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Angie Peltier

Angie Peltier
Former Extension Educator, Commercial Agriculture

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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. 2012 Black cutworm cutting dates (Kelly Estes).

Black cutworm cutting dates estimated

Posted by Angie Peltier - Insects

Kelly Estes, the State Survey Coordinator of the Illinois Cooperative Agricultural Pest Survey, has estimated the 2012 Black cutworm cutting dates for the nine Illinois regions (Figure). Cutting dates, or the dates that larvae are likely to begin damaging corn, are estimated by determining the dates of peak moth flight in the area and degree day accumulation. The BCW cutting dates for the NWIARDC are estimated to begin the week of May 6th.

As stated in a previous Blog posting, high weed populations favor black cutworm infestations. Other factors that favor infestation include delayed planting and tillage operations, conservation tillage, field depressions and fields next to vegetation. Corn is most susceptible when it is less than 15 inches tall. Just like with frost damage, cutting or severe damage below the growing point is fatal to the plant.

Larvae begin feeding on corn after they have destroyed the weeds they had been feeding on. Although initial damage can appear as irregular holes on leaves, the real damage occurs after the larvae reach the 4th instar growth stage. This is when cutting activity begins. Finding the actual larvae at this time grows more difficult as they live in burrows in the soil by day and feed/cut by night.

Estimated cutting dates are important because scouting activities should begin before or around this date. Plan to scout 250 plants in each field once per week after emergence. Look for feeding on leaves or cut plants. In areas with cut plants, dig up larvae around the base of the plant in the soil to determine the larval growth stage. This data, along with the plant growth stage and percentage of cut plants can help you to determine whether to apply a rescue treatment using the Rescue Treatment Calculator. More information about the BCW life cycle, growth staging larvae, scouting, and the Rescue Treatment Calculator can be found on an IPM fact sheet, written by Kelly Estes and colleagues.

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