You can tell the difference between underwatering and overwatering a tree by the soil and the foliage.
When a tree is overwatered it causes soggy soil and limp and soft leaves which can turn yellow or brown in color and wilt.
When a tree is underwatered it often causes dry and crumbling soil and leaves which droop or curl.
An over watered tree will look like yellowing or wilting of the leaves and the over watered tree may also have fungal growth around the base or algae or moss around the base of the tree.
The soil around the base of the over watered tree will also be consistently wet and even possibly be soggy.
And with an over watered tree, new growth may wither prematurely or even turn light green or yellow and the leaves of the over watered tree may even appear green but be brittle.
The most common signs of an overwatered tree are leaves turning yellow, which can also be accompanied by drooping or wilting of the leaves.
The soil around the base of a tree should be moist but not overly saturated or soggy and if the soil around the base of the tree is overly saturated or soggy then the tree is being overwatered.
Any excessive moisture can also encourage the growth of fungi such as algae, moss or mushrooms around the base and the trunk of the tree.
And even if the leaves of the overwatered tree are green they may be brittle or even break easily which indicates that the tree is overwatered.
And if the tree appears to be wilted even though the soil around the base of the tree is wet, it's a very strong indication of the tree being over watered.
In some cases a tree will naturally recover from being over watered as long as you stop watering the tree and allow the tree to use up the water and recover.
If your tree is over watered you should scale back on the watering frequency immediately and allow the soil at the base of the tree to dry out between watering's.
On average it takes an overwatered tree 7 days to 14 days to recover from over watering.