I have a row of about 50 arbor vitaes all right next to each other and they seem to be dying. People have asked if they are near the road due to salt issues and they aren’t. I’ve tried spraying them with stuff for mites and applied it twice over 3 weeks and it doesn’t seem to be doing anything. Help!?
The most common cause of death of shrubs and trees is people piling mulch up against the bark of the plant smothering the bark and strangling the tree. Get under there and push any mulch or soil away from the trunks until you find the root flare or original level of the soil and keep it that way. Mulch is a good thing away from the trunk but deadly if piled against the bark. Likewise, if they were planted too deep and soil was backfilled against the bark. Keep them well watered in the fall as well to help reduce winter damage.