Issue No. 20, Article 5/August 5, 2005
Don't Forget About Late-Summer Moths in Corn
Seen any moths flying around your porch lights lately? This time of year, lots of flying insects can be found circling lights at night. Among these are a couple that you may not know very well.
One moth we haven't heard a lot about this year is the European corn borer. Our light trap in Champaign caught fewer than 30 European corn borer moths last week. Some were turned up in sweeps of soybeans by Mike Gray in DeKalb this week, and others made their way onto his windshield during the drive back to Champaign. We've also found several floating in water tanks used for holding roots during the root-damage evaluations. Although scouting for second-generation corn borer isn't fun, keep a lookout for any moths flitting around your fields and egg masses on the undersides of the corn leaves. Information on scouting, thresholds, and management of second-generation corn borers can be found in the European Corn Borer factsheet online (http://www.ipm.uiuc.edu/fieldcrops/insects/european_corn_borer/factsheet.html).
Corn earworm flights have increased dramatically over the past week. Darin Kohlmeyer of Syngenta and Dale Brown of Pfister Hybrids have had increased catches in their pheromone traps. In fact, traps are catching between 100 and 200 corn earworm moths each night. Though not a concern in most commercial field corn, the corn earworm can be a severe pest of sweet corn and seed corn. Information on scouting, thresholds, and management of the corn earworm can be found in an online factsheet (http://www.ipm.uiuc.edu/fieldcrops/insects/corn_earworm/index.html).
The last midseason pest of corn to be discussed is new to Illinois. A concentrated effort has been made this summerto monitor for the western bean cutworm with pheromone traps throughout Illinois. To date, the western bean cutworm has been identified in 20 counties. In the July 15 issue of the Bulletin ("Western Bean Cutworm Adults Found in Northwestern Illinois Counties"), Kevin Steffey describes the trapping network as well as details of scouting procedures and management. Iowa State University has a western bean cutworm Web page. If adult moths have been found in your area, scout your cornfields for eggs masses and/or larva feeding on corn plants. Remember, once larvae enter the corn ear, insecticides are ineffective. Scouting and timing of potential insecticide treatments are critical.
As you scout your cornfields, please let us know of any findings. We'll keep you posted of any new information in upcoming issues of the Bulletin.--Kelly Cook