Bacterial Wilt

• Bacterial wilt causes wilting, brown and dead foliage. It is caused by the bacterium Erwinia tracheiphila which causes a sticky, glue-like substance to clog stems and prohibit the flow of water and nutrients. To diagnose bacterial wilt cut a stem near the ground and hold your finger to the cut. Pull it away slowly, if a sticky substance comes away with your finger you're squash may have bacterial wilt. Bacterial wilt is spread by the cucumber beetle. Pesticides containing carbaryl, methoxychlor, or diazinon will help control the beetles but apply them before flowers have opened for the day or after they have closed to avoid poisoning important pollinators. Pull diseased plants immediately. Removal is not necessary if diseased plants are intertwined with healthy plants.
  
  

Downy Mildew

• Small yellow spots enlarging to irregular brown splotches and resulting in eventual leaf death could be the result of downy mildew. Occasionally downy mildew causes gray mold to form on the undersides of leaves as well. The disease does not effect fruit and doesn't always warrant control. Avoid getting foliage wet when you water as moisture encourages downy mildew. Check with your local university's extension office for advice regarding fungicides.
  
  

Alternaria Blight

• Wet weather and temperatures between 60 and 90 degrees favor alternaria blight. Older leaves near the center of the hill are affected first with dark brown to black spots often forming in concentric circles. Fruit is occasionally affected with soft spots. Crop rotation and removal of old crop litter are essential in prevention of blight. Fungicides containing anilazine or mancozeb are effective against alternaria blight.
  
  

Fusarium Wilt

• Fusarium wilt infects a plant's root system and causes discoloration, wilting and eventual death. Plants can also become stunted. Runners near the root crown may show brown streaking and roots will have a honey brown discoloration if cut open. Prevent fusarium wilt by planting resistant varieties and avoiding overwatering. There is no cure for fusarium wilt according to Clemson University so infected plants must be uprooted and destroyed.