@article {doi:10.1094/PD-89-0063, title = {Susceptibility of Oregon forest trees and shrubs to Phytophthora ramorum: a comparison of artificial inoculation and natural infection}, journal = {Plant Disease}, volume = {89}, number = {1}, year = {2005}, pages = {63-70}, abstract = {

Phytophthora ramorum is an invasive pathogen in some mixed-hardwood forests in California and southwestern Oregon, where it causes sudden oak death (SOD) on some members of Fagaceae, ramorum shoot dieback on some members of Ericaceae and conifers, and ramorum leaf blight on diverse hosts. We compared symptoms of P. ramorum infection resulting from four different artificial inoculation techniques with the symptoms of natural infection on 49 western forest trees and shrubs; 80\% proved susceptible to one degree or another. No single inoculation method predicted the full range of symptoms observed in the field, but whole plant dip came closest. Detached-leaf-dip inoculation provided a rapid assay and permitted a reasonable assessment of susceptibility to leaf blight. Both leaf age and inoculum dose affected detached-leaf assays. SOD and dieback hosts often developed limited leaf symptoms, although the pattern of midrib and petiole necrosis was distinctive. Stem-wound inoculation of seedlings correlated with field symptoms for several hosts. The results suggested that additional conifer species may be damaged in the field. Log inoculation provided a realistic test of susceptibility to SOD, but was cumbersome and subject to seasonal variability. Pacific rhododendron, salmonberry, cascara, and poison oak were confirmed as hosts by completing Koch{\textquoteright}s postulates. Douglas-fir was most susceptible to shoot dieback shortly after budburst, with infection occurring at the bud.

}, doi = {10.1094/PD-89-0063}, url = {http://apsjournals.apsnet.org/doi/abs/10.1094/PD-89-0063}, author = {Hansen, E.M. and Parke, J. L. and Sutton, W.} } @article {657, title = {Survival, spread, and pathogenicity of Phytophthora spp. on Douglas-fir seedlings planted on forest sites.}, journal = {Phytopathology 70:}, volume = {70}, year = {1980}, pages = {422-425}, abstract = {

Douglas-fir seedling stock infected in the nursery with Phytophthora cryptogea, P. drechsleri, P. megasperma, P. cactorum, and an unidentified Phytophthora sp. were outplanted on commercial forest sites to test survival of the diseased trees and of the pathogens. Mortality of trees initially classified in severe, moderate, and inconspicuous symptom classes at outplanting reached 61, 26, and 11\%, respectively, after 18 mo. Phytophthora was recovered about equally from roots of trees in each symptom class (15, 13, and 12\%). Surviving trees regenerated healthy roots above old lesions even though Phytophthora persisted. Disease spread was limited. None of 360 healthy trees planted 0.6 m downslope from diseased trees became infected, and only 2 of 720 healthy trees became infected after each was paired with a diseased tree in the same planting hole.

}, doi = {10.1094/Phyto-70-422}, url = {http://www.apsnet.org/publications/phytopathology/backissues/Documents/1980Abstracts/Phyto70_422.htm}, author = {Hansen, E.M. and L.F. Roth and P.B. Hamm and A. J. Julis.} } @article {361, title = {Species of the Phytophthora megasperma complex}, journal = {Mycologia,}, volume = {83}, year = {1991}, month = {May - Jun., 1991}, pages = {376-381}, issn = {00275514}, url = {http://www.jstor.org/stable/3759999}, author = {Hansen, E.M. and D. P. Maxwell} } @article {hansen1996survival, title = {Survival of Phytophthora lateralis in infected roots of Port Orford cedar}, journal = {Plant Disease}, volume = {80}, number = {9}, year = {1996}, pages = {1075{\textendash}1078}, publisher = {[St. Paul, Minn.: American Phytopathological Society], 1980-}, issn = {0191-2917}, author = {Hansen, E.M. and P.B. Hamm} }