We had a flurry of discussion on this over the weekend. The diversity of possible answers shows you how difficult it is to do diagnosis with only some of the information available. That being said, several of you (Gail, Tom, Dave and Jimbo) all had portions of the problem identified. Here’s the whole picture:
As both trunks of this double-leadered tree have continued to expand in girth, they’ve created the perfect conditions for disease to occur in the narrow constriction between the trunks. Though I’m not a pathologist, I would agree with an initial diagnosis of slime flux.
In addition to the poor structure and disease issues, the location of this tree – next to a street, sidewalk, houses, and across the street from a school – simply shouts for removal before it inevitably fails and causes damage or injury.
Nice job – and thanks for doing your homework over the weekend!