Wildlife Food Plots and Hayfields Beware

Last week Extension’s news article talked about army worms in home lawns. These little larva have spread to many of our hayfields and pastures eating the lust green leaves and leaving only stems. If you have not checked your hayfield or pasture, it would be a good thing to do so now. As you inspect your fields, look closely to see if there are areas of the field that are lighter in color or show signs of lack of water. Growers that use good management practices for any of these crops will probably be more susceptible to damage since the army worm moth selects fields with high quality forage to lay eggs.

The latest damage I discovered was in a wildlife food plot of brown top millet with mature seed heads. It is the time of the year for hunters to plant fall food plots so be diligent in scouting for army worms in these newly established fields. These young plants will be very susceptible to this pest. Not much can be done to prevent an outbreak other than delaying planting until the middle to late October. The key to control is scouting and rapid response.

The fall armyworm is a chronic pest in the Southeast. The caterpillars feed on a variety of forage crops, but seem to prefer lush, green, well-fertilized bermudagrass. Other forage grasses which are common hosts for fall armyworm are bahiagrass, pearl millet, sorghum-sudan hybrids, tall fescue, and various winter annuals, including ryegrass, rye, wheat, and oats. More than 60 plants have been reported as hosts of the fall armyworm, including corn, alfalfa, cotton, soybeans, and most vegetable crops.

The last major outbreak was in 2002 although there are some producers that have some damage almost every year. We believe that the drought this summer has contributed to the high numbers this year. Fall armyworms are susceptible to cold weather, and are unable to survive even the mildest winters in Alabama. Each year, fall armyworm moths, carried by air currents, make their way from Central and South America. The size and timing of the initial moth flights are two more factors that influence the outbreak potential of this pest.

The adult of the fall armyworm is an ash-gray moth with a wing-span of about one and one-half inches. The front wings are mottled and have white or light gray spots near the tips. The back wings are white with a narrow, smoky-brown edge. Moths become active at twilight and feed on nectar. They have an average life span of two to three weeks.

Fall armyworm damage is most likely to occur from August through October when populations are at seasonal highs. As with other pests, timing is important. If infestations are detected too late, the damage may already have been done.

The decision to treat for fall armyworms depends on the stage of the caterpillars and the intended use of the forage. A population of three or more fall armyworms per square foot is a reasonable treatment threshold. The tiny, light-colored, black-headed larva stage and the light green to almost black mature larva stage can be controlled with the insecticide Sevin. As a general rule, small fall armyworms are much easier to kill than larger ones. If you check an area properly, you can determine the extent of an infestation, and possibly just spot-treat. Harvesting the crop is also an option, which in most cases will cause the larva to go into the ground. Frequently, mowing is the best option for salvaging a hay crop. When this approach is taken, it may be possible to avoid using an insecticide. For landowners with food plots, control or replanting are about the only options available.

For more information, contact the Tallapoosa County Extension Office at 256-825-1050