Sumac Looking Sick
The leaves on our sumac are not developing. They are small, weak and curled, and pull off easily. Some brown, sticky, oozing earlier this spring on the trunk and branches. It looks like it needs water, but everything else around it is OK. It is still suckering. The tree is about 15 ft high and must be over 15 years old. What could be wrong?
This may be verticillium wilt.
Here is a link with more information.