Methods to Control Cutworms in a Vegetable Garden

Fowl in the garden are excellent natural cutworm eliminators.

The larvae of several types of large moths in the family Noctuidae, cutworms live in the soil and emerge at night to feed upon the stems and shoots of plants. These fat caterpillars will feed on an extensive list of plants. There are many varieties of cutworm but the most prevalent are the bronzed, black, variegated, dingy, glassy and army cutworms. Cutworms curl into a C shape when disturbed.

Cultural Control

Cutworm incidence can be limited by tilling the garden in the fall. Cutworms will overwinter in soil and tilling in fall exposes them to cool temperatures, which can kill them. Keep weeds and incidental small plants away from the plants you are trying to protect. The cutworm larvae will hide in any organic debris until nighttime. Rake the bed clear of hiding places. If it is safe to do so without harming your plants, flood the area to bring the cutworms up out of the soil. This exposes them to sun and predators.

Mechanical Control

Get a good flashlight and go cutworm hunting at night. Rarely a widespread problem, cutworms will usually cause localized damaged. Learn to recognize the signs. Severed plants, partially eaten plants and waste around the base of plants indicate a cutworm population. Small diameter stems are most susceptible to cutworms as they wrap around the base while feeding. Use a small spade to dig around seedlings and small plants to unearth the larvae. Destroy any you find.

Barrier Control

Many common, nearly free items make effective barriers against the pests. Toilet paper cardboard can be cut to fit around tender stems. Aluminum foil fashioned into a collar will prevent cutworms from getting onto plants. Erecting any barrier around tender plants will help repel cutworms, which aren't climbers. A ring of Popsicle sticks, a slit straw or even newspaper can be used to cover the stems. Diatomaceous earth can damage a cutworm's tender underbelly and may deter the pests if sprinkled in a ring around susceptible plants.

Insecticides

Chemicals have limited effectiveness and should only be used in dire situations. Organic dusts can be sprinkled around the plants. Contact insecticides, such carbaryl, cyfluthrin and permethrin, can be effective but you need to treat the stems and soil in the evening and reapply during the growing season. Spinosad, a natural insecticide made from soil microbes and bacteria, offers an alternative to chemicals and has been approved for use on crops.

References

• University of California Integrated Pest-Management Program: Grape Cutworms
• Veggie Gardener; Tips for Preventing Cutworms; Tee Riddle
• National Sustainable Agriculture Information Service: How Can I Organically Control Cutworms?
• University of Minnesota Extension; Cutworms in Home Gardens; Jeffrey Hahn, et al.; 2011