Hello Kurt,

It is difficult to see the scale in the photo. Read about Fletcher Scale here: https://extension.psu.edu/fletcher-scale

Certainly, there is serious dieback of the branch. With a picture of the whole tree, a better assessment can be made. MSU Extension’s Plant and Pest Diagnostic Lab can provide a complete diagnosis and treatment of the problem. To learn how to send a sample/photos, go to: https://www.canr.msu.edu/pestid/

A certified arborist can assess the tree. To find an arborist in your area, go to www.treesaregood.org, the website of the International Society of Arboriculture.

Thank you for contacting Ask Extension.

The brown "lumps" at the end of each dying branch are what I thought were Fletcher Scale.  However, in all the online pictures, the Fletcher Scale appears on the middle of the branches, rather than at the very ends, so maybe it's something else.

The arborvitae this was taken from is mostly dead with just a few live branches near the top.  I can certainly bring in the entire bush for identification if that helps.

Kurt

Hello Kurt,

There are many factors that cause an arborvitae to brown, including improper planting, lack of water, too much water, environmental changes that could affect drainage and lead to root damage, insects, diseases and winter burn.

How you water may have an impact. If an above ground sprinkler hits the branches of the tree, they may break the branches and an attack by an opportunistic fungus such as Phomopsis twig blight. Read more about Arborvitae diseases here: https://extension.psu.edu/arborvitae-diseases

Insects such as spider mites may cause damage to arborvitae. Check for mites by placing a white paper under a branch and give it a shake. The moving black dots that fall to the paper are mites. Read more here: https://extension.psu.edu/spruce-spider-mite

Attached is another article about stress related evergreen dieback: https://www.extension.purdue.edu/extmedia/id/id-477-w.pdf

It could be caused by damage to the roots. Girdling roots could strangle the stem and prevent water and nutrients to reach the rest of the tree. There also may be other damage to the tree just above soil level. Without a picture of the trunk of the tree where it enters the ground, it is impossible to speculate on what is causing the problem.

You said that you could bring in a sample—I assume that would be the Extension Office in Cadillac. But it is unlikely they can analyze the problem. For a definite diagnosis, you should submit a sample and pictures, including pictures of the whole tree, and the branch to MSU Extension’s Plant and Pest Diagnostic Lab: https://www.canr.msu.edu/pestid/

Thank you for contacting Ask Extension.

Thank you. 

We live down state and drive through Lansing on our way home.  I'm planning to dig one of the partially dead arborvitae and bring it to the MSU Plant & Pest Diagnostics, Center for Integrated Plant Systems in Lansing on Monday, July 8.  I'll also bring pictures of the entire hedge so they can see very healthy arborvitae on each side of the one that is mostly dead. 

I assume that is the best way to find out what is wrong and how to correct the problem.

Kurt

You should check out the web site to establish how to submit samples to the lab.