Phytophthora siskiyouensis

Abstract

Phytophthora siskiyouensis Reeser & E.M. Hansen (2007) was discovered first in streams and soil in Curry County, Oregon in areas dominated by native forest, and most isolates continue to come from these sources. Only later, and still infrequently, were isolates of the new species recovered from diseased forest plants. Recent reports that the same fungus was killing alders planted in cities in California (Rooney-Latham et al. 2007)and Australia (Smith et al. 2006) were a surprise. Phytophthora siskiyouensis appears to be part of the native forest mycoflora of SW Oregon, causing occasional symptoms on a variety of associated plants, including bole cankers on tanoaks. Its appearance as an aggressive pathogen of alder in urban settings (Rooney-Latham et al. 2007, Smith et al. 2006), however, suggests that it has a larger distribution and greater pathogenic potential than has been observed in Oregon. Red alder trees of all ages grow on the sites and adjacent to the streams that yielded P. siskiyouensis in Oregon, but careful examination and isolations yielded no Phytophthora. Etymology: "siskiyouensis" refers to the Siskiyou Mountains in SW Oregon where the new species was first identified.

Citation

Hansen, E. M.; Reeser, P.; Rooney-Latham, S. 2011. Phytophthora siskiyouensis. Forest Phytophthoras. 1(1). 4 p. [early view] doi: 10.5399/osu/fp.1.1.1826