Mountain Hemlock shedding needles and dying

Asked July 17, 2020, 4:43 PM EDT

I have a 35' Mountain Hemlock that is shedding needles rapidly and looks to be dying. It is 30 years old that I planted in a grove of 3; one other tree next to it died like this 5 years ago. We live in Sammamish WA which is about 500' above sea level and in foot hills of Cascade Mountains. I have been watering a lot lately to try to rescue, the only thing that I might have done incorrectly lately is that I put a new layer of approx. 2-3 inches of bark around the base in October of 2019. Is this a fungus or something in soil? What would you recommend? Thank you!

King County Washington

1 Response

Hi--from what I can see from your tree, the crown--the very top of the tree-looks good. That pretty much rules out root rot and cumulative drought stress related problems. What's left is needle blight fungal disease. See https://pnwhandbooks.org/plantdisease/host-disease/hemlock-tsuga-spp-shoot-blight For homeowners, the only legal control is to use copper-based fungicides. I'm not sure that would help with the size of your tree. My suggestion would be to call an ISA certified arborist--these folks are highly trained and certified to diagnose and treat tree diseases. It would also be a good thing to get confirmation of needle blight. To find an ISA Certified arborist near you, check on this website: https://www.treesaregood.org/findanarborist