Watch Out for Oak Wilt

In 2016 oak wilt was found at new locations in Islip, Riverhead, Southhold, Brooklyn and Canandaigua in addition to a known location in Glenville, New York. Since so many new locations surrounding our region were discovered last year, it is important that we are all aware of what the signs of this disease are and that any new locations are discovered quickly and reported.

Oak wilt (Ceratocysis fagacearum) is a fungus that infects the conductive tissue (water carrying cells) of oak trees.  The fungus blocks the flow of water and nutrients from the roots to the crown of the tree. Susceptibility depends on the species of oak.  Species in the red oak group may die within 1-5 weeks, while species in the white oak group may persist for years. In red oaks, fungal spores can be transported through all parts of the tree as the tree nears death; but in white oaks the distribution of spores only occur in the xylem of the current year’s growth.

Oak wilt was first discovered in Wisconsin in 1944 and has spread through the Midwest from Minnesota to Texas.  It was first found in New York State in 2008 at the Glenville site.  

Symptoms of oak wilt include browning of the leaves from the tip and edges moving in towards the midrib of the leaf.  Trees will shed leaves in late spring to early summer.  Infected red oaks lose their leaves from the top down, while in the white oak group leaves are lost in sections.