Monday, October 12, 2009

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.

New research: Evaluating ornamentals as physical barriers between blocks of plants susceptible to Phytophthora ramorum

Shishkoff, N. 2009. Evaluating ornamentals as physical barriers between blocks of plants susceptible to Phytophthora ramorum, 2007-2008. Plant Disease Management Reports 3:OT029.

Assessing the potential of Silv-Exᆴ and Silv-Ex Plusᆴ to eradicate Phytophthora ramorum spores in water

Assessing the potential of Silv-Exᆴ and Silv-Ex Plusᆴ to eradicate Phytophthora ramorum spores in water - Based on two studies at UC Davis, using Silv-Ex® or Silv-Ex Plus® (foaming agent used in fire control) to treat water that is potentially infested with P. ramorum, greatly reduces, but does not eliminate, the concern for inadvertently spreading the pathogen through fire suppression efforts. For more information, contact Kamyar Aram at kamaram@ucdavis.edu.

Pierce county salal treated

The Washington State Department of Agriculture is working with the USDA Animal and Plant Health Inspection Service and Forest Service, as well as the State Department of Natural Resources and Pierce County, to mitigate the impacts of the previously identified P. ramorum-positive salal plants in a native landscape adjacent to a Pierce County retail nursery. The response will include remounting drainage ditches where the landscape finds were made and lining them with rock. This will prevent any future nursery runoff from coming in contact with susceptible P. ramorum hosts. The infected salal plants have been killed with herbicide, and the debris cleaned out of the ditches. For more information, contact Brad White at bwhite@agr.wa.gov.

Thursday, August 6, 2009

P. ramorum found on salal in Pierce county

From the COMTF monthly newsletter. Read more here.

A Pierce County, Washington retail nursery was found with two P. ramorum-positive Rhododendron cultivars in May and June, 2009. The nursery was also found positive in 2003 with two cultivars of Camellia, and in 2004 with 14 cultivars of Camellia and Rhododendron. Per the Confirmed Nursery Protocol, a perimeter survey was conducted and several salal (Gaultheria shallon) plants in one colony were found to be P. ramorum-positive on a bank outside the nursery on County land. Water from the infested nursery area drains into the native salal stand. APHIS is working with the County to clean up the site. APHIS is also cooperating with the Washington State Department of Agriculture, the US Forest Service, and the Washington Department of Natural Resources to further survey and bait the drainage area. This is a documented incident of P. ramorum moving out of an infested nursery and causing disease outside the nursery. For more information on Gaultheria shallon, go to the COMTF Host of the Month Archive at http://nature.berkeley.edu/comtf/html/host_of_the_month_archive.html#GaultheriaShallon. For photos and a map of salal distribution, go to the USDA Plants Profile website at http://plants.usda.gov/java/nameSearch?keywordquery=+Gaultheria+shallon+&mode=sciname.

Wednesday, July 8, 2009

Fishing for Phytophthora

Murdoch University in Western Australia officially launched a "Fishing for Phytophthora" website on 6/5 at the Dieback Information Group meeting. The website is intended to catalogue Phytophthora species found in Western Australia's rivers, streams, dams, and estuaries. Currently over 100 locations are being monitored. Website information includes a project overview, a detailed map with findings noted at each location, an interpretation of the findings, the latest news on the project, and a photo gallery. To access the website, go to: http://www.fishingforphytophthora.murdoch.edu.au/. For more information on the project, contact Daniel Hüberli at D.Huberli@murdoch.edu.au.

And if you are interested in a similar program being developed in Washington, check out our website:
http://www.puyallup.wsu.edu/ppo/sod/monitoring/stream%20monitoring.htm

New research suggests that snails and slugs may transmit P. ramorum spores

Hyder, N.; Coffey, M.D.; and Stanghellini, M.E. 2009. Viability of oomycete propagules following ingestion and excretion by fungus gnats, shore flies, and snails. Plant Disease 93:720-726.

