Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #155098
Title: FIRST REPORT OF PHYTOPHTHORA RAMORUM BLIGHT ON PIERIS, RHODODENDRON, VIBURNUM, AND CAMELLIA IN OREGON NURSERIES

Author
item PARKE, J.L. - OSU
item Linderman, Robert
item OSTERBAUER, N.K. - ODA, SALEM OR
item GRIESBACH, J.A. - ODA, SALEM OR

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2003
Publication Date: 1/1/2004
Citation: Parke J.L., Linderman, R.G., Osterbauer, N.K., Griesbach, J.A. First Report Of Phytophthora Ramorum Blight On Pieris, Rhododendron, Viburnum, And Camellia In Oregon Nurseries. Plant Disease. 2004. v88 p.87

Interpretive Summary: Interpretive Summary: 'Detection of Phytophthora ramorum Blight in Oregon Nurseries and Completion of Koch's Postulates on Pieris, Rhododendron, Viburnum, and Camellia' by J. L. Parke, R. G. Linderman, N. K. Osterbauer, and J. A. Griebach The Sudden Oak Death (SOD) disease of oaks and other plant species in California and Oregon, caused by Phytophthora ramorum, also affects many nursery crops as well. In Europe, P. ramorum had only been found causing disease on rhododendrons and viburnums and some other nursery crops, but recently was found on oaks growing near affected rhododendrons. The Oregon Department of Agriculture has maintained a high level of alert for this pathogen in Oregon nurseries, and recently detected it on several host plant species in several wholesale and retail nurseries. This report indicates the results of isolations from infected plants, identification by cultural and PCR methods, and inoculations performed to prove the pathogenicity of isolates of the pathogen from each host species and cultivar on the source host, namely cultivars of Pieris, Rhododendron, Viburnum, and Camellia. Based on these results, these hosts will be added to the official list of regulated hosts in the U.S., and this report will alert inspectors and nurserymen of the potential for these plants to be infected by P. ramorum.

Technical Abstract: Phytophthora ramorum, the cause of the Sudden Oak Death syndrome in California and Oregon and shoot blight and leaf spot of many landscape plant species in Europe, was detected in wholesale and retail nurseries in Oregon for the first time. The pathogen was isolated and identified by means of cultural characteristics and PCR from infected plants of Pieris, Rhododendron, Viburnum, and Camellia. The pathogen was determined to be mainly the A1 mating type and the European genotype. Koch's Postulates were satisfied to prove pathogenicity on specific host cultivars using isolates from those same hosts.