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.

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.

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