This spring, FMC and Zeneca are promoting the use of two of their insecticides, Pounce 3.2EC and Warrior 1EC, as preplant treatments to prevent black cutworm injury to corn. This is not a good integrated pest management practice. Here are my concerns and an alternative from an integrated pest management perspective.

Concern #1: Preventive insecticide treatments. The Pounce label states that the insecticide can be applied up to 14 days before planting; the Warrior label only states that it can be applied before planting. The basic principles of integrated pest management ask:

• Can the insect be scouted?
• Can the economic damage be predicted based upon field scouting?
• Can a rescue insecticide be applied?
• Can the rescue treatment provide equal or better control than the preventive treatment?

The answer to all four questions is yes. The use of an insecticide applied as a preventive treatment cannot be economically or environmentally justified when a rescue treatment can provide equal or better control.

Concern #2: Black cutworm migration. Black cutworm moths are migratory insects that fly to the Midwest from Texas and Mexico. We have pheromone traps that determine when they arrive, but the traps do not tell us where they laid their eggs, how many eggs they laid, what the cutting potential is, or even if moths stay within the county where they are trapped. In fact, the moths may pick up the next night and continue their migration to Illinois or Wisconsin. It cannot be predicted with certainty that these moths will lay eggs in your field, either.

Our trap catches last year allowed us to predict that black cutworm cutting would begin between May 18 (southeast Iowa) and May 25 (northern Iowa). The first cutting was reported in eastern Iowa on May 22. This first cutting date was about five weeks after the first corn was planted. In an advertisement for a different insecticide, FMC states: In corn farming, as in warfare, its best not to fire at the enemy six weeks before they arrive. This logic certainly should be applied with black cutworms and preplant preventive treatments.

Concern #3: Potential for cutting. The last time a serious cutworm outbreak occurred in Iowa was 1984. Recent history strongly suggests that the threat of black cutworm damage on a large scale is overrated. The probability of black cutworm damage is very low in any field, particularly if the field is free of broadleaf weeds during April and early May.

Concern #4: Insecticide cost. These insecticides are not cheap. For the low- and high-end label rates, cost will be about $5.40 (4 oz.) $11.30 (8 oz.) per acre for Pounce and $4.68 (1.92 oz.) $8.10 (3.2 oz.) per acre for Warrior. Costs will vary from dealer to dealer.

Concern #5: Insecticide guarantees. FMC guarantees that Pounce will provide control of cutworms when applied as a preemergence treatment. Likewise, Zeneca says that with one preplant application for cutworms, you have one less problem to worry about. Do not be lulled into a false sense of security with insecticide guarantees or claims. Any guarantee or claim is subject to the condition that the field must be scouted for insect damage. Just because the field was sprayed early in the season doesnt preclude the possibility of crop injury by the insects later in the season.

The alternative. There is a better alternative to black cutworm management for the farmer than buying unnecessary insecticide and increasing on-farm input costs. This alternative is to have the fields scouted when first cutting is expected. The IPM program at Iowa State University has black cutworm traps in 75 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, and determine if the economic threshold has been reached. Then the insecticide can be applied if it is really needed.

Finally, let me add that Pounce 3.2EC is a proven and effective insecticide for controlling black cutworms, especially in rescue treatment situations. Warrior is a relatively new insecticide and its performance against black cutworms has yet to be widely evaluated. However, the use of either insecticide as a preventive treatment in the absence of insects is irresponsible stewardship of an insecticide and goes against the principles of integrated pest management. Always use insecticides wisely.

Remember, the black cutworm moth may not lay eggs in your field.