Good afternoon and thank you for reaching out. It would be really helpful if you could attach a few photos to this question. Would that be possible? Photos really help our experts provide a solid recommendation.

Hi Harry and thank you for contacting Ask Extension.

Although hemlocks normally shed some of their needles in autumn, this doesn’t make the tree die. Evergreens, including hemlock, go through a natural cycle of dropping and replacing old needles just as deciduous plants do. The oldest needles are those that are closest to the trunk along a branch. These are the needles you should expect to turn yellow or brown and drop from trees and shrubs in the fall. Pines, hemlocks, spruces, and arborvitae shed some needles in the fall every year and produce new needles the following spring.

If trees are dropping needles from the inside (toward the trunk), then it is probably normal shedding. However, if the tree is losing its outer needles while the inner needles are still green, there may be something else going on. Environmental stressors such as too much water, drought, or herbicide exposure can cause needles to brown and drop. Once an evergreen branch has turned completely brown, there is little to no chance for recovery. Most evergreen trees, including hemlocks, only produce new growth at the tips of their branches. Once these growing points are damaged or killed, the branch will only continue to deteriorate. Dead branches can be pruned out at any time. However, if you do suspect some type of insect or disease problem, these branches should be bagged up and disposed of, not composted or left on the ground.

Based on your pictures it does not look like the browning is only on the inner branches so I agree with you, something else is probably going on.

Your problem could come from several sources, but it’s not possible to tell for sure from just your photographs. One possibility is Fabrella needle blight. Here is a resource from Penn State that lists some possibilities with a good picture of Fabrella needle blight.

https://extension.psu.edu/hemlock-diseases

Another possibility is Hemlock Wooly Adelgid. If you look closely at the needles and see small, white, cottony masses at the base of the needle, this could be the problem. When I zoom in on your picture it gets too blurry for me to see if that is the issue. Here is a resource with some good pictures.

https://www.canr.msu.edu/resources/hemlock_woolly_adelgid_e3300

If you are still not sure after looking at some of these references, I suggest you contact the Plant and Pest Diagnostic lab at Michigan State University. Send an email to <personal data hidden> and include some pictures. Include one picture of the entire tree and one with a close up of the needles, one of healthy needles and one of the brown needles. They may ask you to send in some branches for evaluation. Here is the link to their website. It includes links to the form to submit with your sample, instructions, and fees. There may be a nominal fee if they ask you to send in a sample. https://www.canr.msu.edu/pestid/