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Sunday - August 01, 2010

From: St. Louis, MO
Region: Midwest
Topic: Trees
Title: Disease of eastern red cedars (Juniperus virginiana)
Answered by: Nan Hampton

QUESTION:

I have multiple Eastern Red Cedars spaced in my woods which are sick and dying. Some were transplanted years ago, others are volunteers, all are less than 4 ft tall. The foliage turns brown in various places throughout the plant top to bottom and this seems to spread without cause. On some branches it starts at the tips, other times not. There are no cysts, or growths and no visible fungus, mold or pests. I live in St. Louis, MO. This started in the spring and continues through the summer. They are not drought stressed. Do you know how to save my trees? Thanks.

ANSWER:

Our focus and expertise here at the Wildflower Center are with plants native to North America, but we aren't necessarily experts on their diseases and how to cure them. We hope, however, we can point you in the right direction to find resources that can help you with your Juniperus virginiana (eastern redcedar) problems. There are several diseases that are listed as common to the junipers, but the three with symptoms that sound most like that of your trees are:

1) the Phomopsis and Kabatina Tip Blights of Junipers caused by the two fungi Phomopsis juniperova and Kabatina juniperi. This article lists control measures including watering, fertilizing and pruning advice, as well as methods for chemical control. Here is more information on Phomopsis blight and on Kabatina tip blight.

2) the fungus Pseudocercospora juniperi (syn. Cercospora sequoiae var. juniperi) that causes Cercospora Blight of Juniper. The Juniperus scopulorum (Rocky Mountain juniper) is most susceptible. Although Eastern Red Cedar is resistant to this disease, it does occasionally occur on it. Here is more information on the Cercospora blight.

Of course, the best way to be sure if one of these is infecting your trees is to contact a professional arborist to look at them. You might also contact your St. Louis County MU Extension Center to see if they have had other reports of diseased junipers.