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Issue No. 11, Article 3/June 4, 2004

Corn Rootworm Hatch Confirmed

In the article titled "Corn Rootworm Hatch: Just Around the Corner?" (issue no. 8, May 14, 2004), Mike Gray discussed the historical accounts of corn rootworm hatch in the Midwest as well as predicting the occurrence of corn rootworm hatch based on the projected heat unit accumulations. After speculation of when corn rootworm hatch will occur, the first report is in.

Jim Donnelly, with Ag View FS, conducted a few root floats over the Memorial Day weekend, finding one lone rootworm larva. The rootworm larva was located in a corn-on-corn field, in southwestern Lee County (northeast of Walnut).

Corn rootworm larva. (Photo courtesy of Jim Donnelly, Ag View FS.)

Current degree-day totals (base 52°F, 4-inch soil temperature), from January 1 to June 1, indicate that much of the state of Illinois should be experiencing corn rootworm hatch (Figure 1). As noted in the aforementioned article, research has shown that after 380 to 426 soil heat units (base 52°F, 4-inch soil profile) have accumulated, from January 1, approximately 50% of corn rootworm larvae should have hatched.

--Kelly Cook

Kelly Estes

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