Sick Arbor Vitae
Hello! I have 12 Arbor Vitae trees in my yard and have notice that two in particular look sick. They are directly underneath the neighbors Rose tree and I'm wondering if that is the culprit or simply coincidence. A cursory google search makes me think that I'm not over-watering them, and I think they were planted correctly 2 summers ago so I don't think it's root rot but I don't know how to check that. Could it be some sort of blight? The leaves are brown and falling off. All of the other trees seem just fine. Also wondering what precautions I should take to keep them safe over winter. Thanks!
Hennepin County Minnesota
It's normal for some inner arborvitae foliage to turn brown and be shed at this time of year. See normal fall needle drop here:
However, we agree that the foliage on the plants in your photos appears to be more sparse than one would expect on healthy plants.
Too much shade is the most common cause of arborvitae leaf and branch thinning. Mite, miner and other insect damage can have the same effect.
There is little or no chance that what has defoliated the nearby rose is affecting your arborvitae.
Because we can't accurately assess the arborvitaes' health or diagnose a problem by viewing the photos, you may want to ask a certified arborist to do that onsite and recommend a course of action.
Being sure the plants have plenty of water until the ground freezes is the most important thing you can do to prepare them for winter.