Abstract: Sporangia of Phytophthora capsici and P. nicotianae, as well as hyphal swellings of Pythium splendens, P. sylvaticum, and P. ultimum, were ingested by adult shore flies but none were viable after passing through the digestive tract. Oospores of Pythium aphanidermatum retained their viability following ingestion by adult shore flies. Larval stages of fungus gnats and shore flies ingested sporangia of Phytophthora capsici, P. nicotianae, and P. ramorum, but they were not viable upon excretion. In contrast, hyphal swellings of Pythium
splendens, P. sylvaticum, and P. ultimum, chlamydospores of Phytophthora ramorum, and oospores of Pythium aphanidermatum, retained their viability after passage through the digestive tract of these larvae. Snails were capable of ingesting and excreting viable sporangia and chlamydospores of P. ramorum, which upon excretion infected detached leaves. Although the impact of larvae and snails in the rapid dissemination of pathogen propagules is unknown, this work does highlight the possibility that some often-ignored animal–fungus interactions should be considered in long-range dispersal of pathogen propagules via food webs.

New P. ramorum finds in Washington

A Kitsap County, WA residential landscape site was found to have
P. ramorum-positive Rhododendron Sp. 'Roseum Elegans' on 6/10/09 as part of a trace-forward investigation from an infested wholesale/production nursery in Thurston County, WA. The plant was removed and destroyed per the APHIS, PPQ "Official Regulatory Protocol for Phytophthora ramorum Detections in Landscaped Residential or Commercial Settings."

A King County, WA production nursery was confirmed to have
P. ramorum-positive Rhododendron Sp. 'Jean de Montaque' and Rhododendron Sp. 'Wojnar's Purple' on 6/23/09. The nursery was also found positive in 2006, 2007, and 2008.

From the July COMTF newsletter
http://www.suddenoakdeath.org/html/current_newsletter.html

Monday, March 30, 2009

New Clues Discovered About Divergent Origin Of Sudden Oak Death

ScienceDaily (2009-03-28) -- Sudden oak death not only causes nearly instant death to the mighty oak trees of the western United States, but also has forced many tree nurseries out of business in that region. But a new discovery about the disease pathogen's distant past--perhaps as long ago as half a million years -- may offer clues to scientists about ways to thwart the disease. ... > read full article

Monday, March 9, 2009

While UK moves to eradicate P. ramorum & kernoviae, Oregon loses steam

From an invasive species mailing list is the following news:

Dear forest pest mavens - a sad contrast between moving forward in Great Britain and very unfortunate budget-driven pulling back in Oregon.


£25M TO PROTECT PRECIOUS WOODLAND AND LANDSCAPES FROM DISEASE

The fight against a deadly plant disease plaguing historic gardens, woodland and heathlands across England and Wales received a significant boost today as UK Environment Minister Jane Kennedy announced £25 million to help eradicate the disease.

The new funding will support a five-year programme to manage and contain the risks of two plant diseases Phytophthora ramorum and Phytophthora kernoviae from spreading further, following a scientific review and stakeholder consultation.

Announcing the funding at the National Trust site at Nymans Gardens in Sussex today, Ms Kennedy said:

“These lethal diseases are having a detrimental effect in pristine locations, which in turn could have a detrimental effect on our local tourism industry, and our own lifestyles.

“Defra, the Forestry Commission and local authorities are currently tackling outbreaks across England and Wales including the New Forest, the south west of England, and Cannock Chase in Staffordshire. These are significant tourist hot spots that could face a drop in visitor numbers if we don’t act now.

“There’s nothing better than being able to escape the hustle and bustle of the city out in the fresh air in our beautiful countryside.

“But if this disease spreads, it could mean parts of the countryside being cordoned off, dogs being kept on leads, and more limited public access – in addition to further loss of our precious woodland.

“That’s why we’ve announced this significant funding to help combat these diseases and safeguard our woodlands for the future.”

The new programme is a result of an external scientific peer review and a public consultation which concluded that more should be done to try to manage the impact of the disease.

NOTES TO EDITORS:

1. Phytophthora ramorum and Phytophthora kernoviae are serious diseases of trees and shrubs, posing a threat to native woodlands and heathland species and were first detected in the UK seven years ago.

2. Since then an interdepartmental programme board has been overseeing emergency action to contain and eradicate the diseases and to coordinate research to inform decisions on future management.

