Summer squash is a tender, warm-season vegetable native to North America. The various species are members of the Cucurbitaceae family, meaning they're related to cucumbers and melons. What makes summer squash different from other squash is that every part (skin, flesh and seeds) is edible. Summer squash is harvested before the rind hardens, and the somewhat fragile fruits cannot be stored for long periods of time. Popular varieties include zucchini, straightneck squash, crookneck squash and pattypan.
Blossom-end rot, also common on tomatoes, can affect summer squash. It occurs during hot weather. Curly top, caused by the curly top virus and by insects, causes the squash's leaves to curl and eventually kill the plant. To control it, destroy infected plants, water and fertilize regularly and rotate your crops. Powdery mildew is a disease that shows up as a white powder on the squash's leaves. Use a soaker hose to avoid wetting leaves and plant resistant varieties. Verticillium wilt causes squash plants to turn brown, wilt and die. Destroy plants infected with the disease and do not compost any of the diseased foliage.
The cucumber beetle has an oval, bright yellow-green body with spots. As it feeds on squash foliage and stems, it spreads the bacterial wilt organism, which will kill your plant. Control the cucumber beetle by planting resistant varieties or using a foliar insecticide. The squash bug is dark to grayish brown on top, with a tan or light gray color below. It causes brown blotches on the squash foliage or stunted growth. Pick squash bugs by hand or use an insecticidal spray. Aphids are soft, tiny green bugs that suck the fluids from squash plants. They leave a sticky honeydew behind, which attracts ants, and the leaves turn yellow. Remove them with an insecticidal soap or a strong spray of water.
Summer squash seeds do not germinate well in cold soil. Clemson Extension recommends not planting summer squash until your soil is at least 60 degrees F at a depth of 4 inches. Using black plastic mulch under your squash plants warms the soil, conserves moisture and reduces weeds. Space summer squash plants 15 inches apart in 3-foot rows. If you plant them in hills, space the rows 4 to 6 feet apart, with hills 3 to 4 feet apart. Harvest summer squash early, when the fruits are no longer than 4 to 6 inches.