Intense flights of black cutworm moths were reported in widely scattered areas throughout Illinois April 23-26. An intense flight is defined as the capture in a pheromone trap of 9 or more moths over 1 to 2 days. From this date (biofix), we can begin to accumulate heat units (base 50 ºF); when approximately 300 units have been reached, cutting of seedling corn plants may begin. Seedlings at or below the 4-leaf stage of development are at greatest risk.

Intense flights during this active 4-day period were reported by the following extension educators: Dale Baird, Lee County; Greg Clark, Whiteside County; Doug Gucker, Piatt County; Doug Jones, Franklin County; Mike Roegge, Adams County. Mike Vose, farm foreman at the Orr Research Center in Pike County, also reported an intense flight during this time frame.

Using the insect degree-day calculator, producers should be alert to the potential for cutting of plants in areas near Franklin County by May 18. Cutting of corn plants in central and western Illinois could begin by May 23, and in northern Illinois during the last week of May.

These projections are based on only those intense flights that have been reported by our cooperators. Producers should be vigilant with scouting because cutting of plants could occur before these projected dates if there were intense flights that happened but were not reported. Fields with high weed densities this spring that were tilled and planted late compared with adjacent fields are at most risk for black cutworm injury. For more information about the black cutworm (biology, life cycle, scouting procedures, economic thresholds), visit ipm.illinois.edu/fieldcrops/insects/black_cutworm.pdf.

SOURCE: University of Illinois.