Oomycete causal agent: Plasmopara viburni

Symptoms: At the early stages, the symptoms are light green spots on the upper side of the leaves. As the disease progresses, these spots enlarge and form a yellow chlorotic region. Grayish white thick sporulation can be noticed on both upper side and bottom side of the infected leaves. Sporulations tends to be higher in the bottom side of the leaves. 

Management:. Cool wet conditions favor downy mildew occurrence and spread on viburnum. Apply fungicides early to reduce inoculum load. Check http://premier.cdms.net/webapls/formsloginRef.asp?/webapls for current labels in ornamental production.