Abstract
In April 2009, Defra launched a five-year campaign to manage the riks and diseases caused by the quarantine pathogens Phytophthora ramorum and P. kernoviae in woodlands, gardens, heathland and in the hardy ornamental plant trade in England and Wales. Part of this campaign is to conduct a programme of research to support the overall disease management activities. Recent outbreaks (seven in total to date) of P. ramorum and P. kernoviae on Vaccinium myrtillus (bilberry) in heathland and/or woodlands have been of particular concern due to the potential biodiversity importance of this species and importance of the habitats in which it is found. All these outbreaks have been very recent (2008) and potential approaches to disease and risk management for vaccinium, and in heathland generally, have not yet been evaluated; approaches are expected to be quite different to those used on infected rhododendron. The research proposed here will support the following policy objectives, as detailed in the ROAME i.e. by the end of year 3: (a) the comparative risks to heathlands from each pathogen are better understood; (b) management and disease control methods for heathlands are trialled, evaluated and established and (c) the factors driving pathogen spread and disease development are better understood. The 7 known sites will form the basis of urgent and detailed investigations that will support the development of risk management approaches to these two pathogens on vaccinium and the important habitats in which it occurs (heathland and woodland). Investigation into possible management, containment and eradication strategies for P. ramorum and P. kernoviae in heathland will be a key objective of the research. The research will be closely coordinated and linked with the eradication and containment actions done by Defra/Fera on the ground. A range of management options will be examined through discussion with stakeholders, direct experimental research and modelling in order to develop strategies appropriate for these sensitive habitats. Options to be considered will include cutting, burning, digging, herbicide or fungicide application, or a combination of these approaches. Research will also determine the factors driving and influencing epidemics of P. ramorum and P. kernoviae on vacciunium, especially in heathland environments. Current risk assessments indicate that the ongoing threat posed by these two pathogens to vaccinium and heathland in the UK is high. This project will investigate the epidemiology of the pathogens, both in open heathland and for heathland plants forming understorey in woodlands, in order to support disease management decisions and actions on the ground. There have also been two recent outbreaks of a third phytophthora species (P. pseudosyringae) causing disease on heathland in Staffordshire and Cornwall. A limited study will be undertaken to compare the key aspects of the biology and management of all three Phytophthora spp. to further inform the development of disease management approaches for P. ramorum and P. kernoviae on vaccinium. Using the range of infected sites available, experimental work will be conducted to characterise the outbreaks and examine the impacts of biotic and abiotic factors on epidemic development in heathland plants. Each epidemic will be mapped at the start of the project and then regularly monitored to measure disease progress and pathogen spread. Inoculum sources including infected plants, residual inoculum in litter, soil and water courses (if present) will be quantified and inoculum movement in splash and wind-driven rain monitored on a regular basis. Meteorological data will be collected in the infected area to provide data for analysis of the effects of weather on development of the epidemics. The data will be analysed to identify correlations between meteorological factors, inoculum production and dispersal, and plant infection. Analyses will determine whether these criteria vary according to pathogen, host species or other factors. ArcGIS methodologies will be used to visualise and analyse data collected through detailed mapping of the epidemics at local and regional scales. Investigation of the impacts of heathland species life-cycles and growth habits on disease spread will be an important factor in assessing the status of epidemics and their management in heathland. The impact of these biological and management factors will be fully explored through surveys and observation of the selected outbreaks sites, but also through gathering of intelligence from other outbreak sites across the UK as they emerge (extensive surveys are to be undertaken across England, Wales and Scotland in 2009). This monitoring work will link in with research to be carried out under funding from the Scottish Government (RERAD project CR/2008/55)) into the risks posed by P. ramorum and P. kernoviae to similar ecosystems in Scotland. The data will also be used within the Phytophthora Disease Management Programme in England and Wales and to run models developed by Cambridge University/Rothamsted Research/Fera (Defra Project PH0406) to examine the potential impact of control strategies on heathland epidemics in England. In conclusion, the work will determine the best approaches for managing P. ramorum and P. kernoviae on vaccinium, in healthland and in woodlands, based on epidemiological and control studies that underpin risk assessment and risk management. In addition, a review of the impacts of Phytophthora on biodiversity in heathland and woodland habitats will be undertaken. A desk study will evaluate the likely impact of different rates of spread on heathland species susceptible to Phytophthora infection and will assess the knock-on effects on higher trophic groups and on designated sites. The study will also assess the impacts of the disease on ecosystem services. In order to evaluate the potential effects of Phytophthora control treatments on vegetation communities, a field study will be established and baseline assessments will be made before treatments are applied.
United Kingdom