I am growing cucumbers inside in a greenhouse and all of my cucumbers have this disease. I am growing Cool Breeze, Manny and Piccolino. They are all resistant to scab, mosaic virus and powdery mildew. So what could this be? The cucumbers are fine nothing happens to them just the leaves are diseased and even though most of the leaves are dead cucumbers are still growing not many though. Any ideas? Thank you
Downy mildew.
http://ipm.illinois.edu/diseases/series900/rpd927/
