During the first week of July, Alabama Extension entomologists received reports of fall armyworm outbreaks in pastures and forages across central and south Alabama. Typically, fall armyworms cause the most damage in the late summer or early fall when populations are greatest. The drought-like conditions many fields are experiencing across the state are favorable for fall armyworm outbreaks.

Fall armyworms have a wide range of host plants including forage grasses, corn, alfalfa, peanuts, soybeans, and most vegetable crops. Damage is mainly caused by older caterpillars and can vary according to the type of grass and management practices. In closely grazed fields, grass may appear thin with brown spots, resembling drought stress. In hayfields or pastures, most of the tender green foliage is removed.

Fall Armyworm Management

When treating fall armyworms, smaller worms (<1 inch) are easier to kill than larger worms. Treatment is recommended when an average of two to three or more worms are found per square foot. There are several insecticides labeled for fall armyworm control that can be found in the Alabama Pasture and Forage Crop IPM Guide.

Pay attention to application timings and the grazing intervals for livestock. If damaging levels are found in fields that are almost ready to mow for hay, consider mowing earlier than normal.