Western bean cutworm is a corn pest that has become an economic concern in some parts of Iowa in the past decade. Iowa State University led a pheromone trapping network to monitor the presence and timing of emergence of adults in Iowa. The map shows the reported data on moth captures for the season.

ISU Corn and Soybean Initiative partner agronomists were surveyed in December about pest management issues in corn and soybean in the 2006 growing season. Here are summarized results of the survey concerning western bean cutworm, and results involving soybean pests will be presented soon in the ICM newsletter. There were 17 usable responses from 28 companies polled, and responses geographically covered most parts of the state except extreme south-central Iowa.

Both the incidence of western bean cutworm and yield losses from damaged ears varied considerably from field to field and from area to area. Those who estimated losses generally reported 2 to 5 bushels per acre, with one report of losses in a few fields that reached 10 percent. The agronomists were asked how farmers they worked with managed for western bean cutworm, and most reported using the suggested economic threshold of 8 percent of plants with egg masses or newly hatched larvae present; however, two reported that scouting was frustrating to do. It was noted that there were scouted fields that never reached threshold yet suffered apparent economic losses from western bean cutworm damage. Complicating scouting is the difficulty in scouting fields around silking. In addition, one respondent specifically requested information about thresholds for multiple pests (in corn, that could include western bean cutworm and corn rootworm beetle adults, among others).

Rich Pope is an extension program specialist in entomology with responsibilities in integrated pest management and pesticide applicator training.