Cucurbit downy mildew and late blight of potato and tomato are very devastating and rapid moving diseases. Though we do not have any reports of these diseases in WNC or our immediate surrounding areas, they have been reported in other parts of NC. Weather has been ideal for both of these diseases in our area, cool and wet. Also, because weather has been unsettled (many storms moving throughout the east coast) there is a chance that the spores of these pathogens could travel to WNC.
In fact, the Cucurbit Downy Mildew Forecasting site issued WNC a low risk warning on Friday. Cucurbit downy mildew has both been detected in eastern and central NC. On June 1, new reports of the disease were confirmed as close as Franklin, Nash and Wake Counties in NC. Cucurbit downy mildew is also tracking up the east coast into New Jersey. To view a map of current Cucurbit Downy Mildew outbreaks visit the CDM IPM Pipe website. Growers are advised to scout for this disease and to report to their local cooperative extension office if they need assistance or to report an outbreak.
Symptoms of cucurbit downy mildew on cucumber are angular lesions that start a pale green and progress to bright yellow and then finally brown (above). The best way to identify cucurbit downy mildew is to turn the leaf over to look for the downy growth of the pathogen's spores (below).
Late blight on a tomato leaf.
Again, these diseases have not been reported in WNC. If you suspect you have these diseases in your planting, please contact your local Cooperative Extension office for assistance. It is reporting and early detection that can save a planting!