Corn earworms are an economic concern in fresh market and processing sweet corn, and hybrid dent seed corn. Please refer to UWEX Publication A3655 The Corn Earworm (attached) by Karen Delahaut and John Wedberg for identification, life cycle, corn ear damage, scouting and integrated pest management control options. A link to the fact sheet is available at http://learningstore.uwex.edu/pdf/A3655.pdf

 

Here are two excellent ways for you to monitor corn earworm flights on a real time basis for your area. 

 

First, the Wisconsin Pest Bulletin published online each week by the WI DATCP pest survey can be accessed at http://pestbulletin.wi.gov/. On the lower right of the bulletin link follow the Corn Earworm link to view CEW pheromone trap captures from around Wisconsin. Once pheromone trap captures of 5 to 10 moths per night are reached for three consecutive nights during silking and before brown silk stage - moths are likely laying enough eggs to warrant treatment for CEW. The best management practice is to maintain a corn earworm pheromone trap on each field or farm near sweet corn or seed corn fields. In the event that you do not maintain your own trap, the Wisconsin Pest Bulletin Corn Earworm link is an excellent guide to monitor CEW moth flight activity in your area. To add precision to your field treatment decision, scout corn fields and check silks for the presence of small, spherical CEW eggs before beginning an insecticide spray program.

 

As of Thursday evening August 9th CEW moth flights remain relatively low, although average CEW moth captures increased over last week. Clarissa Hammond, WI DATCP Pest Survey and one of the Wisconsin Pest Bulletin authors reports the following averages per day for the week ending August 10^th: Lancaster (1.57), Oregon/Stoughton (7.22), Cottage Grove (5.67), North Sun Prarie (4.89), Northeast Sun Prarie (3.67) Janesville (0), Coles Valley (0), Chippewa Falls (1.13), Coon Valley (0.86), Marshfield (4.29), Manitowoc (0.57). Please visit the WI DATCP Wisconsin Pest Bulletin for additional location updates which will be posted into Friday morning August 10th after the UW Extension Wisconsin Crop Manager newsletter goes online.

A second resource for monitoring CEW flights into Wisconsin and the upper Midwest is the Insect Migration Risk Forecast (IMRF). IMRF is predicting a LOW (10-15%) risk of CEW insect migration into Wisconsin for the next 3 to 5 days (through August 14). The potential exists for a sizeable flight of corn earworm moths to arrive in the near future. As weather conditions can change rapidly, and shifting weather fronts alter the CEW migration risk forecast, it is advisable that you frequently view the complete weather/CEW insect migration risk forecast, and receive real time updates. Visit http://agweather.niu.edu/IMRFForecast.html.