Florida Forest Diseases
Hispidus canker
Hispidus canker is 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) and causes sunken elongated lesions on the stems of oak trees. The pathogen kills the cambium and also degrades the sapwood of the host. This is known as a canker-rot pathogen. Eventually, the pathogen produces a whitish-yellow “conk” – or shelf-like fruiting body that becomes black after it dries and often falls from the tree. Spores are released during cooler, wet weather and infect new hosts – usually at wounds or pruning sites. |
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Identifying Characteristics |
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Identifying the injury: |
Sunken lesions (cankers) on stems. On smaller branches the symptoms may appear spindle-like. Along the margins of the cankers callus tissue is usually evident. |
Identifying the pathogen: |
Whitish-yellow to reddish brown, spongy, stalkless fruiting bodies. The conks usually turn blackish and dry after spores are released and often fall from the tree. |
Susceptible trees: |
Mostly laurel, water and willow oaks. Sometimes hickory is affected. |
Photos |
Fresh fruiting bodies of I. hispidus on oak
Photo credit: Bugwood.org
Canker and fruiting body on oak
Photo credit: Bugwood.org