Wet years following drought years can cause problems with tree decline. The following is an article on the subject.
Of great concern are moisture extremes (excessive moisture in poorly drained areas as well as mid-season drought). Landscape trees throughout Delaware have been stressed in previous years by prolonged moisture extremes, and it often takes trees five or more years to recover. Not only does moisture stress impact the immediate growth and development of plants, it also predisposes them to other diseases (especially cankers caused by Cytospora, Botryosphaeria, and Nectria) and insect pests (such as borers). Keep this in mind during the next few years when monitoring landscape trees and shrubs for plant health.
Adapted from "Diseases of Ornamental Plants: End of Season Notes" Ann B. Gould, Ph.D., Specialist in Plant Pathology in the November 12, 2009 edition of the
Plant & Pest Advisory, Landscape, Nursery & Turf Edition, A Rutgers Cooperative Extension Publication http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/ln111209.pdf