Two nurseries positive for P. ramorum in May

Washington was found to have two P. ramorum-positive nurseries in May. (1) On 5/3 a Thurston County wholesale/production nursery was found to have P. ramorum-positive Mahonia nervosa and Viburnum tinus as a result of a nursery compliance inspection. This nursery ships interstate and was previously positive for P. ramorum in 2008. Trace-forward and -back investigations are underway. (2) A Snohomish County wholesale nursery was determined to have P. ramorum-positive Rhododendron sp. on 5/6 as a result of a nursery compliance inspection. This nursery ships interstate and was previously positive for P. ramorum in 2008. Trace-forward and -back investigations are underway.

A Tale of Three Nurseries

A heartwarming (or frightening) tale of three nurseries, reposted from the Oregon Invasive Species blog:

Once upon a time there were three nurseries. As long as people could remember, these nurseries had been growing and selling plants to satisfied customers. The nurseries were called: Clean and Green, Pretty Good Plants, and Cuttin Corners....

read the whole story here:
http://oregoninvasivespecies.blogspot.com/2010/06/tale-of-three-nurseries.html

SOD found in South Wales on larch

Forestry Commission experts are working to contain the spread of Phytophthora ramorum infection to Japanese larch trees in South Wales.

Phytophthora ramorum (P. ramorum) is a fungus-like pathogen that kills many of the trees and plants that it infects. Japanese larch trees infected by P. ramorum were first found in South West England last year, the only place in the world where it has attacked large numbers of a commercially grown species of conifer tree.

This development was a step change in the pathogen’s behaviour. Since first being identified in Britain in 2002, on a viburnum plant in a garden centre, it had affected mostly shrub and ground-cover plants such as rhododendron, viburnum and bilberry. Fewer than 100 infected trees – mostly beech - had been found, and most of those were standing close to infected rhododendron bushes.

Although it has been confirmed in only one area of larch forest in Wales so far, Forestry Commission Wales expects to find more as ground inspections follow up the aerial surveys that have pinpointed suspect areas of woodland. Scientists at the Commission’s Forest Research arm believe it likely that the spores that spread the disease have been spread to the larch forests in rain, mists and air currents carried across the Bristol Channel from the South-west, where it was confirmed in Japanese larch last September.

Roddie Burgess, Head of the Forestry Commission’s Plant Health Service, said the Commission and its partners are taking the development very seriously, but hope to be able to contain it.

Read the complete article here:

http://www.forestry.gov.uk/newsrele.nsf/AllByUNID/11FB60906B36B2C68025773D005CD276

How pathogens can survive in aquatic environments

This article may give some insights into how P. ramorum can persist in a stream environment:

Islands of Germs: Researchers Discover Pathogens Floating on Tiny Clumps of Aquatic Detritus

Researchers have found evidence that "marine snow"--aggregates of organic material floating in water bodies--may act as microscopic, island-like refuges for pathogens, or disease-causing organisms. This detritus may skew water sampling procedures and mathematical models used to predict the transmission of waterborne diseases to humans.

(follow the link above to read the whole article)

WSU stream monitoring program

The Washington State University, Puyallup (WSU-P) SOD community-based stream monitoring program was piloted in March 2010 in Washington's Puget Sound region. In addition to increasing the number of streams monitored for P. ramorum throughout the state by the Washington State Department of Agriculture (WSDA) and Washington Department of Natural Resources (WADNR), the new program also has potential to increase community awareness about the spread of P. ramorum and other Phytophthoras in streams. WSU-P received two years worth of funding from the USDA Forest Service to manage this program, which involves Master Gardeners, high school and college students, and other volunteers. Baiting sites were chosen based on discussions with WSDA and WADNR, and also volunteer availability. In 2010 four sites are being monitored for six two-week intervals and three sites for one two-week interval. The two-week interval sites are part of class projects for UW-Tacoma and Pierce College. Some students are also doing projects in the lab related to disinfectant use and survival in saline conditions. The program will be expanded in 2011. No P. ramorum has been detected at any of the sites so far. For more information, go to http://www.puyallup.wsu.edu/ppo/sod/monitoring/stream%20monitoring.htm or contact Marianne Elliott at melliott2@wsu.edu.

From the May COMTF newsletter

WSDA survey results

The Washington State Department of Agriculture (WSDA) has surveyed 30 host and non-host nurseries to date this year for P. ramorum, all of which have been negative for the pathogen. Some shippers in the state have greatly reduced the amount of high-risk genera (Camellia, Rhododendron, Pieris, Viburnum, and Kalmia) inventory for sale in an effort to reduce the risk of a P. ramorum find. However, two nurseries continue to yield positive water samples - one in Pierce County and one in King County. These sites continue to be monitored as no infected plants have been found in association with the positive water and the inoculum source is unknown. February and April surveys of plants downstream from the Pierce County positive nursery perimeter salal find in 2009 found no positive plants, and the Rosedale Stream has been continuously baited since January 2010, with no positive water finds. WSDA also followed up on trace-forward investigations from a Pennsylvania positive nursery, of which all 160 Laurus nobilis imported plants were free of P. ramorum.

From the May COMTF newsletter

A new invasive species on the landscape

Not a Phytophthora, but still -beware!

Gnome Management in the Garden