Emerald green arborvitae generalized yellowing

Asked February 20, 2019, 5:09 PM EST

I have a fence line of 12 arborvitae. Been growing without much attention for the past 25 years. Planted about 5' apart. The site gets direct sunlight until about 1:00pm in the summer. This past summer one began to yellow overall -- (generalized color change.) The tree is now a "toffee" yellow/brown. Uniform color. None of the other trees in the line are showing abnormal color changes this winter. This is the first time I have had any problem with these trees other than deer damage, from which they are recovering. I am not optimistic that this tree is viable If I pull this tree and replace it, what considerations should I give to soil preparation and or sterilization? Poor drainage has not been a problem in the past. The site is on a slight incline and drainage is good. ???Other considerations??? jpg attached

Calhoun County Michigan

1 Response

Hello,

It does sound like this shrub has died. Your picture wasn’t attached, so you can try again and I will take a look. But, if it is just browned leaves there isn’t much I can tell from a picture.

Here are some things to do-

Submit pictures and branch samples ( and root samples if possible) to MSU Diagnostic lab. Choose branches that still show some life if there are any. There is a fee for diagnosis- see fee schedule on their website. The lab may be able to determine if there is a disease or insect issue. However, the longer the shrub has been dead and dried out, the less likely a diagnosis can be made.

https://pestid.msu.edu

When you remove the shrub, dig around the roots and see if they look soft, mushy, or very dry and brittle, or unusual in any way. You could shake the dirt off and take pictures and send them to the lab with the branch samples.

Sometimes one or two shrubs will die because, over the years, they are more stressed by root zone competition, or too much shade, or exposure as plants around them grow up.

There are root rots that occur. During drought stress, plants are more vulnerable to root rot. https://extension.tennessee.edu/publications/Documents/W289-D.pdf

https://pestid.msu.edu/plant-diseases/phytophthora-root-and-stem-rot/

The MSU Plant Diagnostic lab may be able to test for root rot- please call the lab if you are interested in this. ( web site link is above).

Remove as much of the dead plant’s roots as you can without damaging or cutting the neighboring shrubs’ roots.

To get all plants at the same height again will take several seasons. When pruning, don’t remove more than 1/3 of the top growth per season.

When planting a new shrub, be aware of how deeply you plant. Even nursery stock in a container, or balled and burlaped, can be sitting too deep in its soil ball. Here is a link with correct planting procedure, which is important to the new shrub’s health.

https://www.uaex.edu/publications/pdf/FSA-6128.pdf

The new shrub will need to be given deep, thorough supplemental water for the first two seasons during times of dry weather, from spring through late fall.

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