Flowering Plum

Perhaps someone has a clue what could have happened.

I had a 12' nice, beautiful healthy flowering plum suddenly die shortly after fully leafing out this spring. No sign of borers, no leaking sap, firm in the ground, no evidence of gophers. The leaves wilted on the tree, one half first, then the other, then the leaves turned crisp, but did not drop. It was completely dead within 2 weeks. No leaking sprinkler pipes, normal irrigation. The only thing I can think of is the lawn guy fertilized about the same time (I can't remember which came first), but the grass is not burnt, and I deep watered the tree right after I first noticed symptoms just in case....One other symptom, the young dead branches when cut, are kind of purplish inside where it is usually green.

Any thoughts? I'd hate to have a disease that could spread to the neighboring tree.

I could be wrong here, but this totally sounds like over-watering. Especially if you gave it another deep soaking when you first saw the symptoms. Wilting leaves is usually a watering problem and if adding more water only made them crisp up, then its possible there was too much water in the soil (roots couldn't breathe).

To me, it doesn't sound like a disease. And if it was over-fertilized, you most likely would have seen discoloration in the leaves and possibly spotting.