It is impossible to tell just by the limited description and photos shown what is wrong with your maple. more photos specific to the damage would help as well as a cross section of a dead stem/branch. It would help to know where you are located, as well.

Pseudomonas does not usually kill very rapidly. Starts out as stem dieback but can develop into cankers lower on the tree.....not exactly what I am seeing here. Anthracnose also tends to be slow in causing death - trees often live for years with the problem. Verticillium wilt can be very rapid but usually shows up a bit later in the season.

My suggestion would be to take photos and any damaged/dead material you can easily remove to your local extension service for a complete diagnosis. Many of these diseases DO require the skills of a plant pathologist for accurate assessment. And you will need that before any kind of treatment can be approached, if at all.