Early Season Corn Pests

As we begin to get crops in the ground and start to keep a closer eye on the fields, it is best to keep in mind the early season pests that might present themselves. Scouting fields early in the season is key to ensuring healthy stands, here are a few pests to keep an eye out for that may impact overall stands.

Black Cutworm larvae are common in fields that had annual weed growth, attracting the moths to lay their eggs in those areas. Once hatched, the larvae feed on the corn plant at or below the soil surface, “cutting” the plant and causing them to wilt and die. These larvae feed mostly at night or during overcast days, they can be found near the base of the plant under the soil during the day. To identify Black Cutworm, they can vary in size from 1/8th of an inch up to 2 inches. As they grow, they become darker in color, turning gray/black as they mature with a greasy texture appearing on their skin.

Seedcorn Maggot is a pest that has been a problem in fields with high amounts of organic matter. These pests affect corn seed during cool, wet conditions. Seedcorn Maggots are pale, yellowish maggot that can be found burrowing into the seed. They are much smaller than Black Cutworm, being only ¼ inch in length at full maturity.

Wireworms are like Seedcorn Maggots, feeding on the corn seed and the germ, burrowing their way through the seed. They are common in fields of corn with no insecticide protection, a heavy topic the last few years in New York. Wireworms are hard bodied larvae that are brownish-red in color. Adults can range from ½ inch to 1 ½ inches when fully mature. They favor cooler temperatures, so as the weather begins to warm the soil, the threat of wireworm damage begins to decrease as they retreat further down into the soil.

White Grubs are an occasional pest in corn that stunt the corn plant. They can be found at different life stages and inflict different crop damage, all in the same field. Coming from different beetles, it may be hard to identify which they come from, but the larvae are all C-shaped and white in appearance. The White Grubs can feed on the mesocotyl of the plant, causing the plant to not emerge or to appear wilted and stunted.

Armyworm larvae feed on the leaves of the corn plant, causing the leaf margins to be chewed but leaving the mid-rid of the plant. These larvae are dependent on field management, and weather patterns. Armyworm larvae feed at night and during cloudy days, you can often find them hiding in the whorl of the plant during the day. Damage may be heavy enough to warrant a control method, some plants may recover if the growing point is not damaged. They are brown in color with dark vertical lines. At full maturity, they can be about 1 ½ inches in length.

Cassidy Fletcher, SEEDWAY Northeast Sales Agronomist and Technical Lead