Agronomic Crop Insects – April 27, 2012

Joanne Whalen, Extension IPM Specialist;

Field Corn
As the first plants emerge, we often can see both cutworm and bird damage in the same field. In general, small cutworms feed on leaves before cutting plants. You can distinguish bird damage from cutworm damage by the pattern in the field. Generally longer strips of damaged plants, plants pulled out of the ground, and/or plants cut high that are compressed at the base of the stems, all indicate bird damage. Although birds can cut plants off at the soil surface, they tend to pull plants out of the ground. In addition, if you look closely you will see “bird prints” near the missing plants or holes where birds have pulled plants out of the ground. As a reminder, we did receive a 24(c) Special Local Needs Registration for Avipel Hopper Box (dry) Corn Seed Treatment for bird management on field corn in Delaware a number of weeks ago as reported in WCU 20:3. The 24 (c) label should be on the pesticide canisters. If you need a copy of the label, please contact Dave Pyne at the Delaware Department of Agriculture.

We are starting to get questions about stink bugs in wheat. We can find low levels of native brown stink bug populations (not brown marmorated stink bugs) on heading wheat. At this time, little is known about the impact of stink bugs on wheat in our area. Information from southern states indicates that wheat may be susceptible to native stink bug feeding at the milk and soft dough stages. They also state that it takes extremely high numbers to cause damage to heading wheat. Thresholds in the South for native stink bugs range from one per head to one per 5 to 10 heads. In addition, they find the highest populations of stink bugs along field edges. We plan to gather more information in the Mid-Atlantic region this year on both native and brown marmorated stink bugs in small grains.