@article {Hayden20111781, title = {Will all the trees fall? Variable resistance to an introduced forest disease in a highly susceptible host}, journal = {Forest Ecology and Management}, volume = {261}, number = {11}, year = {2011}, pages = {1781 - 1791}, abstract = {

Although tanoak (Notholithocarpus densiflorus syn. Lithocarpus densiflorus) is the species most affected by the introduced pathogen Phytophthora ramorum, with demonstrable risk of extirpation, little is known about the origin, range or structuring of the tree{\textquoteright}s susceptibility. We examined variation in resistance to P. ramorum using a wound inoculation assay of detached leaves from trees at five geographically separated sites, and a non-wound inoculation assay on twigs from trees at two sites. The structure of variation in resistance was compared to the structure at nine nuclear microsatellite markers. Resistance varied quantitatively, with 23\% and 12\% of the variation among individuals and populations, respectively. There was a significant correlation between resistance in detached leaves and lesion size in non-wounding twig inoculations. Among-population genetic diversity at nine microsatellite loci was weakly structured but significantly non-zero, with 9.5\% of variation among populations. Within-population neutral genetic diversity was a poor predictor of resistance, and estimates of phenotypic distances for resistance were no greater than neutral genetic distances. The limited phenotypic and genetic structure we found indicates that tanoaks at all study sites are susceptible, and there is no evidence of prior selection for disease resistance. We conclude that tanoak populations across the species{\textquoteright} range are at risk, but local disease dynamics will depend on both host genetics and environmental conditions.

}, keywords = {Sudden oak death}, issn = {0378-1127}, doi = {DOI: 10.1016/j.foreco.2011.01.042}, url = {http://www.sciencedirect.com/science/article/B6T6X-52F7TF6-1/2/55216e9ccfc0fafe0035e3d3f20ff81b}, author = {Katherine J. Hayden and Alejandro Nettel and Richard S. Dodd and Garbelotto, Matteo} } @article {4321, title = {Winter Conditions Correlate with Phytophthora alni Subspecies Distribution in Southern Sweden}, journal = {Phytopathology}, volume = {105}, year = {2015}, month = {Jan-09-2015}, pages = {1191 - 1197}, abstract = {

During the last century, the number of forest pathogen invasions has increased substantially. Environmental variables can play a crucial role in determining the establishment of invasive species. The objective of the present work was to determine the correlation between winter climatic conditions and distribution of two subspecies of the invasive forest pathogen Phytophthora alni: P. alni subspp. alni and uniformis killing black alder (Alnus glutinosa) in southern Sweden. It is known from laboratory experiments that P. alni subsp. alni is more pathogenic than P. alni subsp. uniformis, and that P. alni subsp. alni is sensitive to low temperatures and long frost periods. By studying the distribution of these two subspecies at the northern limit of the host species, we could investigate whether winter conditions can affect the geographical distribution of P. alni subsp. alni spreading northward. Sixteen major river systems of southern Sweden were systematically surveyed and isolations were performed from active cankers. The distribution of the two studied subspecies was highly correlated with winter temperature and duration of periods with heavy frost. While P. alni subsp. uniformis covered the whole range of temperatures of the host, P. alni subsp. alni was recovered in areas subjected to milder winter temperatures and shorter frost periods. Our observations suggest that winter conditions can play an important role in limiting P. alni subsp. alni establishment in cold locations, thus affecting the distribution of the different subspecies of P. alni in boreal regions.

}, keywords = {Alnus spp., invasiveness, Phytophthora plurivora}, issn = {0031-949X}, doi = {10.1094/PHYTO-01-15-0020-R}, url = {http://apsjournals.apsnet.org/doi/10.1094/PHYTO-01-15-0020-R}, author = {Redondo, Miguel A. and Boberg, Johanna and Olsson, Christer H. B. and Oliva, Jon{\`a}s} } @proceedings {960, title = {Wildland management of Phytophthora ramorum in northern California forests}, volume = {Gen. Tech. Rep. PSW-GTR-214}, year = {2008}, pages = {305-312}, publisher = {U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station}, address = {Santa Rosa, California}, url = {http://www.fs.fed.us/psw/publications/documents/psw_gtr214/}, author = {Valachovic, Y. and C. Lee and J. Marshall and H. Scanlon}, editor = {Frankel, S.J. and J.T. Kliejunas and K. M. Palmieri} }