Why are the trees in my yard failing?

When we experience a very dark and damp spring, the result is a lot of disease on the trees. Once the tree is stressed by disease, the pests move in to the weakened plant. Warmer weather should help, but watch for drought stress when it does get hot in the summer, as the tree is weak. Mulch around the base of the tree to help retain moisture during these times and use a soaker hose during the heat of the summer. A little fertilizer will help also.