In surrounding counties, there have been sightings of fall armyworms!
Have you seen any in your lawn or pasture?
Fall armyworms, as their name implies, are most common in late summer and early fall. The moths often migrate in large numbers and lay their egg masses in turf and pasture grasses, as well as in certain field crops.
They are very fond of Bermuda grass, especially when it has been well-fertilized and watered. Newly established Bermuda grass lawns are especially susceptible to fall armyworm attacks.
These caterpillars feed day and night and can cause severe defoliation. Like most caterpillars, they eat very little when small but consume very large amounts of leaf area during the last few days of their larval stage. This is why grass often appears to have been defoliated “overnight.”
Fortunately, turf grasses can tolerate repeated foliage loss, such as mowing, without suffering serious long-term injury. With pastures and hay fields, you need to be more cautious because you do not want to lose too much forage.
So, what are some signs you should look for? They begin by feeding on the underside of the leaf but leave the clear upper epidermis intact. This creates tiny “windowpanes” in the grass blades that appear silver or white. When large numbers of small larvae are just beginning to damage a field or lawn, the grass often has a subtle “frosted” appearance because of these windowpanes.
This is easier to see on the wide leaf blades of barnyard grass, which is a favorite food of fall armyworms.
Scout for fall armyworms by vigorously ruffling the grass with your fingers and carefully counting the larvae that have fallen to the ground in a 1-square-foot area. Do this at several locations in the field or lawn and average your results. Treatment is recommended when counts exceed three caterpillars that are one-fourth inch or longer per square foot so as to not lose cuttings of hay or forage for animals.
The following insecticides are recommended for home loans:
» Bifenthrin (0.115% granules), sold under the brand name Ortho Bug-B-Gone Insect Killer Granules. Apply at the rate of 2 to 4 pounds per 1,000 square feet and water thoroughly after application.
» Gamma-cyhalothrin (0.05% granules), sold under the brand name Triazicide Insect Killer Granules. Apply at the rate of 0.8 pounds per 1,000 square feet and water lightly after application.
» Trichorfon (9.3% granules), sold under the brand name Bayer 24-Hour Grub Killer Plus. Apply at the rate of 2 pounds per 1,000 square feet and irrigate within 24 hours of treatment.
