Selecting a Soil Insecticide

Part 2, Section 2: Corn Pest Management

Corn Pest Management

INSECTS

Selecting a Soil Insecticide

In Pennsylvania field corn, the primary reason for using a soil insecticide is to protect the crop from corn rootworm injury. Other pests occur much less frequently and under specific cropping patterns, but controlling these species with a broad spectrum soil insecticide is unlikely to be profitable. When selecting a soil insecticide, you first must know which insects, if any, are likely to attack your crop in the coming year. Field history will be an important part of this decision, but new information from scouting will be vital.  See Table 2.1-6 for field characteristics that increase the likelihood of a corn insect species. Table 2.2-22 shows the spectrum of soil insecticide activity on soil insects. Choose the soil insecticide that controls the pests likely to occur in your field.

Selecting a commercially-applied seed treatment or planter box seed treatment

Rather than a broad spectrum soil insecticide, in some situations a commercially applied seed treatment or planter box seed treatment may be preferred. Unfortunately, many seed companies are not giving growers much of a choice in whether or not they receive a seed treatment because the great majority of field corn seed is available only with a seed-applied insecticide and/or fungicide (See Table 2.2-23 for spectrums of activity for these newer seed treatments against seed-feeding insects.) A seed treatment may be a good choice in first-year corn fields that were in pasture or hay the previous year, or when the soil has naturally high organic-matter content. Under these conditions, seed corn maggot and/or wireworm can cause stand reductions. Several seed treatment products provide control equal to a soil insecticide for these two pests at a much lower cost per acre.

Foliar feeding insects such as black cutworm, true armyworm, stalk borer, sod webworm, flea beetle, and billbugs are best controlled with pre- and postemergent applications of a foliar insecticide.