Colonization by Armillaria mellea and Agrilus bilineatus of oaks injected with ethanol [Quercus velutina, and white oaks, Quercus alba]

Roots of undefoliated black oaks, Quercus velutina , and white oaks, Q. alba , were injected with water or ethanol (5, 20, or 50 percent) to determine if ethanol, which may occur in roots of defoliated trees, could induce invasion by Agrilus bilineatus and/or Armillaria mellea - two secondary invaders commonly associated with mortality of defoliated trees. Trees of both species injected with 50 percent ethanol experienced greater attack by A. bilineatus and had more tissue necrosis up the stem than trees in the other treatments. A. mellea colonized roots of both oak species that were injected with 20 or 50 percent ethanol, and colonization was greater in trees injected with 50 percent ethanol. These trees also were severely attacked by A. bilineatus , exhibited dieback 1 year after injection, and showed premature autumn color.