Symptoms of EFB

John Pinkerton, Ken Johnson, Jay W. Pscheidt

The stromata are at first white when they break through the surface and turn black by August. Stromata usually are arranged in single or double rows along the stem. Death of the cambium in the area of the canker results in a sunken appearance as the surrounding cambium continues to grow.

One of these black stroma may contain 50 to 100 flask-shaped perithcia. Each perithecium may contain 1,000 sacks or asci, each of which contains 8 ascospores. The ascospores reach maturity by the time fall rains begin in October.

The disease may be confused with Eutypella cerviculata, which produces smaller black fruiting bodies on dead branches. This fungus produces diagnostic black rings under the bark, which can be detected using a pocketknife. Cicada-egg-laying scars can also look somewhat like EFB but are not black and look stitched.

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Mature, black stromata arranged in rows along an older branch. Note the dead twig near the center of the canker. This is the shoot that the fungus originally infected several years earlier..
Photo by Jay Pscheidt, 1988.
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Another EFB look-alike is the ovaposition wounds produced by cicada insects when laying eggs.
Photo by Jay Pscheidt, 1995.
 

 

 

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