Emerald Green Arborvitae

Asked September 15, 2020, 4:00 PM EDT

I have a row of arborvitae 20 yrs. old or more . I am experiencing them turing brown and completely dying. Why is this happening ? It isn't every one just some {4{ in .a cluster next to one another/

Cumberland County Pennsylvania

1 Response

Thank you for your question. You mention that there are several of your arborvitae grown in a cluster. Please read the following information on air circulation. Please also keep in mind the climate in your region which, if it's anything like ours in Delaware County, has been extremely warm and humid with a lot of rain since spring, ideal conditions for breeding fungi. With a little detective work, you may be able to zero in on the reason your arborvitae are failing. I hope all of this information is helpful.

The average life span of the emerald green arborvitae is about 25 years. This represents the life span under ideal conditions. The shrub's life can be shortened by salt contamination, deer depredation, and rarely, disease or insect damage.

In very humid conditions, fungal diseases can be a problem - needle and twig blight are caused by fungi, especially if air circulation is poor; help prevent this by improving air circulation.To control blight, prune off all affected branches and treat with a fungicide. Please try to find one that is specific to needle and twig blight and that is not harmful to humans, pets, or the environment.

There are two other possible conditions that can affect arborvitae. Please read the symptoms carefully to determine if either of these is the problem you're experiencing:

Canker diseases cause foliage to wilt and turn yellow or brown. A resinous oozing from bark of infected branches is often present during canker attack. Cytospora canker causes reddish brown cankers and sunken places in the bark. Prune out diseased branches, cutting back to healthy tissue. Fertilize plants lightly to promote healthy growth, but avoid heavy fertilization, which can cause susceptibility to disease. You must destroy plants infected with cankers on the main trunk, as there is no treatment to restore the tree to health.

Fungal attacks of roots are called root rot, while attacks on the tree trunk just above the soil line are called butt rot. Root rot and butt rot both cause foliage of "Emerald Green" arborvitae to turn brown. Caused by several different types of fungus, but having the same result, affected trees die from these diseases. (NOTE: Since your trees are 20 years old, I doubt that either of these fungi are the culprits - J.) Avoid rot diseases by planting "Emerald Green" arborvitae in well-drained soil and do not overwater. Prevent injury to tree roots and trunk by mulching and protecting from mechanical damage from lawn mowers or other equipment.