Corn – Keeping Out Earworms

Q: Our corn will soon be silking. How do I keep keep earworms out?

A: Earworm caterpillars come from eggs laid by a moth soon after the first appearance of corn silks. Some gardeners try to physically exclude them by placing a clothespin at the point where the silks emerge from the shuck. Others put mineral oil or vegetable oil at the same spot two days after full silk, when the silks are beginning to brown. Timing is important: too-early treatment causes non-pollination at the tips of the ears. Chemical dusts containing carbaryl (Sevin) or permethrin (Eight) give a wider window for treatment.