Look at your summer squash plants to identify leaves that overlap or cross over from one plant to another.Pruning to remove unnecessary foliage can help minimize these challenges, as well as to minimize the impact of powdery mildew, which often affects summer squash plants. Summer squash plants grow large leaves and tend to sprawl, which means that their natural foliage can impede air flow and make it difficult for pollinators to find or access the flowers. Pruning summer squash plants can help keep them productive for as long as possible during the summer growing season. You may also want to have some plant starts on standby to replace ones that are killed by pests. Planting summer squash immediately after your last frost can help you get at least some harvest before these pests arrive in your area. Tip: Once the insects that tend to plague squash arrive, it can be hard to keep your plants alive. You can prune out severely infected leaves or try to treat them by applying a fungicide or natural remedy like neem oil, a mixture of milk and water, or a mixture of baking soda and Castile soap. Powdery mildew tends to develop when it is hot and humid. Powdery mildew shows up as whitish or grayish spots on the leaves, which spread over time. Powdery mildew - This is a fungal disease that commonly impacts squash, as well as some other plants.When the larvae hatch, they feed on the roots, which can also kill the plants. They lay eggs in the soil around the plants. Adult cucumber beetles feed on plants, which can kill them. They feed on all cucurbit plants, so they attack squash (summer and winter), cucumbers, and melons. Cucumber beetles - Some of these pests are yellow with black spots and some have yellow and black stripes.If you see adult squash bugs or their eggs on your plants, destroy them. As soon as they hatch, then nymphs start eating the plant. They also lay clusters of tiny red eggs on squash leaves.

They feed on squash plants, which can cause wilt and, ultimately, kill the plants. They range in color from gray to dark brown, with brown and orange stripes on their abdomens. Squash bugs - These insects resemble stink bugs.If you notice them before the damage is too severe, you can cut individual larva out of the stem with a knife and cover the damaged part of the plant stem with dirt. When the eggs hatch, the larvae bore into the base of the squash and feed, eating the plant from the inside out. Squash vine borers - These red and white moths lay their eggs at the base of squash plants.Squash plants are also often impacted by powdery mildew. Summer squash is often targeted by squash vine borers, squash bugs, and cucumber beetles.