Pounce 3.2EC and black cutworms: Spray now, spray later, or not at all?

This spring, FMC Corporation is promoting the application of Pounce 3.2EC to preemergent corn as a preventive treatment for black cutworm. This is not a good integrated pest management practice. A list of my concerns and good IPM alternatives follow.

Concern #1. Preventive insect-icide treatments. FMC promotional material suggests applying the insecticide up to 14 days before planting. Using a synthetic insecticide as a preventive treatment cannot be economically or environmentally justified if a rescue treatment can provide equal or better control. Because black cutworm moths are migratory insects that fly from Texas and Mexico, there is no possible way to determine when they will arrive and where they will land in Iowa cornfields. Certainly we cannot know whether the moths will lay eggs in your field. The probability of black cutworm damage is very low in any field, particularly if the field is free of broadleaf weeds in April and early May.

Concern #2. Insecticide guarantees. FMC guarantees that Pounce will control cutworms when applied as a preemergence treatment. Dont be lulled into a false sense of security with this guarantee. The guarantee is subject to the condition that the field must be scouted for insect damage, so spraying early in the season wont preclude the possibility of crop injury by the insects.

Concern #3. Field scouting. FMC suggests, Use Pounce early. Then forget about corn pests that reduce plant stand. They also state, With Pounce, you dont have to worry about checking your fields for stand damage during the busy growing season. These are very misleading statements because for the Pounce guarantee to be valid, you must check the field and use accepted scouting practices.

Concern #4. Additional pests. FMC states that, If you rotate out of sod, hay or alfalfa and youre worried about wireworms, Pounce and a seed protectant (hopper box treatment) are an effective treatment against wireworms and other seed pests, too. This combination is a less expensive treatment than a granular soil insecticide. But, Pounce will not control wireworms, and a seed treatment will not provide protection against that other devastating soil pest, the true white grub. Sod and hay fields converted to corn can have true white grubs, one of the most damaging pest species in seedling corn. True white grubs will feed on the seedling roots and kill the plant; the seed treatment wont provide adequate protection of these roots. Therefore, I recommend applying a granular soil insecticide when planting in fields following sod or hay to control both white grubs and wireworms.

The alternative. There is a better alternative to black cutworm management than buying unnecessary insecticide and increasing on-farm input costs. You can have the fields scouted when first cutting is expected. The IPM program at Iowa State University has black cutworms traps in half of the Iowa counties. When the moths arrive, we predict when cutting will occur and provide that information in this newsletter. Then you can scout the field, look for early signs of injury, determine if the economic threshold has been reached, and apply insecticide if it is really needed.

Pounce 3.2EC is a proven and effective insecticide for controlling black cutworms, especially in rescue treatment situations. However, using it as a preventive treatment in the absence of insects is irresponsible stewardship of an insecticide and goes against the principles of integrated pest management. Use your insecticides wisely.

Updated 04/06/1995 - 1:00pm