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Saturday - May 15, 2010

From: Corsicana, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Orange patches circling cedar branches
Answered by: Nan Hampton and Eric Beckers

QUESTION:

We have dry rusty orange patches that circle several of our Cedar branches. There are a few orange blobs on different limbs, but they do not look like the pictures of Cedar Rust (no horns). The foliage is turning orange on these trees, as well. Do you know what this could be? Also, is Oak Wilt limited to certain areas, or are Oaks at risk in all areas of Texas?

ANSWER:

You may have stumped us! First of all, we aren't sure which cedar you might have.  Is it Juniperus ashei (Ashe's juniper) or Juniperus virginiana (eastern redcedar)?  Actually, that probably doesn't really matter because any juniper disease would most likely affect either one.  I spent a good bit of time looking for a likely candidate for your cedar infestation with no success.  I then passed the problem on to Eric Beckers of the Texas Forest Service and he confirmed that, if it's not cedar apple rust, this is a tough one.  He says that if the gall has dried up it won't show the "horns" or bright orange soft tendrils.  He suggested that you send us photos of the orange blobs and the the dying needles on the tree. Please visit Mr. Smarty Plants' Plant Identification page to read instructions for submitting photos.

There are several species of the fungus (Gymnosporangium sp.) that cause cedar rust.  You can see images of some of these at the Forestry Images site from the USDA Forest Service (scroll down the page to find Gymnosporangium).  The Plant Clinic site from Cornell University also has good images as well as some management strategies.

Now for the oak wilt part of your question, you can see maps showing the occurrence of oak wilt in Texas on the Texas Oak Wilt Information Partnership page.  The majority of the occurrences are in the central part of Texas from just below the Red River at the Oklahoma border to a line north of a Wimberley to Kyle line.  There are some scattered occurrences in west Texas.  Unfortunately, Navarro County is shown adjacent to counties that show oak wilt on these maps that are several years old.

 

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