Cutworms

Other Information:

There are a number of species of cutworms which are variable in color. All have a hardened shield on top of the body behind the head.  Cutworms are active just under the soil surface and will curl into a ball if disturbed (not to be confused with white grubs, or Japanese beetle grubs, which are C-shaped). Cutworms can attack seedling plants by girdling or cutting through young stems. Some cutworms, such as the dingy cutworm, also prefer to lay eggs in soybean fields, and can contribute to high populations in corn if it follows in the rotation.

Seedcorn Maggots

Other Information:

The larvae are typical maggots, less than 1/4 inch long, legless and cylindrical, tapering to a point at the head, dirty-white to creamy-yellow in color. Seedcorn maggots feed underground on cotyledons and can also burrow into seeds. Damage from this insect is accentuated when cool, wet weather delays sprouting and emergence. The adult flies, similar to house flies, are attracted to decaying organic matter.

White Grubs

Other Information:

White grubs are white to cream-colored C-shaped grubs (1/4 inch to 1 1/4 inches long) that feed on the fibrous roots of soybeans.  The predominant grubs in Minnesota have a long life cycle of generally 3 years. They attack soybeans following sod throughout the state.  In western Minnesota one species may attack soybeans in sandy soil near cottonwoods, poplars, or willows.  Their root pruning can lead to stunting and death of plants. No rescue treatments are available and soil insecticides are labeled for white grubs in soybeans. If a problem is anticipated, or if abundant grubs are detected at tillage, consider planting corn with a soil insecticide

Wireworms

Other Information:

Wireworms are rarely a problem for soybeans, but they can attack germinating seeds and the soft, underground part of the stem.  Damage has been reported when soybeans follow sod, such as pasture or Conservation Research Program (CRP) land that was reclaimed for crop production.  Low-lying areas of fields already in production can also experience problems, particularly if weather after planting is cool and wet enough to delay germination. Seed treatments are typically recommended in these higher-risk situations.