I need help identifying some twig die-back. It has created a big hole in the center left of my tree. When I sliced the small twigs open I see dark heartwood, but I didn't see any black rings around the heartwood. Is the dark heartwood indicative of verticillium wilt? These are all small twigs, measuring about 1/8" diameter at the base.
If not that maybe another, such as bacterial dieback. http://ipmnet.org/plant-disease/pla...t_alpha=Select&host_text=maple&submit=++Go!++