What's Wrong with my Arborvitae?

Asked March 29, 2018, 5:34 PM EDT

We have an arborvitae (I think) that has been growing in the same spot for many years. It was already very large when we bought our house in 2002. Nothing has changed in recent years except that our neighbors cut down a very big spruce tree about 30 feet away last summer. The tree is on the NE corner of our garage, the closest tree to it is a black walnut tree about 15 feet away (to the south). This winter, the arborvitae has started looking very "scraggly" with many "leaves" falling off and now we've noticed that the tree just looks kind of wilted. The bark has developed some streaking that we have never noticed before (more on the north side of the tree). We have another arborvitae on the other side of the garage that looks healthy. I'm worried that it is just getting old. Thank you!! I've read that deer and rabbits can cause this type of damage, but we live in downtown Buffalo so no deer and the damage is too high to be from rabbits. We do have a lot of squirrels.

Wright County Minnesota

1 Response

Thank you for the question and providing good supporting information. Your tree does look like an arborvitae. They can live for more than 50 years if conditions are right so it's hard to say if the tree is nearing the end of its life. Arborvitae are known to be tolerant of juglone, a chemical produced from black walnut trees so I don't think this is the problem. Juglone in the soil around and under black walnut trees prevents many plants from growing near it.

I can try to help you figure out what is causing the bark removal but I can't really tell from the photos if anything else is going on. Provided there has been no human mechanical damage this winter from such machines like snow plows, you could consider squirrel damage because they are known to strip bark in the winter/early spring. This would make sense in your case from the location of the damage high up on the tree. We don't know for sure why squirrels do this but reasons might include searching for moisture and food. I'm speculating that with the removal of the large black spruce, squirrels were displaced and had to look for other sources of food and protection this past winter and maybe chose your arborvitae. This is just a guess. Please read these publications to learn more on barkstripping by squirrels and how you might control try to control them. It will be difficult because squirrels are so numerous.

Thank you for contacting Extension and good luck!