Both these plants are in the rose family and can get fire blight which is usually a cold wet weather disease. However the death that this diseasecauses often becomes more noticeable in summer after everything else has leafed out and the newer growth turns brown. If every branch on the tree is dying and the death started in the summer, then the die off could be do to either drought or drowning. Both look the same above ground. In addition to death of branches, the leaves below the dead areas should look limp or wilted and discoloring. Try our disease site called focus on plant problems (new name) or focus on plant diseases (old name) for more info on diseases. If possible e-mail me some pictures of the sick trees for a better diagnosis.
