Powdery mildew shows up as white, dusty spots on both the top and undersides of leaves. These spots spread rapidly and soon cover large areas of the leaves, which then yellow and shrivel. It also produces a good number of fruit per vine, averaging 15 pounds apiece under S.C. conditions. These varieties produce small fruit, generally about 5 pounds apiece. The giant pumpkins are also partially resistant to another pumpkin disease, downy mildew, which kills vines in wet weather.
Downy mildew starts as hundreds of small yellow flecks on leaves.
The flecks enlarge, turn brown, and the leaves shrivel up. To protect pumpkins against downy and powdery mildew, spray weekly with a home garden fungicide that includes daconil. Check the active ingredient list on the label, as daconil is sold under several different brand names. The Oct. 1997 issue has powdery mildew reactions for 32 varieties, and Jan. 1998 has yield data for these varieties.