Yavapai Gardener: April 2010

Are your plants getting the tattered look as in these pictures? Then it may be the creature known as the Army Cutworm. They are the caterpillars, sometimes called grubs, of various moths. Their voracious appetites can decimate a garden and are showing up in Prescott gardens.

Cutworms are found in the debris of the garden where they remain semi-dormant waiting for the right conditions. When temperatures warm they begin to feed. You will likely not see them, they are active at night but the damage they cause will be evident at first light. They cut plants down right at the soil line, sometimes dragging unfinished plants into soil cracks. (Apparently gardeners in Prescott have been seeing a lot of them climbing up the sides of their houses and across driveways.)

Once the cutworms have fed enough, most likely after finding and destroying your favorite plant, they pupate in the soil and emerge as a moth—known as a Miller Moth. Fortunately they have just one generation per year but a single moth can lay a thousand or more eggs.

The moth likes to lay its eggs in dense vegetation so keep weeds down. Rototilling and spring digging can also reduce the populations. A way to thwart their eating sprees is to place a collar around the stem of the plant. The collar can be plastic, aluminum foil or cardboard. For seedlings cut paper towel or toilet paper cores to size and place over the plants. Cutting the bottom out of paper or plastic cups works well also. Push the collar below soil level.

Information taken from http:www.colostate.edu/Depts/CoopExt/4DMG/Pests/cutworm.htm

It may be possible to control cutworms with a beneficial nematode and a Trichgramma wasp. The nematodes target the cutworms themselves, the wasp targets the eggs. There are also pheremone traps for moths. I have never used any of these products so if anyone has information about them, let me know so I can post your results for others to see.