Editor's note: High-resolution digital files are available to use with this story at http://www.aces.uiuc.edu/news/News_Photos/weeds
Professor of entomology and crop sciences Extension coordinator Mike Gray urges producers to look for early signs of leaf-feeding injury from black cutworm larvae. The migratory moths, which lay eggs on winter annual weeds in producers' fields, have been captured in pheromone traps throughout much of Illinois. Following hatch from the eggs, the larvae begin to feed on weeds, but they eventually have the potential to cut seedling corn plants.
Record-breaking warm temperatures in March persisted into early April, and as a consequence many fields across southern and central Illinois have been planted and are beginning to emerge. Corn in the one- to four-leaf stage of development is most susceptible to cutting by black cutworm larvae.
"Even if you planted a Bt hybrid, don't be lulled into complacency," said Gray. Under heavy infestations, control afforded by some Bt hybrids may be inadequate. University of Illinois Extension personnel Dale Baird (Lee County) and John Fulton (Logan, Menard, and Sangamon) reported captures of nine or more moths over a one- to two-day period on March 24 and March 30. Retired crop systems Extension educator Jim Morrison reported that 16 moths were caught on April 2, the earliest and most significant capture in many years.
Fields most at risk from black cutworm injury include those heavily infested with winter annual weeds. Favorite targets for egg-laying black cutworm moths include mouse-eared chickweed, bitter cress, shepherd's purse, yellow rocket, and pepper grass. More information about the biology, life history, and scouting procedures for the black cutworm is available at: http://extension.cropsci.illinois.edu/content/black-cutworm.
Gray encourages readers to visit the following North Central IPM PIPE website (http://apps.csi.iastate.edu/pipe/?c=entry) to view captures of black cutworm moths. According to Kelly Estes, State Survey Coordinator, Illinois Natural History Survey, trapping for other insect pests -- the European corn borer, corn earworm, western bean cutworm, and fall armyworm -- will also be reported on this site throughout the summer.