Is it possible to over-water a fruit tree? What are the signs of over-watering a fruit tree?
It would be pretty hard to over water anything in open ground, unless the area was actually flooded, or there was a solid surface below the soil. In pots, so long as there are drainage holes which are not blocked,its next to impossible to overwater plants in those too, although some succulents and cacti wouldn't appreciate being watered too often.
The usual problem that occurs with trees or shrubs sitting in waterlogged ground is root rots caused by fungal infection.
From the Arizona Master Gardener Manual on fruit trees:
…frequent irrigation in spring can cause yellow leaves, root rot and waterlogging.