Blighted Leaves

Various leaf spot fungi cause yellow, brown or black dead blotches on the leaves that frequently run together. Heavily infected leaves turn yellow or brown and fall prematurely. Cool, moist weather favors these diseases, especially when new leaves are developing. Shake out all fallen and diseased leaves from the center of the viburnum shrubs and destroy them. Remove all dead branches in the center of specimen plants or hedges to allow better aeration. Mulching helps prevent the disease from splashing up from the ground and infecting plants. Spray at weekly to 10-day intervals with sulfur or Bordeaux mixture or other copper fungicide, particularly in rainy weather.
(Note: Sulfur-based fungicides may harm some viburnum varieties. Test the sensitivity of your particular Viburnum by treating one branch and watching it for 3 days to see if any discoloration occurs. If the branch and leaves seem to be unaffected after that time, you should be able to use sulfur on the plant.)