Growers Should Scout Corn, Soybean Fields Early to Avoid Pests, Diseases

Main decision to make early is whether or not to replant.

Published on: May 26, 2011

Growers across the United States are concerned about the potential for early-season pests and diseases in corn and soybean crops because of weather conditions so far this spring. Pioneer Hi-Bred experts say corn crops planted early could experience more problems than those planted later because of cooler and wetter soils. Pioneer suggests growers scout their fields and evaluate stand establishment.

Crops planted early in April could experience seed rot or damping off, which occurs when fungal pathogens like Fusarium, Pythium and Rhizoctonia are present in the soil and seedbed conditions are challenging. Concerns of these issues may lessen in areas with delayed planting because of warmer temperatures and drier conditions. However, for growers who plant into late May - experts say those fields could be more susceptible to black cutworm, which grows larger with time increasing the chance of cutting down newly emerged plants. When the cutworm gets to be half-an-inch long it can kill the plant because it leaves small shot holes in corn leaves, resulting in stand loss or irregular stands.

Growers also should scout for soybean diseases, such as Pythium, Phytophthora and Rhizoctonia. Experts say tracking emergence is important.

Iowa State University plant pathologist Alison Robertson says if you are wary of disease, take note of your growing conditions since planting; make sure you get out in the field and scout closely to see if you've got disease pressure. And, if you do, be ready to replant.

"Look for yellow, grayish-green leaves. Dig seedlings up to inspect roots. With corn, the mesocotyl could be rotted, and seed roots could be rotted," Robertson said. "In soybeans, you could see rotting in the taproot. But, you won't see any of it until you dig those plants up. Do stand counts and decide if a replant is needed. You can use seed treatments and change hybrids, but the only thing to really decide is to replant or not."