3. The programme will have three main work streams:

o disease management

o education and awareness

o research and development .

4. Defra will be working with delivery bodies and key stakeholders to:

a. Build on the good work already done by stakeholder groups on codes of practice and bio-security procedures

b. plan the programme activities.

c. ensure a coordinated approach is taken

d. identify any synergies with existing work and opportunities to enhance the programme

5. The programme activity will be reviewed after three years to gauge success and plan future activity.

6. The work will be managed by a new agency FERA – the Food and Environment Research Agency. The new executive agency will bring together the expertise of the Central Science Laboratory, our Decontamination Service and Defra’s plant health and seeds directorate.

----------------

Thursday, February 26, 2009

State balances budget on ag (OR) Legislature targets natural resource agencies to balance Oregon spending

.... "Also on the block in coming days are funds for sudden oak death eradication in Southern Oregon forests. The Oregon Department of Forestry under the direction of the Legislative Fiscal Office has returned to the state $265,400 of $427,500 in general funds previously approved by the Emergency Board for SOD eradication.

According to an advisory the department issued lawmakers, the loss of those funds results in the "inability to treat newly detected infestation sites and a cessation of treatments at other sites."

I am not casting blame ... but it is unfortunate.

Faith T. Campbell

Thursday, February 26, 2009

algae control

Because Phytophthora species are close relatives of brown algae, algae control methods may be useful in reducing water infestation by Phytophthoras. Check out this tip on the WA Adopt-A-Stream website:

"Are you experiencing problems with algae in small lakes or ponds? A recent issue of Organic Gardening magazine (May/June 1999) reported that by using nylon sacks filled with barley straw can severely retard algal growth. The results have been duplicated by British researchers, but thus far, the researchers are unable to explain how and why it works. Organic Gardening recommends practitioners use three ounces of barley straw per square yard of a pond's surface for best results. Wheat straw and corn stalks are also effective, but must by applied at slightly higher concentrations. These methods are both inexpensive and more importantly, are harmless to fish."

Friday, February 6, 2009

2008 Washington nursery inspections

Washington State Department of Agriculture Plant Services Specialists inspected 320 production nurseries and 538 retail nurseries, and processed 19,965 samples for P. ramorum in 2008. Five of the nurseries inspected were placed under USDA Emergency Action Notification for the pathogen (1 landscape/wholesaler in Clark County, 1 retailer and 1 wholesaler in King County, 1 landscape/wholesaler in Snohomish County, and 1 landscape/wholesaler in Thurston County). Only one of the nurseries was a repeat positive. Since 2004, Washington has had fewer P. ramorum-positive nurseries each year.

One wholesale nursery in King County, WA, and another in Clark County, WA, each had a single PCR positive sample found during 2008 inspections; however, symptomatic plants were not found during a second inspection at either facility. Consequently, neither fell under USDA regulation due to the new Potentially Actionable Suspect Sample protocol, which requires a second positive sample be confirmed before federal action is taken. The positive blocks at both sites have been destroyed.

From COMTF February 2009 newsletter

Wednesday, February 4, 2009

Felt soled wading shoes spread water-borne diseases

Here is one more way that P. ramorum can spread into remote areas:

"Actually, it's not Baby who needs the new shoes -- it's Dad. But the old crapshooting reference is appropriate because every time we anglers travel from one trout stream to another we're rolling the dice with nature. Our wading shoes, especially the felt-soled variety, pick up tiny organisms that remain alive in the porous material and squirt free to take up residence in the next stream we fish. In this manner are some of the most pernicious, trout-threatening invasive species such as the parasite that causes whirling disease and the stream-choking algae known, not fondly, as rock snot spread from one stream to another. Extensive research has shown conclusively that felt soles have been responsible for much of the spread of whirling disease, didymo and other pest species. Now, Trout Unlimited is campaigning to make felt-soled wading shoes and boots obsolete. TU is asking the manufacturers of fishing gear to stop production of felt-soled boots and boot-foot waders by the year 2011."

See website below for complete story.

maineoutdoorjournal.mainetoday.com/blogentry.html?id=10545

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