For those who have taken my orgainc controls workshop: use COPPER before it is a problem.
This new publication from UF/IFAS may be of interest.
Management of Cucurbit Downy Mildew in Florida
Cucurbit downy mildew is a major disase that affects over 40 species of cucurbits, like watermelon, muskmelon, cucumber, squash, and pumpkin. The classic sign of the disease is the presence of dark sporangia, a structure that holds developing spores, on the underside of infected leaves. As the disease progresses, it may lead to large necrotic areas that cause defoliation and a reduction of yield and marketable fruit. This nine-page fact sheet describes the symptoms and signs, epidemiology and disease cycle, host range and pathotypes, and the ways to manage cucurbit downy mildew.
http://edis.ifas.ufl.edu/pp325
This new publication from UF/IFAS may be of interest.
Management of Cucurbit Downy Mildew in Florida
Cucurbit downy mildew is a major disase that affects over 40 species of cucurbits, like watermelon, muskmelon, cucumber, squash, and pumpkin. The classic sign of the disease is the presence of dark sporangia, a structure that holds developing spores, on the underside of infected leaves. As the disease progresses, it may lead to large necrotic areas that cause defoliation and a reduction of yield and marketable fruit. This nine-page fact sheet describes the symptoms and signs, epidemiology and disease cycle, host range and pathotypes, and the ways to manage cucurbit downy mildew.
http://edis.ifas.ufl.edu/pp325