Treesearch

Annual national surveys for Phytophthora ramorum have been conducted in Canada since 2002. Over 37,361 samples were taken in 2006, which focused on 251 wholesale and retail nurseries across Canada that were either growers or importers of host plants. In 2006, the national survey detected P. ramorum at one wholesale and four retail nurseries in the province of British Columbia. To-date in Canada, there has only been regulatory incidents of P. ramorum at nursery businesses, restricted to areas of the Lower Mainland, Vancouver Island and Sunshine Coast of British Columbia. Trade in nursery...

The Sudden Oak Death Third Science Symposium provided a forum for current research on sudden oak death, caused by the exotic, quarantine pathogen, Phytophthora ramorum. One hundred and seventeen submissions describing papers and posters on the following sudden oak death/ P. ramorum topics are included: biology, genetics, nursery, and wildland management, monitoring, ecology, and diagnostics.

The following industry recommended best management practices (BMPs), designed for growers and/or interstate shippers of host and associated host plants of Phytophthora ramorum, consists of biosecurity guidelines created by and for nursery growers in order to reduce the risks associated with P. ramorum. The control of P. ramorum is based on the insertion of multiple hurdles to prevent the introduction of the pathogen into nursery operations.

Camellias and rhododendrons are important nursery and landscape plants and are known to be highly susceptible hosts of the quarantined plant pathogen, Phytophthora ramorum Werres, de Cock & Man In?t Veld. Nursery inspection can not always occur during optimal conditions for the disease and its detection. The goals of this research were to (1) characterize and document seasonal development of symptoms, including, lesion growth rates and host leaf abscission, (2) evaluate the USDA-APHIS approved laboratory detection methods during four seasons, and (3) access the seasonal potential for...

Sudden oak death (SOD) has had devastating effects on several oak species in many California coastal forests. Phytophthora ramorum has been identified as the primary causal agent of sudden oak death. While the pathogen may be capable of killing mature trees, it is likely that in nature opportunistic organisms play significant roles in the decline and death of infected trees. For example, we have found elevated landing rates of bark and ambrosia beetles (Coleoptera: Scolytidae) on mechanically inoculated coast live oaks (Quercus agrifolia) in California. The tunneling activity of these...

Biological control products were tested in vitro with six isolates of Phytophthora ramorum. These isolates were geographically diverse and were selected based on their pathogenicity to detached Rhododendron leaves. In addition to five commercially available biocontrol products, nine species of Trichoderma were tested. The in vitro tests included dual culture methods and detached Rhododendron leaf assays. Best results were obtained with the actinomycete Streptomyces lydicus (Actinovate®) in both culture and detached leaf tests. There were differences among P. ramorum isolates in their...

The number and retail value of plants destroyed in Washington state nurseries due to Phytophthora ramorum quarantine efforts was estimated using Emergency Action Notification forms (EANs) issued by the United States Department of Agriculture Animal and Plant Health Inspection Service between 2004 and 2005. Data collected from EANs indicate that during this period 17,266 containerized nursery plants were destroyed at 32 nurseries, worth an estimated $423,043. The mean loss per nursery was estimated at $11,188 in 2004, $11,798 in 2005, and at $13,220 per nursery over the two-year period.

A collection of 67 isolates of Phytophthora ramorum from the United States (U.S.), European Union (EU), and Canada was screened using differences in phenotypic traits (pathogenicity, growth rate at several temperatures, and sensitivity/resistance to metalaxyl, dimethomorph, and streptomycin) and for presence of cytoplasmic elements (dsRNA and plasmids). Results of these tests showed a high level of variation among P. ramorum,/i> isolates. Isolates which differed by +/- two standard deviations from the mean are being examined for presence of dsRNA viruses and DNA plasmids. Plasmids were...

Its virulence and ability to spread rapidly throughout the world by various means establishes Phytophthora as one of the most important groups of plant pathogens. Discoveries of interspecific hybridization among Phytophthora species in nature, which could yield novel pathogens, further underscore the threat posed by members of this genus. The ability to accurately and rapidly identify the causal agent of a disease is crucial for developing effective regulatory and disease management strategies, and facilitates the monitoring of changes in pathogen communities as they respond to agricultural...

Coast redwood (Sequoia sempervirens) is a host for Phytophthora ramorum but it is not clear if the pathogen represents a significant disease risk to this tree species. In an on-going field experiment, we are examining the process of infection and the development of symptoms on coast edwood seedlings in naturally infested sites in southern Humboldt County, California. In November 2006, healthy, potted redwood seedlings were placed mid tanoak and bay trees naturally infected with P. ramorum. Symptoms and disease incidence are being observed periodically, and every two months, a subset of...