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W. Sorgen
W. Sorgen, ISA Ceritified Arborist
Category: Landscaping
Satisfied Customers: 178
Experience:  Bachelor's degree in forestry, and owner of a residential/commercial tree service.
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One of my black oak trees is weeping a black tar substance

Customer Question

One of my black oak trees is weeping a black tar substance from the trunk bark. It is not sticky. What is it?
Submitted: 1 year ago.
Category: Landscaping
Expert:  W. Sorgen replied 1 year ago.
It could be a couple of different things; a picture would be helpful. If it's coming from the bottom of a narrow crotch, it's usually associated with a bacterial infection called wetwood or slime flux. If it's just coming out of the bark in random places, it's likely phytopthera (a fungus).