "digs" the week of July 12.

Japanese beetles clipping silks in Massac County, June 25. (Photo courtesy of Ron Hines).

Japanese beetles are being found throughout the state. In some areas of Illinois, especially southern counties, Japanese beetles can be found clipping silks in certain fields. Ron Hines observed some significant clipping in Massac County on June 25. Such observations will likely increase in other areas of the state as more fields move into the reproductive phase of development. Before making any management decision regarding Japanese beetles, make sure your scouting efforts include areas of the field beside border rows, where densities are typically more intense. A rescue treatment should be considered if 3 or more beetles per ear are found and pollination is still under way. I encourage producers to begin scouting for Japanese beetles in both corn and soybean fields. If defoliation within a soybean field reaches 30%, consider a rescue treatment.--Mike Gray

Mike Gray

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