Verticillium wilt is a destructive disease which can kill a mature maple tree within a few weeks. This fungal disease most often attacks ash and maple trees. It can also afflict a number of other tree species and flowering shrubs including cherry, lilac, viburnum, and smokebush. The fungus enters and takes up residence in the xylem of the tree and blocks the movement of water and sap. Verticilium fungus lives in the soil and enters the tree through damaged roots. Typically fatal, it is possible to extend the life of affected trees with intervention.
Symptoms: In the early stage wilting and yellowing of leaves and branches will be evident. The wilted branches may have streaks of dark green under the bark called vascular streaking.
More information: University of Wisconsin Madison Extension, Iowa State University Extension and Outreach, Michigan State University Extension
Photo: University of Maryland / Michigan State University