Treesearch

Real-Time PCR technologies offer increasing opportunities to detect and study phytopathogenic fungi. They combine the sensitivity of conventional PCR with the generation of a specific fluorescent signal providing both real-time analysis of the reaction kinetics and quantification of specific DNA targets. Before the development of Real-Time PCR and the opportunity to provide quantitative data, the risk of false-positive PCR results due to detection of dead cells was considered only a minor setback. This, therefore, has led to a renewed interest in the risk of false-positive PCR results. In...

Emergency phytosanitary measures to prevent the introduction into and spread within the European Union (EU) of Phytophthora ramorum Werres, De Cock & Man in 't Veld. have been in place since 2002. Surveillance across the EU, has confirmed the presence of P. ramorum on nurseries and retailers in 15 member states. Phytophthora ramorum has been confirmed on 14 plant genera at nurseries and retailers, with 96 percent findings being made on Rhododendron, Viburnum and Camellia, which are the three genera currently regulated for internal movement within the EU. More detailed analysis of data from...

Big Sur is one of the most ecologically diverse regions in California and well recognized as a biodiversity hotspot for global conservation priority. Currently the region is experiencing substantial environmental change due to the invasion of Phytophthora ramorum, the plant pathogen causing the forest disease known as sudden oak death. First confirmed in 2000, P. ramorum has spread quickly through many canyons in Big Sur killing large numbers of ecologically important oak (Quercus sp.) and tanoak (Lithocarpus densiflorus) trees with little indication of slowing. Despite these impacts...

Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. Infected bay laurel leaves are more likely to abscise than uninfected leaves, resulting in an accumulation of inoculum at the forest floor. The pathogen survives the dry summers in a proportion of attached bay leaves, but the histology of colonization during the survival phase and the propagules responsible for survival are unknown. This study focuses on summer pathogen survival associated with bay laurel in...

To date (February 2007) there have been 160 outbreaks of Phytophthora ramorum in gardens or woodlands in the U.K. Current EU policy requires that appropriate measures be taken to contain P. ramorum in such situations. In the U.K., the measures have either been aimed at eradication, through destruction of infected plants, or at containment to minimise the risk of P. ramorum being spread from the site to other areas. Of the 160 natural outbreaks recorded, 123 are ongoing, whilst the remainder are considered to have been eradicated as no further plant infections have been recorded, although...

Bay laurel (Umbellularia californica (Hook. & Arn.) Nutt.) is the primary reservoir host of Phytophthora ramorum Werres, De Cock & Man n?t Veld in coastal California woodlands. Non-lethal foliar lesions on bay laurel trees support the majority of pathogen sporulation during the winter et season and appear to provide the primary means of surviving through California?s arid Mediterranean summers. Previous experiments have shown that the proportion of symptomatic bay leaves from which P. ramorum can be successfully isolated decreases during the summer. In addition, isolation of P. ramorum...

The history of the regulation of action against Phytophthora ramorum and P. kernoviae in the EU and U.K. is briefly summarised. For the former there are EU controls on the import of host plants, and the internal regime of plant passporting has been extended to cover Rhododendron, Viburnum and Camellia. There are also requirements relating to containment and eradication at infected nurseries. For P. kernoviae the U.K. has taken action through national legislation which includes the introduction of a management zone in the most heavily infected area of Cornwall. Some pilot work on the...

Nurseries in the southeastern United States that received ornamental plants in 2004 colonized by Phytophthora ramorum and the surrounding urban areas are being monitored to determine if this pathogen has escaped and become established. At the same time, the prevalence and diversity of other species of Phytophthora are being investigated. Water and field soil were collected from six retail nurseries in Florida in February and March 2006 and from three retail nurseries in South Carolina in both spring and fall 2006. Water samples (1 to 2 liter) were collected from streams, retention basins,...

Infection of compatible plants by Phytophthora spp. often leads to a decline in stomatal conductance and photosynthesis, although the mechanistic basis for such declines is not completely understood. In many cases, declines in leaf gas exchange rates have been linked to losses in water supply capacity associated with root and/or xylem. However, the reductions in gas exchange may not be proportional to changes in hydraulic capacity, and may be observed in non-invaded regions, suggesting the presence of a toxin, or host-derived signal, that is responsible for some of the physiological...

Access to timely and accurate sudden oak death (SOD) location data is critical for SOD monitoring, management and research. Several websites (hereafter called the OakMapper sites) associated with sudden oak death monitoring efforts have been maintained with up-todate SOD location information for over five years, providing information and maps of the most current spatial and attribute data on Phytophthora ramorum distribution in California to the public, the California oak mortality task force, and researchers. In addition to the spatial locations of P. ramorum, the OakMapper websites...