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Ag Matters Column: Cutworms in the vegetable garden

If cool wet weather encourages cutworms in gardens, we may have a bumper crop this year.

Cutworms feed on many of the vegetables grown in the home garden with damage to beans, cabbages and other cole crops, corn, peppers, potatoes, eggplant and tomatoes being most common.

Although there are several species of cutworms that occur in Minnesota, the damage is similar; the young plants are cut off at or just above the soil line. There are also a few species of climbing cutworms that move up the plants and feed on foliage, buds and fruit.

Cutworms are the caterpillars of gray or brown colored night flying moths. The moths of some species migrate into the state from the south and lay eggs on the soil. Other cutworm species are native to Minnesota and over-winter as eggs and pupae. They emerge early in the spring and begin laying eggs on small weeds and debris.

Cutworm populations are affected by weather, particularly rainfall, and numbers can vary from year to year.

The cutworm larvae feed primarily at night, but may be active during the day, particularly when it is cloudy. To monitor for cutworms, check the plants in the morning when the damage is fresh and easier to see. Look for plants that are cut off or damaged within about an inch of the ground. The cutworm that caused the damage can often be found under soil clumps or within the upper inch of the soil near the plant that was cut off.

Cutworm control is most effective when the caterpillars are small. Begin by keeping garden free of weeds and debris before and after the vegetables are planted. This will remove egg-laying sites and a food source for the small cutworms. Removing debris and tilling the garden in the fall will help eliminate over-wintering larvae.

Cutworm damage to transplants can be controlled by placing a physical barrier around the plant at planting time. Protective collars made of aluminum foil, strips of paper grocery bags, cardboard cylinders or tin cans will protect the plant. It is important that the collars are placed so that they protect the plant several inches below as well as above the soil.

If populations are very high, or if the number of transplants makes it too labor intensive to use protective collars, a residual insecticide can be effective against cutworms. Carbaryl (Sevin), cyfluthrin and permethrin are insecticides that will be effective when applied to the stems of the plants. For the best results, apply the insecticides in the evening.

Read and follow all label instructions and precautions carefully. Be sure that the plant, or group of plants, you wish to treat are listed on the label.

For more information, contact me at the Polk County Extension office in McIntosh or at the Clearwater County Extension office on Wednesdays. Our toll free number is 800-450-2465. If e-mail is your thing, contact me at Source: Carl Hoffman, Stearns County Extension Service.