What Is Eating Our Zucchini Plant?

Decapitated Seedlings

• Newly emerging or newly planted seedlings in the garden are vulnerable to damaging conditions such as drought, windy mornings, bacterial and fungal conditions and insect attack. They need protection until they are stocky and established and better able to withstand tricky spring conditions. Seedlings that look like they've been bent and snapped near the base are victims of cutworms, moth larvae with chewing mouth parts that burrow in the soil and come out at night to feed. Protect fragile seedlings with cardboard collars cut from toilet paper or paper towel rolls and pushed about an inch into the ground around the stem of each plant.

Wilted Leaves

• Wilted leaves on a previously actively growing vine is an indication of bacterial or fungus wilt caused by some condition. Insects that feed on roots and crowns of plants leave them weakened and vulnerable to bacterial infections. Cucumber beetles are green with black spots or yellow with black stripes and feed in this way on squash, tomatoes and cucumbers. Their feeding introduces and spreads bacterial wilt and can quickly kill a plant. They also lay eggs on the undersides of leaves that hatch into yellow larvae that tunnel into the ground around plants and eat the roots. Beetles should be removed and dispatched as soon as they are spotted, as well as any eggs and larvae, by dropping them into a cup of soapy water. Larvae that have dropped to the ground and tunneled into the dirt can be exposed with a little light digging around the leaves where eggs are spotted.

Withered Leaves and Black Spots on Fruits

• Other signs of pests on zucchini plants include withered leaves and black spots on fruits. These are indications of squash bugs and vine borers, insects that suck the fluids from stems and growing fruit. Squash bugs are brown beetles with triangular heads and long mouth parts. Squash vine borers are winged bugs with red bodies with black spots. Both lay eggs on the undersides of leaves, which should be removed when spotted by brushing them off with an old toothbrush into soapy water. Adults can be handpicked and drowned in soapy water, although vine borers will usually be inside the affected stems, which have to be carefully slit open with a sharp knife to remove bugs.

Prevention Versus Treatment

• It's easier to prevent an infestation than treat it after it has started affecting your garden. Regular observation of zucchini plants and growing fruits gives you an opportunity to spot and eradicate insects before they spread and do too much damage. A daily walk through the zucchini patch to inspect plant stems, leaves and fruits reveals bugs, eggs and plant conditions in the early stages. Look at the undersides of leaves, at stems and in the soil around the base of plants.