No. 3 Article 2/April 14, 2006

Black Cutworm Flights Getting in Full Swing

During the last 10 days, we have had several reports of black cutworm moths caught in pheromone traps. Ron Hines, senior research specialist at the Dixon Springs Agricultural Center, has his trap line up and running. Black cutworm moths have been identified in four traps (Jefferson, Pope, Pulaski, and St. Clair counties), with Pulaski County recording the only intense capture thus far in the season during the week of March 27. However, reports have come in from counties farther north and west as well: moths have been captured in Coles, Cumberland, Piatt, and Adams counties.

As corn planting begins to coincide with moth flights, it's important to scout fields that are especially attractive for egg laying. Fields or portions of fields where early-season weeds were growing when moths flew into the area are at higher risk than weed-free fields. If tillage or herbicides eliminate weeds 1 to 2 weeks before planting, any black cutworms that had been present probably starve to death. The presence of weeds only a few days before planting increases the likelihood of cutworm damage if larvae are present in the field. Begin watching emerging seedlings carefully for early signs of cutworm feeding (pinholes in the leaves) and for plants that have been cut off by larger larvae. View the black cutworm fact sheet (www.ipm.uiuc.edu/fieldcrops/insects/black_cutworm.pdf) for more information on injury.

Degree-days can be an effective tool to help determine when to start scouting for black cutworm larvae by predicting larval development and when the first cutting of plants may begin. The accumulation of degree-days begins when a significant moth flight occurs (nine moths caught over 2 days). After an intense capture is recorded, we can calculate degree-days to project when cutting of corn plants will occur. Black cutworm larvae are expected to begin feeding on and cutting corn plants with the accumulation of approximately 300 degree-days (base 50°F) after an intense capture. Just as another reminder, if you are monitoring a pheromone trap, you can predict cutting dates in your area by using the Degree-Day Calculator found on the IPM and WARM Web sites.--Kelly Cook

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