Treesearch

Oregon was a participant in the pilot test of the national stream monitoring protocol for SOD. We routinely and continuously monitor about 50 streams in and near the SOD quarantine area in southwest Oregon using foliage baits. For the national protocol, we added six additional streams beyond the area of known infestation, and compared results from different diagnostic tests with results from six streams within the quarantine area. Foliage baits were in streams for two weeks, then assayed by: 1) culture on selective medium; 2) PCR diagnosis using the P. lat multiplex primers; 3) nested PCR...

The tanoak (Lithocarpus densiflorus) stands of California?s central coast have suffered high mortality rates due to infection by Phytophthora ramorum. Treatment programs were put in place to test the efficacy of phosphonate compounds in real world situations, to preserve some germplasm and ecosystem elements for future research, and to help mitigate the buildup of standing fuels for local homeowners. Two approaches were involved, one using experimental plots distributed over a range from Marin County to Monterey County, and another involving a cooperative treatment arrangement with Big Sur...

Phytophthora ramorum is a pathogen of regulatory concern in North America and Europe. In 2004, potentially infected plants were shipped from large, wholesale nurseries on the West Coast (California, Oregon, and Washington) throughout the U.S. This prompted a nationwide survey effort and the adoption of a federal order requiring mandatory inspection and testing of all West Coast nurseries shipping P. ramorum host and associated host plants (HAP) interstate. In Oregon, this required the testing of 51,645 samples from 1,034 growing areas and 79,930 samples from 1,394 growing areas in 2005 and...

Chlamydospores are a distinctive feature of Phytophthora ramorum. They are formed quickly in agar, and within colonized leaves. We followed their development and maturation in vitro and in vivo, and studied conditions affecting their germination. Cell walls of mature P. ramorum chlamydospores are thicker than reported for other Phytophthora species, although thin-walled chlamydospores are also formed. Chlamydospores formed within rhododendron leaves are smaller with thicker walls than spores formed in vitro. Chlamydospore development begins on hyphae less than two days old, and chlamydospor...

We monitored Ericaceous habitat in Georgia and South Carolina for temperature, dew point and humidity ranges throughout a two year period. Temperature and humidity data were used to characterize their range in Georgia and South Carolina where potential SOD susceptible hosts occur. This data suggests risk for SOD development may be more widespread in southeastern forest microclimates than current risk maps indicate. A sudden oak death infection risk index based on laboratory infection parameters for Phytophthora ramorum was developed for use in the field. In addition, we monitored streams...

The remaining native flora of Hawaii are under continuing pressure from habitat loss and exotic, invasive organisms, including animals, plants, and pathogens. In order to assess the risk to P. ramorum, we inoculated seedlings of Metrosideros polymorpha (ohia), Vaccinium calycinum (ohelo), Acacia koa (koa), and Leptecophylla tameiameiae (pukiawe) with the pathogen. Two isolates were used, one from an Oregon horticultural nursery, and one from tanoak in the Oregon infested forest area. A zoospore suspension was sprayed on the intact plants. Plants were inspected periodically and symptomatic...

Three silvicultural treatment study sites are being established to examine the effects of thinning and prescribed burning on infection and spread of Phytophthora ramorum. Study sites are located in Mendocino and Santa Cruz counties, California. Stands are even-aged redwood/tanoak mixtures.

This paper provides a brief survey of contemporary central and northwest California Indian uses for food of regulated hosts and associated species affected by Phytophthora ramorum, including recipes from Karuk/Shasta/Abenake elder Josephine Peters. It contextualizes these food uses in terms of their on-going significance in cultural, social and community contexts.

The release of the draft genome sequence of P. ramorum strain Pr102, enabled the construction of an oligonucleotide microarray of the entire genome of Pr102. The array contains 344,680 features (oligos) that represent the transcriptome of Pr102. P. ramorum RNA was extracted from mycelium and sporangia and used to compare gene expression across tissue types and in the presence of the host (Rhododendron sp.). The purpose of the experiment was to identify genes whose expression was responsive to tissue types and upon exposure to the host plant for further study. Gene expression studies were...

Quantifying the growth rates of plant pathogens in the laboratory can be useful for predicting rates of disease spread and impact in nature. The purpose of this study was to examine phenotypic variation among isolates of Phytophthora ramorum collected from a foliar host plant species, Umbellularia californica (California bay laurel), naturally-occurring in localities in three regions (southwest, east, northwest) in a 275 km2 study area in Sonoma County. These regions differ topographically, in history of infection by P. ramorum, and in microclimate and plant community composition.We...