Question
Mr. Hyland: Most foresters I know dread tree pathology questions because there is so much variation in conditions and agents, yet the problems persist in tree death and it attracts lots of attention. I'll try to be specific to narrow down possiblities. The questions: I work here in the woods in Western Washington. Here, right now cutting alder on Whidbey Island, I have seen that lots and lots of the native western white pine is dead or dying. Some uninformed opinion goes that this pine is stuff brought over from east of the Cascade Mountains and is simply not genetically suited to locally wetter conditions. I see thought that really back in the woods in areas far from any place where people would transplant alien pine, what appears to be naturally regenerated native pine is dying or dead, with maybe one-half the pines still thriving. I heard this problem is caused by a pine blister rust not by a bark beetle. As the trees decline I have noticed a formation of orange bleeding cankers up the bark. Is this a virus, bacteria, fungus or some little insect? Is there an intermediate host involved and is this apparent disease an exotic infection or is it native but now encouraged by the western drought. On another problem, especially now east of the Cascade Mountains, how does the drought there promote bark beetles to successfully attack pines, spruce, fir, etc. I have heard amongst loggers that the drought simply dries the trees' pitch production up somewhat so that the beetles are not as oftenly mechanically stopped by the pitch. Also I have read that with slightly warmer average temperatures the beetle larvea are surviving the winters better. [Areas around Homer, Alaska are a good example of this]. Is this theory about beetles, drought and warmer winters true? Thank you for the use of your valuable time.

Answer
Yes it is White Pine Blister Rust. Any disease that has the name "rust' associated with it has two hosts to complete its life cycle. In this case the hosts are White Pine and Ribes (gooseberry and Current plants). In the Spring orange spores are produced on the swellings of the disease on the stem and branches. these spores are wind blown to the Ribes plants where more spores are produced and these spores from the Ribes plants are wind blow to the pine needles reinfecting the pines. Drought does not effect the spore production in fact the dieases needs a cool moist spring to produce better spores. This disease is a fungus. Here is a web link to more information on Blister Rust. http://ext.nrs.wsu.edu/forestryext/foresthealth/notes/whitepinerust.htm

Second question--Drought does play an important role in Epidemics of Bark beetles. It is a combination of the tree not producing as much sap and the because of the lack of water the tree is under stress and the growth slows and the beetles can enter the bark and more easily kill the tree. This is more true for older trees--simular to humans when we get older we begin to slow down on growth and are mre suceptable to diseases. The beetles attack the trunk of the pines and bore into the bark if there is a good flow of sap then some of the beetles are "drowned" by the sap flow--during droughts these beetles survive. As beetle population build the numbers of beeltles will off set the amount of sap and even "healthy" pines will be killed. During normal winter months the beetles population rates slow to almost nothing and they "sleep" through the cold months--during warm winters the beetle life cycle continues and the popluation although at a slower rate will increase. Here is a web link to a site that will answer any question on Mountain Pine Beelte. http://www.pfc.forestry.ca/entomology/mpb/outbreak/synchrony_e.html