COMPARATIVE SUSCEPTIBILITY OF WOODY UNDERSTORY PLANTS TO PHYTOPHTHORA RAMORUM, THE CAUSAL AGENT OF SUDDEN OAK DEATH

Abstract

Phytophthora ramorum, Taxonomic position: Stramenopila; Oomycota; Oomycetes; Pythiales; Pythiaceae; Phytophthora ramorum (S.Werres, A.W.A.M. de Cock & W.A. Man in't Veld) is a newly introduced plant pathogen that is of concern in the United States and Europe. The pathogen has been implicated in the death of oaks on the U.S. west coast and causes leaf blight and stem dieback in many plants. Five species of eastern native understory plants were assayed for susceptibility to P. ramorum under laboratory conditions. Rhododendron 'Cunningham's White' is known to be a highly susceptible host and was used as a positive control. Lindera benzoin (spice bush), Lonicera japonica (Japanese honeysuckle), and Vitis vulpina (wild grape). developed moderate and low-level foliar infections. Phytophthora ramorum could not be recovered from Parthenocissus quinquefolia (Virginia creeper) after inoculation.