News from California and the rest of the US

Warm, wet weather caused by El Nino is a "free ticket to Disneyland" for P. ramorum in California, providing an environment in which the disease can spread:

http://www.napavalleyregister.com/lifestyles/home-and-garden/columnists/bill-pramuk/article_60416e9e-184e-11df-bfaf-001cc4c002e0.html

Researchers at University of North Carolina are developing a model to predict spread of P. ramorum if it were to get loose in the eastern US:

http://www.newsobserver.com/news/local_state/story/314528.html

NA2 lineage found on salal, additional positive nurseries

As part of the perimeter survey conducted at a P. ramorum-positive retail nursery in Pierce County, Washington last summer, the Washington State Department of Agriculture identified infested salal (Gaultheria shallon) plants in the natural landscape (as reported in the COMTF August 2009 Newsletter). Follow-up analysis of the samples by the Chastagner lab at Washington State University has resulted in the isolation of the NA2 lineage from the salal. This is the first detection of the NA2 lineage on native forest vegetation. For more information on this development, contact Gary Chastagner at chastag@wsu.edu.

Washington had two P. ramorum-positive locations identified in January. Both sites have previously been found positive for the pathogen. One positive find was in retention pond water at a Pierce County retail nursery. Treatment of the pond (located on nursery property) is optional as it is not used for irrigation or fire suppression. The second site was in a Mason County church landscape where an assumed-positive Viburnum tinus was identified as part of a Thurston County nursery trace-forward investigation. Follow-up efforts have determined that the viburnum did not transit through the Thurston County nursery, but rather was sourced from Oregon. It is unknown where the plant potentially became infested. The Oregon nursery from which the plant originated completed the CNP in December (2009). WSDA PCR results on the viburnum were inconclusive; results are pending from Beltsville, MD.

From the February COMTF newsletter

Japanese larch and Western hemlock new hosts for P. ramorum in the UK

"Since August 2009, significant numbers of Japanese larch trees have begun to show symptoms of needle loss and dieback in Devon, Cornwall and Somerset. The number of trees affected, and the apparent speed of the decline is a cause for concern – some trees are already dead. Smaller numbers of broadleaf trees associated with the larch were found to have symptoms of bleeding cankers, and closer examination by Forest Research scientists revealed that these broadleaf trees were infected with Phytophthora ramorum. This is the fungus-like pathogen responsible for the phenomenon known as “sudden oak death” in the USA, where it has killed millions of trees including the native American tanoak. "

read more here

new song - Sudden Oak Death

Listen to Sudden Oak Death - Mountain Goats & John Vanderslice on Moon Colony Bloodbath for free on Grooveshark.

http://listen.grooveshark.com/#/song/Sudden_Oak_Death/22781967

'Oak death' affects medieval site

Trees and shrubs surrounding a medieval monument in Cardiff are to be removed and burned after a plant disease which can be deadly to trees was found.
http://news.bbc.co.uk/2/hi/uk_news/wales/south_east/8377637.stm

California bans Curry County's Douglas Christmas trees

But Grand fir and Noble fir are ok?

Read the article here:
http://www.currypilot.com/20091128114288/News/Local-News/California-bans-Curry-Countys-Douglas-Christmas-trees

New article: Population genetics and migration of P. ramorum

Goss, E.M.; Larsen, M.; Chastagner, G.A.; Givens, D.R.; and Grünwald, N.J. 2009. Population genetic analysis infers migration pathways of Phytophthora ramorum in US nurseries. PLoS Pathogens 5(9): e1000583.
Abstract: 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 this pathogen from source populations on the West Coast to locations across the United States, thus risking introduction to other native forests. We examined the genetic diversity of P. ramorum in United States nurseries by microsatellite genotyping 279 isolates collected from 19 states between 2004 and 2007. Of the three known P. ramorum clonal lineages, the most common and genetically diverse lineage in the sample was NA1. Two eastward migration pathways were revealed in the clustering of NA1 isolates into two groups, one containing isolates from Connecticut, Oregon, and Washington and the other isolates from California and the remaining states. This finding is consistent with trace forward analyses conducted by the US Department of Agriculture's Animal and Plant Health Inspection Service. At the same time, genetic diversities in several states equaled those observed in California, Oregon, and Washington and two-thirds of multilocus genotypes exhibited limited geographic distributions, indicating that mutation was common during or subsequent to migration. Together, these data suggest that migration, rapid mutation, and genetic drift all play a role in structuring the genetic diversity of P. ramorum in US nurseries. This work demonstrates that fast-evolving genetic markers can be used to examine the evolutionary processes acting on recently introduced pathogens and to infer their putative migration patterns, thus showing promise for the application of forensics to plant pathogens.