Managing Garden Pests Organically; Imported Cabbage Worm

Brassica seedlings you are growing now to overwinter, such as kale, cauliflower and broccoli, generally have fewer problems than spring-planted crops. However, they still might be visited by a common pest like the imported cabbage worm, also known as the cabbage butterfly or simply, the cabbage moth.

You can take steps to address a pest like this organically, with a few simple approaches.

• Know thy pest. The imported cabbage worm moth is white or cream-colored, with 1-4 spots on its wings. It has an irregular flight pattern. It lays pinhead-sized eggs on the undersides of brassica leaves. The eggs are cream or yellow-orange. The resulting caterpillar is green with white markings (or can be purple if feasting on purple cabbage) and leaves messy frass (droppings) on the plant. Learn these types of details for any pest you see attacking your veggies.
• Learn how it harms the plant. In the case of the cabbage moth, it's the caterpillar that does the damage. You'll see holes in leaves and leaf edges from its feeding. This is primarily a problem on younger plants.
• Practice hand disposal. If you can, crush the eggs, caterpillar or moths. This is often all home gardeners need to do. You'll be helped by beneficial insects such as parasitic wasps; different species parasitize the cabbage moth at different life stages.
• Erect a barrier. Use of a floating row cover (aka Reemay) can be an effective barrier to cover large plants or a large bed of seedlings, because it will keep the moths from laying eggs on the leaves. Floating row covers also exclude the brassica root maggot, which is active from late July to early September. Cover the entire planted area loosely and anchor it securely on the ground with stones or boards, or by digging the edges under the soil at the perimeter of the bed. It is important to apply the floating row cover before there are pupae present in the soil.
• Rotate your crops. Plant your overwintering brassica plants in a different location from where the spring and summer brassica crops were planted. This roation will confuse and disrupt any ongoing generations of the cabbage moth and other pests from easy access to their favorite foods.
• Find out more.  Take a class ,"Organic Gardening 101" For questions about what's happening in your garden, contact the Garden Hotline. For month-by-month food gardening tips, get a copy of our Maritime Northwest Garden Guide or pick up a copy of our new book, Your Farm in the City, and learn all about creating an edible urban oasis in your backyard.