Producing a successful crop is challenging enough without the threat of yield-robbing pests.

Whether it’s an insect pest that has been encountered for years or the threat of something new, growers should scout their fields early and often to ensure their crop is protected.

Black cutworm

Black cutworms are important for growers to keep on the radar this season. Growers should scout fields for black cutworm at least once per week for three to four weeks after the crop emerges. Feeding may be present above and below the soil surface. Look for areas where plants have not emerged, plants that have been clipped off and are lying beside their stump, or plants that have died within the row. Sometimes they may have been clipped below the soil surface.

Black cutworm migrates in spring, laying eggs on winter annuals. Total feeding time for the larvae ranges from 20 to 31 days and those in the fourth- to fifth-instar stage cause the most damage.

A seed-applied insecticide can help control infestations; however, hybrids with the HERCULEX® I Insect Protection or HERCULEX XTRA Insect Protection trait might be a more effective solution for controlling cutworms.

Corn rootworm

Corn rootworm larvae can cause significant damage by feeding on plant roots, leaving plants vulnerable to lodging during storms with heavy rains and high winds. Growers should be diligent in checking for root feeding and identify common signs of corn rootworm, including brown scars on the root surface, tunnels within the roots and various degrees of root pruning.

Western corn rootworm beetle variant has adapted to rotational practices by laying eggs in soybean fields instead of the traditional cornfields. It has become a serious problem in the Midwest.

Northern rootworm beetle lays eggs in cornfields, but the eggs lie dormant for one year and hatch the second year. Both beetles have caused economical losses in first-year corn. If there have been high thresholds of corn rootworm in a field in the past, planting hybrids with a Bt trait would be the economical solution for pest protection.

European corn borer

When scouting the cornfields, growers should look for egg masses of 15 to 35 eggs on the underside of leaves, usually near midrib. The eggs are laid in an overlapping pattern. Larvae are cream-colored and range in length from 0.04 to 1.18 inches long, depending upon maturity.

More mature plants are susceptible to corn borer injury and early planted corn is most susceptible to larval feeding by the first generation of borers.

Resources

Growers who need assistance in identifying a pest or in determining a treatment threshold should consult their local agronomist or university. These local advisers are familiar with insects of particular concern in a local area and will be able to help devise an effective control plan.

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