Dry corky spots up to 1/2 inch in diameter appear on the fruit. A sticky substance may ooze from the spots. In moist weather, a dark green velvety growth covers the spots. Fruit may be cracked and decayed. White or gray spots appear on the leaves. Dead tissue falls out of these spots, leaving ragged holes.
At the first sign of the disease, treat plants with a fungicide labeled for scab, following label directions. Clean up and destroy plant debris after harvest. Rotate your cucurbit planting site every year, and grow resistant varieties.