There have been reports of true armyworms in wheat this week. The wheat crop is late this year, so some fields may need to be treated for this pest. We do not recommend treating for armyworms in wheat at this time of year unless they are cutting heads or unless the wheat is still in the milk stage. Once the crop reaches the soft dough stage, armyworms do not cause yield loss (unless they are cutting heads). Armyworms tend to hide on the ground under litter during daylight hours and feed on the plant at night. They also feed on the lowest leaves first and work their way up the plant. When scouting, look under clods or dead leaves at the base of plants. Potential yield loss from armyworms depends on the stage of the plant at the time of feeding. Wheat that has reached the soft dough stage (or later) can be completely defoliated with no significant yield loss. This year much of our wheat crop is late and some may still be in the milk stage. Armyworms feeding on the flag leaf prior to soft dough stage can reduce yields. If defoliation is significant in fields prior to soft dough stage, treatments may be warranted. Refer to Insecticide Recommendations for Arkansas (MP144) for a list of currently labeled insecticides. The best time to apply an insecticide would be late afternoon since the armyworm feeds primarily at night.
Another concern with armyworms in wheat is the crop that is adjacent to the wheat. Armyworms will often move out of a wheat crop into the adjacent area after the wheat if defoliated. If rice, grain sorghum or corn in nearby, it could be damaged by migrating armyworms. These insects often move quickly and in large numbers and may cause significant defoliation in the adjacent crop seemingly overnight. We have already had a few reports of armyworms moving into, and damaging seedling grain sorghum next to wheat. Any grain sorghum, corn or rice next to wheat should be watched closely for armyworm damage. Insecticide Recommendations for Arkansas (MP144) has a list of currently labeled and recommended insecticides. As in wheat, the best time to apply insecticides is late afternoon or evening.