Poster Sessions Concurrent Sessions Conference Proceedings Oak Symposium Home This poster was not included in the Symposium Proceedings.	Pre-Symposium Poster Abstract Interaction of Sudden Oak Death Phytophthora with Associated Organisms Pavel Svihra University of California Cooperative Extension, 1682 Novato Blvd., Suite150B, Novato, CA 94947, (415) 499-4204, pxsvihra@ucdavis.edu Sudden Oak Death is a new disease that has killed large numbers of oaks (Quercus agrifolia, Quercus kelloggii, Quercus parvula var. shrevei) and tanoaks (Lithocarpus densiflorus) in some of central California's coastal counties. The name Sudden Oak Death is used because of the rapid color change of leaves from green to brown, but the entire sequence of events is not sudden . In June 2000 an unknown species of Phytophthora sp. was discovered as the underlying cause of Sudden Oak Death, which was later identified as a new species, Phytophthora ramorum. A tree may be infected with P. ramorum for a number of months before exhibiting this sudden change in foliage. After the infection begins, attacks by oak bark beetles, Pseudopityophthorus pubipennis, and oak ambrosia beetles, Monarthrum scutellare, and the growth of Hypoxylon thouarsianum also occur, which appear to contribute to hastening the tree's eventual death. The time between inoculation of these trees by Phytophthora ramorum and appearance of symptoms on the bark and foliage may take weeks or months (incubation period). While the incubation period cannot be seen, the above presented sequences clearly show that Sudden Oak Death actually requires one or more growing seasons until the tree dies.
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