balsam woolly adelgid infestation
Our Korean fir and Bristle cone pine trees appear to be infested with and damaged by balsam woolly adelgid. We live in Douglas County at about 6400 ft elevation. Please advise on treatment.
Douglas County Colorado
Can you please send photos of the damage?
Yes, I have photos. I'm figuring out how to upload them. Thanks for your patience.
It is difficult to tell from the photos what the problems are.
The bristlecone pine looks really healthy! It is normal for older (interior) needles to drop every year. Needles do not live forever, and after a few years (4-5 yrs, I think, for bristlecone) the old needles will turn brown and fall off in the autumn. The little white spots on the needles are resin flecks, which is a normal (and identifying characteristic) of bristlecones. If I am missing something, please point it out.
The Korean fir is definitely having problems. Did you prune the top branches, or is someone (like deer) browsing? Korean fir are beautiful trees but may not be the best choice of tree for Colorado. Are you providing correct cultural conditions for this tree? It likes bright shade or part sun, and moist but well drained soil with an acidic pH, and cool temperatures. These are not normal conditions for Colorado - we have blinding sun, baking hot summers, alkaline soil, and clayey soils that do not drain well. The brown needles might be a results of the tree suffering in our climate conditions and soils. I do not see adelgids on this tree; given the amount of brown needles, you would see fuzz all over the tree if they were causing it.
I cannot find any adelgids in the photos, though the webbing in third photo might be something left from some. Or it might be left from spider mites or spiders or caterpillars or something else. Is that sort of thing all over the trees? (If so I cannot see it.) Spring is when most insect pests are active, so check again next March to April, to look for crawling bugs and possibly new fluffy adelgids, on the new stems and at the bases of the needles. Do not spray anything until you actually identify a pest; it would be a waste of money and might kill beneficial insects.
Sorry that we cannot give a more definitive response. Given the time of year, it is hard to see insects, so just relax and take up the quest next spring!
Thanks so much for this information and advice. I'll keep watch in the spring for actual insects.