Cutworms are the larval stage of several nighttime flying moths. The cutworms will chew through young plants at ground level and destroy the plant. Maturing tomato plants can also be affected by cutworm. The caterpillar will eat irregular holes through the green and ripening tomato fruit. In some cases, ridding the garden of cutworms may require basic maintenance. In heavy infestations, the remedy may have to be a chemical one. With some persistence, you can rid the garden and tomato plants of cutworms.
Cultivate the soil with a tiller several times prior to planting the garden with tomatoes. Exposing the soil will aid in reducing the number of eggs that have already been laid by the night-flying moths. Tilling will also reduce the amount of plant residue that can harbor the larvae.
Clean the area with a leaf rake. Remove all excess weeds and loose plant material. Start a composting pile away from the garden, preferably in an area where no garden plants are tended. Keeping the compost pile away from any garden plants will reduce any contamination from disease and insects.
Inspect the plants and the soil throughout the growing season. Pick the cutworms from the tomato plants as you find them. Check the garden and tomato plants at least once a day for any other insect pests. In most cases, hand-picking cutworms and other pests from the plants can eliminate the need for using a chemical approach.
Apply the recommended insecticide, carbaryl or permethrin, according to the manufacturers labeling. Be sure to cover the ground around the tomato plant as well as the leaves. Some insecticides may last up to one month per single treatment. Others may only reside and be effective for 10 to 14 days. Consult the label for residual times.