Tissues are often resin-soaked. In the fall, small black fruiting structures of the fungus can be seen on needle bases. The annual death of buds and shoots causes trees to decline gradually from the bottom branches upward. The fungus may also penetrate young stems and cause cankers which eventually girdle and kill branches. Fungal spores are spread during wet weather from early spring until fall.
Infected cones serve as a source of spores.
Promote good air circulation by adequate spacing and weed control. Trees may be pruned to improve their appearance, but this does not control the disease. 1992 issue, pp. Prepared by Paula Flynn , Department of Plant Pathology Iowa State University , Ames, Iowa. This information subject to a usage policy .