Distribution, Reproduction, and Movement ofPhytophthora cinnamomion Sites Highly Conducive to Jarrah Dieback in South Western Australia

Abstract

P. cinnamomi, which causes death of Eucalyptus marginata [jarrah] and other species in the jarrah forest of south Western Australia, was recovered at a high inoculum density as deep as 75 cm in soil immediately above a concreted lateritic layer. The fungus can produce zoospores in soil at the interface of the lateritic layer. Zoospores are transmitted laterally in water flowing at the surface of the layer on sites of decline. The rapid mass decline and death of jarrah is probably a consequence of these specific site characteristics, which allow infection and destruction of the vertical root system of jarrah by P. cinnamomi.