Diseases By Crop
(Fact Sheets)
Photo Gallery
News Articles/ Disease Alerts
Diagnostic Keys
Virus Weed Hosts/ Rotation Lists
Resistant Varieties
Glossary of Plant Pathology Terms
Vegetable Guidelines
Vegetable IPM Links
Other Vegetable Links
Cornell Plant Disease Clinic


Downy Mildew in Cucurbits
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 close
Note 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 leaf
Yellow 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