Answer: Based on your description the trees sound as though they are severely stressed. Drought can certainly cause this type of stress, as can canker -- to which these trees are quite susceptible, and other diseases. The white spots might be lichen which can sometimes appear on ailing trees, but in and of itself does not damage the tree. I would suggest you consult with a professionally trained and certified arborist, or possibly with your local county extension to try to obtain a specific diagnosis of the problem(s) and then based on knowing that, determine how to proceed. If a chemical control is needed, your county extension should have the most up to date information on what and how/when is best to apply it.
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