01227nas a2200145 4500008004100000245011900041210006900160300000800229490000700237520074000244100001500984700001800999700001601017856004801033 2005 eng d00aPhytophthora ramorum: integrative research and management of an emerging pathogen in California and Oregon forests0 aPhytophthora ramorum integrative research and management of an e a3090 v433 a

Phytophthora ramorum, causal agent of sudden oak death, is an emerging plant pathogen first observed in North America associated with mortality of tanoak (Lithocarpus densiflorus) and coast live oak (Quercus agrifolia) in coastal forests of California during the mid-1990s. The pathogen is now known to occur in North America and Europe and have a host range of over 40 plant genera. Sudden oak death has become an example of unintended linkages between the horticultural industry and potential impacts on forest ecosystems. This paper examines the biology and ecology of P. ramorum in California and Oregon forests as well discussing research on the pathogen in a broader management context.

1 aRizzo, D M1 aGarbelotto, M1 aHansen, E M uhttp://www.annualreviews.org/toc/phyto/43/101926nas a2200169 4500008004100000245011900041210006900160300001200229490000700241520135400248100001501602700001801617700001801635700001901653700001501672856006901687 2002 eng d00aPhytophthora ramorum as the cause of extensive mortality of Quercus spp. and Lithocarpus densiflorus in California0 aPhytophthora ramorum as the cause of extensive mortality of Quer a205-2140 v863 a

A new canker disease, commonly known as sudden oak death, of Lithocarpus densiflorus, Quercus agrifolia, Q. kelloggii, and Q. parvula var. shrevei in California is shown to be caused by Phytophthora ramorum. The pathogen is a recently described species that previously was known only from Germany and the Netherlands on Rhododendron spp. and a Viburnum sp. This disease has reached epidemic proportions in forests along approximately 300 km of the central coast of California. The most consistent and diagnostic symptoms on trees are cankers that develop before foliage symptoms become evident. Cankers have brown or black discolored outer bark and seep dark red sap. Cankers occur on the trunk at the root crown up to 20 m above the ground, but do not enlarge below the soil line into the roots. Individual cankers are delimited by thin black lines in the inner bark and can be over 2 m in length. In L. densiflorus saplings, P. ramorum was isolated from branches as small as 5 mm in diameter. L. densiflorus and Q. agrifolia were inoculated with P. ramorum in the field and greenhouse, and symptoms similar to those of naturally infected trees developed. The pathogen was reisolated from the inoculated plants, which confirmed pathogenicity.

1 aRizzo, D M1 aGarbelotto, M1 aDavidson, J M1 aSlaughter, G W1 aKoike, S T uhttp://apsjournals.apsnet.org/doi/abs/10.1094/PDIS.2002.86.3.205