If small insects have been eating holes in your collard greens (Brassica oleracea var. acephala), they’re most likely flea beetles, cabbageworms or cabbage loopers. Flea beetles only reach 1/16-inch long, and they vary in color from tan to black. Cabbageworm larvae are green, reaching a maximum size of 1 1/2 inches long. Cabbage looper larvae are green with white stripes, and also reach up to 1 1/2 inches long when fully grown. All of these insects feed on the leaves of collards, but you can control them without the need for harmful pesticides. Collard greens are often grown as annuals, but overwinter in U.S. Department of Agriculture plant hardiness zones 8 through 12.
Combine five parts water, two parts isopropyl alcohol and 1 teaspoon of dish liquid in a spray bottle. Spray the collard greens thoroughly, contacting all parts of the leaves once a week, to control flea beetles.
Mix Bacillus thuringiensis concentrate with 1 gallon of water in a hose-end or pressure sprayer. Use 2 to 4 teaspoons per gallon for cabbage loopers and 1 to 3 teaspoons per gallon for cabbageworms.
Spray the collard greens thoroughly, covering all parts of the leaves, until the plant is evenly coated but not creating runoff. Repeat this once a week. It’s most effective when applied while the cabbageworms or loopers are still in early stages of development.
Things You Will Need
- Isopropyl alcohol
- Dish liquid
- Spray bottle
- Bacillus thuringiensis (Bt) concentrate
- Hose-end or pressure sprayer
- Reapply either of these insecticides after periods of rain.
- Wear gloves when applying Bt.
- Wash your hands after applying any insecticides.
- Keep children and pets out of the area until the spray has dried.