Disease

• Bacterial wilt starts with wilted leaves that may recover at night. The disease progresses down the vine until the entire plant is wilted. Striped or spotted cucumber beetles spread the disease and are often noted in the garden. Phytophthora blight causes brown spots on the leaves, soft or decaying fruit, and shrunken, wilted vines. To manage these diseases, remove any diseased plant material immediately. Handpick cucumber beetles and drop them in a bucket of soapy water or spray them with a pesticide labeled for cucumber beetles. Plant zucchini at least 2 to 4 feet apart for adequate air circulation, and don't work in the garden while plant leaves are wet.
  
  

Insects

• Squash vine borers and squash beetles may cause damage to zucchini plants. The larvae of squash vine borers eat their way through zucchini vines, causing the plant to wilt or die. The first signs of squash vine borers are usually wilted leaves. Check the base of the plant for small holes filled with orange or green excrement. Trap adult vine borers in June and July by placing yellow bowls of water throughout the garden area. The color yellow attracts the borers and they drown in the water. Remove any infected vines from the garden. Squash bugs are gray to brown, leaf-sucking insects that cause wilted or damaged leaves. Handpick them or set traps of damp rolled newspaper in the garden. Shake the newspaper over a bucket of soapy water to release the trapped insects.
  
  

Cold Temperatures

• Zucchini, like all members of the cucurbit family, don't tolerate cold temperatures. If temperatures drop below 50 degrees F. for more than a day or two, the plants may wilt or the leaves may become brown. Cover zucchini with floating row covers to insulate them in the event of a cold snap.
  
  

Drought and Hot Weather

• Zucchini produce long roots and tolerate dry conditions, but they may wilt during hot weather. Wilting may occur in hot weather, even with moist soil conditions, but the plant will recover in the evening when temperatures are cool. If the plant stays wilted, provide additional water or investigate for other causes, such as disease or insect infestation.