Many European corn borer control treatments are applied aerially. In areas with a history of European corn borer problems, granules, if available for an approved insecticide, are the preferred formulation, particularly for control during the whorl stage of corn development. Fortunately, most aerial operators are equipped to apply either a granule or a liquid formulation. Although not true of all compounds, efficacy comparisons between granules and liquids of the same compound applied to whorl-stage corn usually favor granules. Granules have additional advantages: (1) no mixing or water is needed, (2) there is less drift, (3) personal hazard is usually less, and (4) there is less hazard to honeybees and other beneficial insects. Granule insecticides also better control larvae during the tasseling and silking stages of corn development. Granules roll down plant leaves easily and tend to concentrate close to larvae feeding in the whorl. However, liquid insecticides provide good control (Table 7) and are appropriate when conditions are unfavorable for granules.

High-clearance equipment, when available, can be modified to apply either granules or liquids. To control leaf feeding, granules must be directed into the plant whorl. To control sheath and collar feeding, granules must be directed over the entire plant and into leaf axils. This can be done by using 7- to 10-inch (18- to 25-cm) spreader banders attached to delivery tubes extending from each insecticide box. Be careful to follow label directions closely, especially to minimize effects on birds and other wildlife.

For liquid applications to reduce leaf feeding, use one or two nozzles per row. Adjust the nozzles to deliver the spray above and into the whorl. To control sheath, collar, and ear feeding, use four nozzles per row and direct the spray at the ear zone. Thorough coverage is important. Ground applications should be applied with a minimum of 10 gallons of water per acre. To control whorl feeding, granule or liquid delivery systems can be mounted on a tool bar and used with cultivation equipment. However, corn usually is too tall and already cultivated when the decision to control whorl feeding is made. Although there are advantages to ground application, equipment availability and time requirements for application to large acreages often force using aerial equipment.

In areas where insecticides commonly are applied at planting or during cultivation to control rootworm larvae, systemic insecticide application has been inconsistent in controlling whorl-feeding European corn borer and is not recommended.

Insecticide application through irrigation water (insectigation), particularly with overhead center pivot irrigation systems, is an effective method and is becoming common in some irrigated areas of the Corn Belt. Because the method is relatively new, technological and environmental tolerances are changing. Before using this application method, consult your local Cooperative Extension Service and regulatory agencies. Some states have very specific rules and regulations regarding the injection of chemicals into irrigation water. One of the primary concerns of insectigation is potential underground water contamination. If insectigation is used, comply with all laws and regulations, including those promulgated by the Environmental Protection Agency, the manufacturer of the insecticide, and local regulatory agencies. At a minimum, make sure the well is equipped with a check valve to eliminate the possibility of reverse flow, or back siphoning, in case the system loses pressure and shuts down during the process. The check valve will minimize the possibility of contamination of the well and underground water.