Arborvitae die off

Question

Two years ago a small patch of dead space appeared on one of our arborvitaes on the west side of the house. It seemed to have stopped til this spring when it suddenly spread to the top of the tree. What is causing this? It recently has appeared on the back side of another about 7 feet away.

• 
• 

Answer 1

Unless you wrapped these guys up during the winter, they are probably showing signs of weather trauma. Here's an article about how to deal with that:
https://www.gardeningknowhow.com/ornamental/trees/arborvitae/winter-damage-to-arborvitae.htm
I'm also including an article on how to fertilize arborvitae: https://www.gardeningknowhow.com/ornamental/trees/arborvitae/fertilizing-arborvitae-trees.htm