White pine blister rust, caused by the fungus Cronartium ribicola, is a serious disease of white pines, causing great losses of timber. North American white pine species, including bristlecone, limber, sugar, eastern white, southwestern white, western white, and whitebark, are highly susceptible. Currants and gooseberries (Ribes spp.) are also attacked and serve as an alternate host for the fungus that causes white pine blister rust. The disease does little harm to currants and gooseberries.
On white pine, the symptoms include dead branches; chlorotic (yellow) foliage; branch or trunk girdling by lesions that exude resin or sticky, yellowish fluid; cankers that are diamond-shaped to elliptic with a dead center surrounded by a band of yellowish-green infected bark; light yellow-orange spore-bearing aecia; and death of the tree.
Blister rust management: a) Remove and destroy susceptible Ribes species and infected pines. b) Plant only disease-free resistant varieties of Ribes. Some examples of resistant varieties of black currant are Consort, Crusader, Coronet, Ben Sarek, and Ben Nevis. c) Do not plant red currants and gooseberries near white pines. d) Fungicide applications are not very practical for white pine blister rust.
