viburnum foliage diease
Some of the leaves on my 15 foot 10 year old viburnum otorotisurum are sparse ,turning yellow with red.brown spots.They also have red/brown spots on the back of the leaves.It is spreading to nearby viburnums. Is this a fungus? Many leaves have dropped off and are no longer dark green. With what and when should I spray.It has been hot and humid where I live in savannah Georgia. Should I remove as many leaves as I can reach?
This article covers all the major viburnum diseases:
From your description, it sounds like you have a fungus, either Anthracnose or Cercospora. Here are the articles covering those syndromes: