First report of Verticillium wilt caused by Verticillium dahliae impacting Ailanthus altissima in Virginia, U.S.A.
The invasive tree of heaven, Ailanthus altissima (Miller), was first confirmed dying from Verticillium wilt (caused by both Verticillium nonalfalfae and V. dahliae) in Pennsylvania, USA, in 2002. Following this, a Virginia, USA, survey found and confirmed the reportedly more virulent V. nonalfalfae infecting A. altissima and also collected putative V. dahliae isolates, identified morphologically based on the production of brown-pigmented microsclerotia and verticillate whorls that amassed oval conidia. With increasing attention on the biological control potential of these pathogens, molecular identification (sequence analyis of ITS gene region) and Koch's postulates were done for one of these V. dahliae isolates (VdAaVA2) collected from A. altissima displaying typical Verticillium wilt symptoms (chlorotic and necrotic leaflets, severe wilt, defoliation, canopy dieback, and vascular discoloration) in Nelson County, VA, in 2009. This is thought to be the first report Verticillium wilt caused by V. dahliae impacting A. altissima in Virginia, USA.