As cankers enlarge and girdle the stem, parts above the diseased area lose color, make little growth, wilt or wither and die back from the tips. Infected branches often start growth later in the spring. The resin exuded from cankered branches is visible on dead bark after infected needles are cast. The fungus overwinters in cankered bark. Spores from fruiting bodies on cankered branches are spread by rain, wind, insects, birds, and man.
Infection occurs through wounds.
The fungus grows and kills the bark, then expands until the entire branch is killed. Integrated Pest Management Strategies 1. Prune diseased branches. Prune out all affected branches and burn or remove them from the site. Prune in late winter when it is sunny and the trees are dry.