A wet spring and late planting could lead to additional pest challenges early in the growing season. Growers should begin scouting for insects early and take measures to protect their crops, say insect control experts from Pioneer Hi-Bred, a DuPont business.
Begin monitoring fields as soon as the crop emerges, says Paula Davis, Pioneer senior manager for insect and disease traits. Scouting for armyworms, black cutworms, white grubs, and wireworms is vital since they typically can surface in early growing stages of the corn crop.
This is a critical period during the growing season," says Davis. "Growers need to monitor their corn crop, looking at specific indicators, then follow a management plan to resolve any issues.
• This year, high flights of armyworm moths have been reported in Tennessee, Kentucky, and southern parts of Ohio, Illinois, and Indiana. Moths prefer to lay eggs in grassy areas. No-till fields, small grains, and pastures are considered high-pressure locations for monitoring. Small armyworms may stay and feed on grassy foliage, but as the pests grow, larger armyworms have the ability to migrate and may pose a threat to nearby or adjacent cornfields, especially no-till fields..
If growers notice chewing of leaves and multiple larvae per plant, use an insecticide treatment. Recommendations may vary for each state, but generally, if 50 percent to 75 percent of the plants have signs of armyworm feeding, further action should be considered.
• Wireworms tend to thrive in extended periods of cool, wet conditions. The main indicator of wireworm is stand reduction. The good news is that many growers already have protection in place through insecticide seed treatment. However, if there is heavy infestation, consider an insecticide or high-rate insecticide seed treatment next year.
• Small black cutworms will show small shot holes in corn leaves. Once black cutworms reach the fourth instar, approximately one-half inch long, they can cut the plant, resulting in stand loss or irregular stands. Corn hybrids with Herculex I technology have very good protection against black cutworms.
The suggested threshold for considering an insecticide treatment has lowered recently due to the high corn commodity prices. Consider using an insecticide treatment if 1 percent to 2 percent of plants are cut and larvae are present.
• White grubs feed on roots of seedlings. In problem areas, growers will see irregular stands since pruning takes place on the roots. While there isn’t much to remedy a heavily infested field, growers can develop a plan for the following growing season — looking at soil insecticide or investing in a higher rate of seed treatments.