I call it the 'Florida Condition'.. it affects what seems like mostly temperate fruit trees.. even varieties that seem as though they're getting the right chill hours and such..
they stagnate in growth
they grow all sorts of lichens
stagnate more
and eventually succumb.. maybe fully.. without ever achieving a true adult tree size and won't produce much if anything at all.
Many times it affects stonefruits.. For example, methley plums, some older Georgia peach cultivars, flowering cherries. Some types of roses, blueberries, even pears. Seen it happen to crape myrtles too! Even wild persimmons!
I understand neglect may have something to do with it, but a lot of these trees are grafted onto hardy rootstocks, right? Is it the extreme heat and humidity during summer that does em in, or what??