Hemlock trees-yellow needles and dropping cones

Asked September 27, 2017, 6:04 PM EDT

Hello-I have two large hemlock trees (estimate 40 feet high). They've been dropping LOTS of cones most of the summer, much more than I ever remember. Also, they've dropping lots of needles most of the summer....I've seen yellow needles in the trees...a small percentage of all needles, but enough to blanket the driveway every few days. Question: is this anything to worry about? Thanks

Montgomery County Maryland

5 Responses

Hemlocks are susceptible to many insects, especially several scale diseases and hemlock wooly adelgid. Any of these could be causing problems. Please send us a photo of your hemlock's needles and twigs. Both closeup and mid-range. Then we should be able to be more helpful.


Hello ! My hemlocks had wooly adelgid about 20 years ago, then got treated for several years, and haven't seen any sign of them since. Attached are 3 or 7 photos (I'll try to send the rest). Thanks

We viewed your photos and they were not that clear. We cannot say for sure what is going on but here are some reasons for needle drop. The tree can be stressed due to drought or other site conditions, possible scale insects, and/or normal needle drop.
In general, the trees look too large for the area and are overgrown.
Take a look at our publication on scale insects and look for this. http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG81_Scale...

Also, we have been getting reports of heavy needle discoloration on hemlocks. This may be fall color which is normal.

For more information you may want to contact several certified arborists regarding the health of the trees and the best way to proceed. http://www.treesaregood.org/