Assassin from below: Cutworms

May 06, 2015

by Dale Odorizzi, Master Gardener of Lanark County

Have you ever gone out in the morning to admire the Beefsteak or Roma tomato plants that you planted the day before only to find one, two or more plants cut off at the soil line and lying flat on the ground?

If so, your plants were visited overnight by cutworms! In my garden, my pepper or tomato plants are the usual victims of these predators. I have not had a problem with flowers seedlings.

Cutworms are the larvae of the family Noctuidae which is a large family of brown or gray moths. The larvae are fat, greasy-looking gray or dull brown and are 2.5-5 cm in length. At night, these caterpillars feed on stems of seedlings, especially transplants, near the soil line, severing the transplants or eating the small seedlings.

During the day, they rest below the soil surface, curled by the plant stems. If you do find a transplant laying on the ground, dig around the plant and you just might find a cutworm to squish.

While you can apply parasitic nematodes to your soil to get rid of cutworms, I have found the simplest and most cost-effective method for controlling cutworms is to put something between the transplant stem and the soil. There are a number of barriers you can use and I have tried most of them.

My first attempt was to wrap tinfoil loosely around each transplant stem, ensuring that the tinfoil was 2.5 cm above and below the soil line. This worked really well at preventing cutworm damage but at the end of the year, my tomato plants had tinfoil around them or my garden had tinfoil in it. Try again.

Next try, I created a collar made from toilet paper rolls. Again this prevented the damage but in the process of situating the collar at the right level, I frequently sliced the tomato plant stem, doing as much damage as a cutworm.

Not to be discouraged, further research suggested inserting a finishing nail close to the stem of each plant. I envisioned having a garden full of nails and decided to try wooden toothpicks instead. I put one on each side of the stem, as close as I can get, maybe not quite touching but almost.

The toothpicks worked great. They kept the cutworms away from the plants, were quick and easy to push into the soil, close to the stem (half above and half below the soil line) and best of all, they decomposed in the garden with no need to find them at clean up time.

From - The Edible Garden Newsletter, published monthly by Lanark County Master Gardeners and available on their website ww.lanarkmg.blogspot.com. 

Enjoy The Edible Garden Newsletter published monthly by Lanark County Master Gardeners and available on our website www.lanarkmg.blogspot.com or follow us on Facebook or Twitter @lanarkmg.