What caused the spotting on this maple leaf? And for extra credit, what species of maple tree produced this leaf?
Answer
Called “tar spot,” this marking is caused by fungi in the genus Rhytisma. The spotting generally does not harm trees, and it can affect various maple species. This leaf is from a Norway maple. For more information about tar sport, check out this October 2020 This Week in the Woods entry in our archives.
This week’s contest winner was Molly Hale