Phytophthora drechsleri in remote areas of southeast Alaska

Abstract

Phytophthora drechsleri was recovered from remote, undisturbed muskeg and forested sites and from one more accessible area of native vegetation in southeast Alaska. Identity of 10 isolates was confirmed by morphology and behaviour as well as electrophoretic comparison of proteins with those of known isolates. Oospores formed when Alaska isolates were mated with an A2 isolate of P. drechsleri from California. Although recovered from soils and streams in forests dominated by declining Chamaecyparis nootkatensis , the fungus was not pathogenic to this tree species in inoculation tests. Its presence in this habitat and its limited pathogenicity suggest that P. drechsleri may be indigenous to the forests of northwestern North America.