Answer: Yellowing and dropping foliage can certainly indicate overwatering. Premature fall color can also indicate stress -- such as drought stress. In this case I would suspect overwatering, especially if it is in a low spot or growing in a slow draining, heavy, clay soil. Sometimes trees will defoliate due to flooding and then actually recover, so there is not much to do but wait and see. Some gardeners will try to open air passages to the roots to counter the water's exclusion of oxygen by poking holes in the soil. You can do this by digging straight down with a garden fork over the root area of the tree (extending beyond the branch spread). The difficulty in doing this is that walking on wet soil increases compaction so it might be counterproductive. You might also check with your local county extension to make sure they are not aware of any pest or disease isssues affecting this type of tree in your local area this year. I hope your tree recovers.
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