ARS | Publication request: SUSCEPTIBILITY OF CAMELLIA TO PHYTOPHTHORA RAMORUM, THE "SUDDEN OAK DEATH" ORGANISM

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 28, 2005
Publication Date: March 20, 2006
Citation: Shishkoff, N. 2006. Susceptibility of camellia to phytophthora ramorum, the "sudden oak death" organism. Plant Health Progress. DOI=10.1094/PHP-2006-03S-01-RS

Interpretive Summary: Phytophthora ramorum causes leaf spots, twig blight, and cankers on a number of plant hosts. It was first observed in California forests and on nursery stock in Europe in the mid-1990's. In 2003, camellias infected with P. ramorum were found in California nurseries. In 2003-2004, camellia plants from a large wholesale nursery, some of which were infected with P. ramorum, were sold to nurseries in 39 states triggering nationwide concern about the movement of the organism. Given the importance of camellia to the nursery industry, it became necessary to understand the symptomology and relative susceptibility of members of the genus Camellia to P. ramorum. This paper describes the symptoms on camellia and the relative susceptibility of a number of species and cultivars.

Technical Abstract: Camellia is known to be infected by Phytophthora ramorum, the 'sudden oak death' organism and in 2003-2004 the organism moved out of California on infected nursery stock, leading to a nationwide effort to recover the infected plants. Initially, only one cultivar was found to be infected (C. sasanqua 'Bonanza'), but soon it became apparent that many cultivars were susceptible. This paper describes the symptoms on camellia and the relative susceptibility of a number of species and cultivars. Camellias differ widely in susceptibility, and one of the main symptoms of infection is defoliation. There is interest among growers in using resistant cultivars to reduce the risk of outbreaks of the disease.