Treesearch

Phytophthora ramorum and P. kernoviae are recently introduced, invasive pathogens in woodlands in southern Britain. P. kernoviae, previously known as Phytophthora taxon C, is a newly discovered taxon, (Brasier and others 2005), found during surveys for P. ramorum in Cornwall, southwest England in November 2003. Both species are aggressive pathogens on foliage and shoots of understory rhododendron, especially R. ponticum. From this infection base they can spread aerially to attack the inner bark of tree stems, especially European beech (Fagus sylvatica) and some Quercus species, causing...

In November 2000 a new Phytophthora originally found on rhododendron stock in Germany and the Netherlands in 1993 and the new Phytophthora believed to be the cause of sudden oak death in California were shown to be the same organism. This development led to a summary Pest Risk Analysis (PRA) for Europe being prepared by Forest Research (FR), United Kingdom. Subsequently, in 2002, the new fungus was formally named P. ramorum. The fact that P. ramorum was known to be present in Germany and the Netherlands led to surveys for the pathogen in nursery material, initially in the United Kingdom...

In 2000, a previously unidentified Phytophthora isolated from rhododendrons in European nurseries and gardens was determined to be the same species – but a different population and mating type – as the pathogen causing sudden oak death in California. Upon recognizing the threats that P. ramorum posed to both wildlands and the nursery trade, countries around the world created quarantine programs to limit the introduction and spread of the pathogen. There are currently seven countries, plus the European Union, with quarantine regulations regarding P. ramorum. The E.U. quarantine required...

In March 2004, a large wholesale nursery in southern California, which ships to interstate receivers, was found to have P. ramorum infected nursery stock. As a result, several of the southeastern states placed a ban on all nursery stock shipping from California. Federal regulatory agencies were not able to provide background information and current research data to the states in a timely manner. As a consequence, many states instituted specific bans on host and associated host plants (HAP) of P. ramorum or on HAP to the genus level. Complicating this situation, many southeastern states had...

A review of the U. S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) regulatory response to Phytophthora ramorum is presented as it impacts nurseries and the nursery industry. The Agency responded in 2004 with three Federal Orders, each more restrictive than the previous one because the appropriate response called for a more robust program. The most recent response was a result of over two million host plants from infested nurseries being shipped over a one-year period to more than 11,000 locations. Consequently, APHIS is working with stakeholders to...

Legislative action at both the European Union (E.U.) and United Kingdom (U.K.) national level has been taken in response to outbreaks of Phytophthora ramorum and, more recently, Phytophthora kernoviae. Measures are aimed at identifying and preventing the movement of infected nursery stock and the containment and eradication of outbreaks at nurseries or in established plantings such as historic gardens and public parks. In addition, legislation relating to a Phytophthora kernoviae Management Zone has been introduced in the U.K.

Diagnostics used by the U.S. Department of Agriculture (USDA), to determine absence or presence of Phytophthora ramorum in plant samples, are based on a combination of tests and depend on collaboration with external laboratories. The system currently in place attempts to maximize limited resources and at the same time provide the most scientifically defensible, accurate, and rapid diagnostics available. Described here is an overview of the current system, followed by a discussion of future plans.

Phytophthora ramorum was identified as the lethal agent of tanoak (Lithocarpus densiflorus), black oak (Quercus kelloggii) and coast live oak (Quercus agrifolia) in central areas of California. Although the geographic origin remains unknown, its severe impact on tanoaks and Quercus species, its limited geographic range and the existence of a single clonal population in North America are indicative of a recently introduced pathogen. Pathogenic invasions of this magnitude are often recognized as serious threats to the maintenance of biodiversity affecting both structure and function of...

The current sudden oak death (SOD) epidemics in Europe and western North America triggered a search of North American oak forests for other Phytophthora species, and the results from the western United States have been surprising. Phytophthora ramorum has been the main quarry, and as an aerial pathogen, it is a surprise in itself. It isn’t alone, however.

Most Phythophthora species secrete a variety of small, hydrophilic proteins that induce a hypersensitive-like response to varying degrees in host and non-host plant species. Our research focuses on the potential role of these proteins in the biology and susceptibility of host species to sudden oak death (SOD). In this paper we reported on the purification and characterization of several proteins from the culture filtrates of P. ramorum media. Exposure of leaf discs from several host species (Umbellularia californica and Rhododendron spp.) to semi-purified protein fractions resulted in...