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Problem: Tip Dieback - Botryosphaeria sp.
Hosts: Pin oak and other red oaks
Description: Twig dieback can be caused by a fungal disease called Botryosphaeria canker. Trees affected with Botryosphaeria canker exhibit a wilting or "flagging" of twigs or small branches throughout the tree. Fully developed leaves on the twigs initially bend back towards the twig and then turn brown. The dieback extends 4-6 inches down the twig and the dead leaves remain attached. The dead twig turns black and may develop cracks. The margin between healthy and diseased bark tissue is relatively sharp. In order to see this take a knife and carefully scrape away the outer bark tissue. Healthy bark will be light green whereas diseased bark will be dark brown to black. Botryosphaeria canker is a sporadic disease on oaks. The Botryosphaeria fungus tends to cause the more damage on stressed plants.
Twig dieback rarely progresses more than a couple of inches down the twig and usually does not continue the following year.
Recommendations: Chemical controls are not recommended. Dead twigs can be removed on small trees, but otherwise don't bother.
References:
1. K-State Research and Extension Hort '97 Newsletter, September 10, 1997
Last Updated: 08/16/2004
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