Signs and Symptoms: A Tale of Two Tar Spots

  As noted earlier ( there are two common tar spots of maple seen in Ohio.  One, that occurs commonly on silver and red maple results in dense, tarry spots caused by the fungus, Rhytisma acerinum. A second tar spot disease is typically found on Norway maple, with multiple tiny tarry spots that eventually coalesce into a larger spot, not quite as “tarry” but nonetheless black in color, caused by the fungus  Rhytisma punctatum.



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Jim Chatfield