Worms Killing My Zucchini

Question:

Hardiness Zone: 5a

bshale from Leon, Iowa

Answer:

Sounds like you have Squash Vine Borers. In the larvae or caterpillar stage, they are white with a dark head. They hatch from eggs laid in the soil by wasp-like moths, and then tunnel into stalks and leaf stems to feed. As they tunnel along eating the inner tissues of the plant, they push brown-colored waste out their entrance holes. The boring restricts the flow of water and nutrients to the plants and weakens their physical structure. In some cases, vigorous plants are able to survive the attack if the borer population is limited, but unfortunately, this is seldom the case.

Here are a number of organic methods for controlling them in the garden:

Trying to save infested plants:

1. Carefully slit open infested stems and remove the borer with a tweezers, and pack dirt around the slit.
2. Use a medicine dropper to inject infested vines with parasitic nematodes.
3. At the first sign of trouble, cut out and destroy infected stems or whole plants to reduce spreading.

To control them in the garden:

1. Interplant garlic and onion with zucchini.
2. Plow crops under in the fall to destroy pupae.
3. Release trichogramma (tiny wasps used for biological control) to attack borer eggs in soil.
4. Use pheromone traps for adult moths.
5. Use the proper variety of parasitic nematode as mulch around plants.
6. Cover vines with floating row covers early in the season (you'll need to hand-pollinate).
7. Plant early or very late to avoid the main egg-laying season.
8. Plant borer tolerant cultivars.
9. Clean up debris around the garden in the fall to reduce areas where they can overwinter.

Good luck!
Ellen