Black cutworms are now doing their damage. Rich Pope received a report of 5-25 percent cut plants in some Washington County fields. Jim Lafrenz, Pioneer sales agronomist, also reports a field with 16 percent cut plants in Scott County. Carroll Olsen, ISU Extension crop specialist, reports a field in Adams County with 85 percent cut plants, whereas Mark Carlton, ISU Extension crop specialist, reports a field in Marion County with a plant population reduced to 4,000 because of black cutworms. Also, there are numerous reports of dingy cutworms occurring in fields, particularly in southwestern Iowa, but they are not cutting plants.
|Black cutworm cutting young corn.|
These reports highlight the situation that if corn has emerged, it should be scouted closely for leaf feeding and cutting. Cutting could occur across the state with the first cutting for northern Iowa expected on May 15-16 in those fields with newly emerged plants. Fields should be scouted even if a preventative insecticide was applied at planting for cutworms. Additionally, if you find cutworms in the field, confirm whether they have the potential to cut plants (black cutworms) or will mostly feed on the leaves (dingy cutworms). See the May 7, 2001, ICM newsletter article , page 60, for photographs of both cutworms.
This article originally appeared on pages 82-83 of the IC-486(10) -- May 21, 2001 issue.