Plants can stand a considerable amount of whorlworm damage. When worms infest young plants shorter than 24 inches high, the center of the plant may be killed. Economic Threshold Control of fall armyworm and other whorlworm infestations is critical on young plants less than 15 inches high and on plants approaching heading. Between these two stages, the plant can withstand considerable defoliation or leaf loss. Ground application, using 20 gallons of water per acre, has given the best results.
Control is needed when an infestation averages one worm or more per plant.
Directed sprays over the whorl are essential for effective control. Economic losses probably do not occur unless populations reach or exceed one larva per plant. Damage Eggs are laid by moths at the base of seedlings. Larvae form silken tunnels covered with soil particles, and these are attached to the base of plants. The larva burrows into the stalk.