I have recently noticed many local Douglas firs turning brownish red (many needles dying), with some trees having entire limbs apparently dead or dying. I've seen this here in Corvallis, in the coast range, in the Portland area and in the Columbia Gorge; and I have seen it in young forest stands (20+ years) as well as individual 100 year old trees on urban city lots. (An arborist in Portland diagnosed one of these older trees as Swiss needle cast.) What is going on? Will the trees die? Is there treatment possible?
We think that most of the problems this year are drought related - trees are stressed and then other insects and disease can more easily attack the trees. I spoke with our Forest Health Specialist, Dave Shaw. He recommended that you look at the following article: Many Douglas-fir with dead tops and branches in the Willamette Valley this year. I wish we had better news.