Q.Weigela that appears to have some kind of black disease
My Weigela has a black growth on the branches, however, it did bloom this year. I cut back several dead branches earlier but I did not see this black growth which could be a black slimy fungus (it looks like black molasses) possibly. The branch just snapped off. Has anyone ever seen something like this?
I believe your shrub is infected with a fungal disease; these occur in Azaleas also.
"Two fungal diseases can cause azalea branch dieback: Botryosphaeria and Phytophthora. There is no practical chemical treatment for either disease, although fungicides may prevent the disease from spreading to other plants."
Read more at Gardening Know How: Are Your Azalea Branches Dying: Learn About Azalea Dieback Diseases https://www.gardeningknowhow.com/ornamental/shrubs/azalea/azalea-branches-dying.htm
I would remove the shrub and dispose of the plant; do not compost.