Cutworms

Cutworms in the garden

Cutworms can be a major problem of vegetable gardeners and sometimes flower gardeners in early summer.  The gardener will look at his or her garden in the morning and find plants lying on the ground, cut off cleanly at the base. The plants are not eaten, just left wilting in the morning sun. This is a sign that the garden has cutworms.  Occasionally wilting plants that appear to be in damp soil will show cutworm damage to the stems if they are closely observed.  The cutworms may have only partially severed the stem.

 

Cutworm.  Photo en.wikipedia.com

Cutworms are the larvae stage (caterpillar) of several species of night feeding moths in the family Noctuidae and they can vary in color and markings depending on what species they are.  Cutworms are caterpillars about an inch long, and tan, gray, yellowish or green.  Some have rows of dots or lines on their bodies.  They are most often seen in a curled, “C” position.

Cutworms like to eat the stems of tender seedlings and favor crops like cabbage, tomatoes, corn, beans, and sunflowers but almost any plant can fall victim to the hungry caterpillars when it is young.  Like their parents cutworms feed at night.  (Adult moths don’t harm plants.) They curl around the plant and cut a narrow band of tissue straight across the stem to eat.  Gardeners rarely see them in action, but you may find them when you move debris or mulch around or dig in the garden soil. During the day cutworms remain hidden to avoid being eaten by predators or having the eggs of parasitic wasps laid on them.

In the home garden cutworms are fairly easy to control without using pesticides.  First leave a bare, un-mulched strip of ground about three feet wide between grassy areas and the garden.  Cutworms also feed on the stems of weeds and grasses and can move easily into the garden from lawn areas. Bare ground deters them. Lightly cultivate this area several times a week to expose any cutworms hiding in the soil.  If you see any squish them.  Raised beds also help deter cutworms.  Keep weeds and grass away from the bed walls.

Second, remove mulch and debris from around garden plants until they are older and have tougher stems.  Mulch and debris provide moist hiding places for cutworms during the day.  Lightly cultivate the soil around the plants frequently, removing and killing any cutworms you uncover.

Third- there is an old, very effective trick to deter cutworms when you are putting out transplants like cabbage and tomatoes.  Simply wrap the stem of each transplant with a narrow strip of newspaper at soil level.  The strip need only be 2 inches above the soil line.  You could also cut toilet paper or paper towel cardboard tubes into little round sections and put these collars around each plant.  Or use paper cups with the bottom removed placed over the plant and pushed into the soil.  Anything that stops the cutworm from curling around the plant stem will work. They won’t eat paper. 

You can leave paper and cardboard items in place; they will disintegrate in the weather as the plant grows.  Remove any foil or plastic items you placed around plants though as soon as they have grown a bit- usually just 2 weeks or so after transplanting will do. These may damage plant stems as the plant grows.  A month or so after plants have sprouted or were transplanted it’s usually fine to mulch around the plants.

Diatomaceous earth and things liked crushed eggshells are not effective cutworm deterrents.  Several garden pesticides will work including carbaryl, cyfluthrin, and permethrin but are rarely necessary.  They are best applied in the evening.  Read and follow label directions.

Not every gardener will have cutworm problems.  Cutworm damage varies from year to year and garden to garden.  But if you notice plants cut off and lying on the ground protect the remaining plants. Gardeners who use cover crops that are tilled under in the spring may have more cutworm problems than other gardeners.