White spots on my maple trees #613720 - Ask Extension

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White spots on my maple trees #613720

Asked February 17, 2020, 2:44 PM EST

This winter I noticed white sports on the bark of my Maple Trees. Three different kinds of Maple Trees. I had read it could be a kind of wasp that can eventually kill the trees. Please help

Scott County Minnesota

Expert Response

This appears to be White spot lichen phylctis argena which is usually not harming your tree. This tends to grow on older trees and shrubs.
http://www.florafinder.com/Species/Phlyctis_argena.php
To my eye, this tree looks like it may need some pruning (not for the white spots but because of the dense systems of branches.  
A certified arborist could advise you on pruning and the spots.  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional
Thank you for writing.
Steve Miles Replied February 22, 2020, 12:08 PM EST

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