Phytophthora leaf blight - a new disease of California wax-myrtle (Morella californica) in Oregon, USA caused by a Phytophthora species

Publication Type:

Journal Article


N. Z. J. For. Sci., Volume 41 Suppl., p.S57-S63 (2011)


In spring, 2009, the Oregon State University Plant Clinic received reports of severe defoliation of California wax-myrtle plants (Morella californica (Cham. & Schlecht.) Wilbur) on the north-central coast of Oregon, in western North America. Isolations from necrotic leaf tissue yielded an organism which, from morphological characteristics and a genus-specific enzyme-linked immunosorbent assay, was identified as a species of the genus Phytophthora. Total DNA was extracted from hyphal tip-derived cultures from leaf or twig tissue and subjected to a polymerase chain reaction process aimed at species identification. Sequencing techniques revealed a 99.7% match with P. syringae although our isolates differed from published descriptions of this species in some respects. Inoculation of healthy plants with cultured mycelium resulted in symptoms similar to those originally observed in the field, and reisolations produced colonies of the same organism. This is the first report of a species of Phytophthora causing disease in M. californica. Leaf blight of California wax-myrtle is now widespread on the north-central coast of Oregon. This disease is serious and is adversely affecting the health of this native understory species which is frequently used for amenity plantings.