Hispidus canker

Natural History
Hispidus canker on laurel oak
Photo credit: Dr. Jason Smith, UF/IFAS

Hispidus canker is a tree infection caused by the fungus Inonotus hispidus. This disease primarily affects water, willow and laurel oaks in Florida (though other hosts such as hickory are known). The pathogen kills the cambium and also degrades the sapwood of the host, causing sunken elongated lesions on the stems of the trees. This is known as a canker-rot pathogen. Eventually, the pathogen produces a whitish-yellow "conk," or shelf-like fruiting body. Spores are released from the conk during cool, wet weather and go on to infect new hosts – usually at wounds or pruning sites. Later, after releasing the spores, the conk dries out, becomes black, and often falls from the tree.


Identifying Characteristics

Identifying the injury: Sunken lesions (cankers) on stems. On smaller branches the symptoms may appear spindle-like. Along the margins of the cankers the callus tissue is usually evident.
Identifying the pathogen: Trees bear whitish-yellow to reddish brown, spongy, stalkless fruiting bodies (conks). After spores are released, the conks usually dry and turn blackish and often fall from the tree.
Susceptible trees: Mostly laurel, water and willow oaks. Sometimes hickory is affected.



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