Squash varieties comprise both winter and summer varieties. Summer Patch contains zucchini, which is harvested while still immature and the skin is easily penetrated. It grows well in a sunny place with well-drained soil. Although zucchini is fairly simple to grow, insects and other problems can cause leaf curl. Offering proper growing conditions can help zucchini plants withstand insects and disease.

Squash Leaf Curl

Squash leaf curl is a virus which affects many species of squash, including zucchini. Symptoms of this virus contain upward curling leaves, mottling of mid-vein leaf portions and small and abnormally developed fruit and flowers. Whiteflies frequently carry the virus, so control of these insects and the weeds across the zucchini which frequently harbor them. Other techniques of control include instantly destroying infected plants and alternating the planting area.


Aphids are tiny insects which may be green, yellow or dark and damage plants by feeding on the plant juices. The insects are most frequently found on the undersides of leaves. Affected zucchini plants show symptoms such as leaves which curl under, turn yellow or brown and become deformed. Aphids can transmit diseases and secrete honeydew that contributes to sooty mould. Treat zucchini with insecticidal soaps to control aphids.

Calcium Deficiency

Calcium deficiency in zucchini plants triggers symptoms such as chlorosis between leaves, stunted development and cupped, distorted leaves. New plant development indicates these symptoms first. Should you suspect calcium deficiency, conduct a soil test or analyze the foliar nutrients to affirm. To avoid calcium deficiency, amend soil with lime prior to planting zucchini if the soil test indicates it is needed. It’s also wise to use a balanced fertilizer.

Keeping Zucchini Healthy

To maintain zucchini healthful, provide the plants rich soil and feed occasionally using a balanced fertilizer. The plants require regular water and a sunny site. Spacing is important to prevent disease, so distance plants at least three feet apart. You are able to control insects by checking the undersides of leaves and crushing any egg clusters you visit. The egg sacs are usually yellowish-brown in color.

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