We have 2 massive Eastern hemlocks (Tsuga canadensis) both over 100 years old. The hemlocks are fighting a losing battle against extinction in the USA from the Hemlock Woolly Adelgid (HWA), a sap sucking insect that came from Asia. They are also vulnerable to fungal & decay species that attack the trees, especially if weakened by the HWA.
Anyway, there is a treatment, that needs to be done every 3-5 years which fights the adelgid, which lays eggs in sacs which look like small furry balls (see photo). The insect itself is almost microscopic & black in color & only feeds on new growth, injecting a toxin as it feeds. It is estimated that most untreated hemlocks in the Appalachian mountains will be dead or dying within the next 10 years.
Anyway, the only effective treatment so far is a pesticide. The also use horticultural oils & soaps which are environmentally friendly but are limited in reach & effectiveness. We have been investigating it as we didn't want any chemicals on our farm. Unfortunately, one of our hemlocks is really sick & is 50/50 on surviving, so I contacted an arborist, Gerg, to seek his opinion.
He seems to think he can save (if not repair) the sick hemlock & safely treat the 2 trees plus a much smaller one on our fence line with the pesticide & horticultural oils & soaps. So we are going for it to save these amazing trees. As a precaution, I have fenced off the bottom of our paddock so I can stop the chickens & goats entering the area for a while, just to be sure!
Gerg also suggested getting an arborist who climbs trees in to trim all of the dead branches off the sick hemlock to limit any fungal or decay species attacking it.
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