Publications

aflp and phylogenetic analyses of north american and european populations of phytophthora ramorum.	the genetic structure within and between usa and european populations of the emerging phytopathogen phytophthora ramorum was examined. four primer combinations were used for amplified fragment length polymorphism (aflp) fingerprinting of 67 usa isolates from california and oregon, and 18 european isolates from belgium, germany, the netherlands, spain and the uk. in addition, three dna regions (its, cox ii, and nad 5) of additional phytophthora species were amplified by polymerase chain reaction, ...	2004	15209278
phytophthora ramorum: integrative research and management of an emerging pathogen in california and oregon forests.	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 impac ...	2005	16078887
population dynamics of the sudden oak death pathogen phytophthora ramorum in oregon from 2001 to 2004.	phytophthora ramorum (oomycetes) is an emerging plant pathogen in forests in southwestern oregon (curry county). moreover, since 2003 it has been repeatedly isolated from plants in oregon nurseries. in this study, we analysed the genetic diversity of the p. ramorum population in oregon from 2001 to 2004 by using microsatellites. a total of 323 isolates (272 from the infested forest; 51 from nurseries) were screened at 10 loci. the overall p. ramorum population in oregon is characterized by low g ...	2007	17614910
phytophthora siskiyouensis, a new species from soil, water, myrtlewood (umbellularia californica) and tanoak (lithocarpus densiflorus) in southwestern oregon.	an unknown phytophthora species was recovered in southwestern oregon from rhododendron and tanoak leaf baits used for monitoring streams and soils for the presence of phytophthora ramorum, from a blighted shoot of myrtlewood and from tanoak bark cankers. isolates of this species yielded its-dna sequences that differed substantially from other phytophthora sequences in genbank. morphological features also differed from available descriptions of known phytophthora species. based on the combination ...	2007	18268898
mitochondrial haplotype determination in the oomycete plant pathogen phytophthora ramorum.	the mitochondrial genome of an isolate of phytophthora ramorum from europe (eu) was sequenced and compared to the previously published genome sequence of an isolate from california (na). the eu mitochondrial genome had the identical gene order and encoded for the same suite of genes as the na mitochondrial genome, but had 13 single nucleotide polymorphisms (snps) and at 39,494 bp was 180 bp longer. this length difference was due to an increase in the size of the spacer region between the nad5 an ...	2008	18488228
aflps detect low genetic diversity for phytophthora nemorosa and p. pseudosyringae in the us and europe.	in california and oregon, two recently described oomycete forest pathogens, phytophthora nemorosa and p. pseudosyringae, overlap in their host and geographic ranges with the virulent p. ramorum, causal agent of "sudden oak death." epidemiological observations, namely broader geographic distribution and lack of landscape-level mortality, led to the hypothesis they are native to this region, whereas multiple lines of evidence indicate p. ramorum is exotic to north america. we used aflp analysis to ...	2009	19061958
migration patterns of the emerging plant pathogen phytophthora ramorum on the west coast of the united states of america.	phytophthora ramorum (oomycetes) is the causal agent of sudden oak death and ramorum blight on trees, shrubs, and woody ornamentals in the forests of coastal california and southwestern oregon and in nurseries of california, oregon, and washington. in this study, we investigated the genetic structure of p. ramorum on the west coast of the united states, focusing particularly on population differentiation potentially indicative of gene flow. in total, 576 isolates recovered from 2001 to 2005 were ...	2009	19453234
population genetic analysis infers migration pathways of phytophthora ramorum in us nurseries.	recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. however, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in california forests and ramorum blight of common ornamentals. the nursery trade has moved thi ...	2009	19774068
effects of an invasive forest pathogen on abundance of ticks and their vertebrate hosts in a california lyme disease focus.	invasive species, including pathogens, can have important effects on local ecosystems, including indirect consequences on native species. this study focuses on the effects of an invasive plant pathogen on a vertebrate community and ixodes pacificus, the vector of the lyme disease pathogen (borrelia burgdorferi) in california. phytophthora ramorum, the causative agent of sudden oak death, is a non-native pathogen killing trees in california and oregon. we conducted a multi-year study using a grad ...	2010	20941513
temporal epidemiology of sudden oak death in oregon.	an effort to eradicate phytophthora ramorum, causal agent of sudden oak death, has been underway since its discovery in oregon forests. using an information-theoretical approach, we sought to model yearly variation in the size of newly infested areas and dispersal distance. maximum dispersal distances were best modeled by spring and winter precipitation 2 years before detection, and infestation size the year prior. infestation size was best modeled by infestation size and spring precipitation th ...	2015	25871855
spatial and temporal analysis of populations of the sudden oak death pathogen in oregon forests.	sudden oak death caused by the oomycete phytophthora ramorum was first discovered in california toward the end of the 20th century and subsequently emerged on tanoak forests in oregon before its first detection in 2001 by aerial surveys. the oregon department of forestry has since monitored the epidemic and sampled symptomatic tanoak trees from 2001 to the present. populations sampled over this period were genotyped using microsatellites and studied to infer the population genetic history. to da ...	2015	26068281