Q.All 3 of my 10 year plus healthy viburnums are not budding this spring. They look dead. What happened?
There were no signs of disease last year, but this spring all 3 viburnums are not budding. They have an occasional flower but most of the plant is leafless

Certified GKH Gardening Expert
It appears to have cankers, which would suggest that there is an infection at the root zone. Usually, by this point, the damage is significant, and hard to control.
I can recommend a treatment that may help, though.
Using DOLOMITIC lime and WETTABLE sulfur, in tandem, can help kill off infections in the soil. Just apply to the soil as per the instructions, and you should see some sort of recovery by next year.
Doing this once or twice per year is a really good preventative method, as well. It also provides essential nutrients such as calcium, magnesium, carbon, oxygen, and sulfur.
This article will give you more information on root infections: https://www.gardeningknowhow.com/plant-problems/disease/root-rot-in-garden-plants.htm