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Downy mildew on pumpkin/gourd leaves


Upper and lower leaf appearance of early downy mildew infection of pumpkin (Cucurbita pepo)
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY


Downy mildew of cucurbits (Pseudoperonspora cubensis) can be a very destructive foliar disease as shown here on pumpkin.
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY
Small individual necrotic or chlorotic flecks appear on the upper leaf surface on downy mildew-infected leaves.Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY

Sporulation of downy mildew occurs on the bottom surface of leaves, giving a purplish or brown sooty appearance.
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY

Photos courtesy of T.A. Zitter, Cornell University, Ithaca, NY

downy midlew on pumpkin

downy mildew on pumpkin leafPatches of yellow tissue on pumpkin leaves due to downy mildew.
Photos Courtesy of M.T. McGrath, Long Island Horticultural Research and Extension Center, Cornell University
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downy mildew on pumpkin leaf
Purplish dark gray spores of the downy mildew fungus only develop on lower surfaces of leaves and are easily distinguished from white spores of the powdery mildew fungus.

down mildew on pumpkin leaf closeNote that downy mildew spots often have an angular appearance because they do not enlarge beyond major veins. This is most evident on the lower surface.

downy mildew on pumpkin leafYellow spots are on the upper surface of this leaf opposite where spores have developed on the lower surface. One section of this leaf has died because of downy mildew.
Photos Courtesy of M.T. McGrath, Long Island Horticultural Research and Extension Center, Cornell University