Avoid using insecticides that will damage the large beneficial insect population that usually accompanies an adelgid colony. Pearleaf blister mite will begin feeding on most of the ornamental pears, mountain ash, cotoneaster and serviceberry as soon as leaves expand. These eriophyid mites overwinter in buds and begin to feed on developing foliage. Blisters on foliage turn from pale green to purple to brown and black and may eventually cause defoliation. Control with hort oil shortly after bud break or Cygon applied to newly expanding foliage.
Hasty decisions can result in mistakes that can take years to correct, if ever.
Good reasons to prune include removal of dead or damaged wood, removal of suckers from the base of the plant, removal of water sprouts from the main branches, and correction and training of young trees. Avoid pruning these plants now. Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. John C. Nye, Dean and Director. Distributed in furtherance of Acts of Congress of May 8 and June 30, 1914.