The backside of three arborvitae trees, maybe 8’ tall, have been up against a 6’ wood fence for years. We are now replacing the fence and can see that the backside of one tree has some brown rusty foliage. No luck with google for a solution. Could this be red spiders? Or a disease? What would you suggest for treatment? Trees are otherwise healthy. Thank you.
Clackamas County Oregon
Here is a general article about arborvitae care with comments about fall browning. Hope this helps.