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Phytophthora pseudosyringae on bilberry (Vaccinium myrtillus) in the South
Pennine Moors SAC: Summary of surveying activities carried out by
the Moors for the Future Partnership 2011-2013.
2013
Prepared by
Moors for the Future Partnership
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Moors for the Future Partnership The Moorland Centre, Edale, Hope Valley, Derbyshire, S33 7ZA, UK T: 01629 816 579 E: [email protected] W: www.moorsforthefuture.org.uk
Suggested citation: Crouch, T. & Walker, J. (2013). Phytophthora pseudosyringae on bilberry (Vaccinium myrtillus) in the South Pennine Moors SAC: Summary of surveying activities carried out by the Moors for the Future Partnership in 2011-2013. Moors for the Future Partnership, Edale.
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Table of Contents
1. Introduction ........................................................................................................................ 5
2. The Roaches Estate ............................................................................................................. 7
2.1 Justification ................................................................................................................. 8
2.2 Methods ...................................................................................................................... 9
2.3 Biosecurity ................................................................................................................. 11
2.4 Results 2011 .............................................................................................................. 12
2.5 Results 2012 .............................................................................................................. 18
3. Heather brash donor sites ................................................................................................ 20
3.1 Background ................................................................................................................ 20
3.2 Justification ............................................................................................................... 20
3.3 Methods .................................................................................................................... 20
3.4 Results 2011 .............................................................................................................. 21
3.5 Results 2012/2013..................................................................................................... 23
4. Discussion ......................................................................................................................... 25
5. Useful Information............................................................................................................ 26
6. References ........................................................................................................................ 27
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List of Figures Figure 2.1: Location of the Roaches Estate (blue boundary) within the Peak District National Park (red boundary). .................................................................................................................. 7 Figure 2.2: Phytophthora pseudosyringae on bilberry at Nickers Pit, Roaches Estate (MFF, 2011). ......................................................................................................................................... 8 Figure 2.3: Black-brown necrotic lesions or banding on stems (Staffordshire County Council (SCC), 2011). ............................................................................................................................... 9 Figure 2.4: Discoloration of the foliage – this may range from foxy red to a washed out appearance (SCC, 2011). .......................................................................................................... 10 Figure 2.5: Clumps of diseased plants next to apparently healthy plants (SCC, 2011). .......... 10 Figure 2.6: The Roaches Estate survey area – an overview 2011. ........................................... 13 Figure 2.7: The Roaches Estate (north) Phytophthora survey and FERA lab results. .............. 14 Figure 2.8: Nickers Pit (located within compartment 8) Phytophthora survey. ...................... 15 Figure 2.9: Compartment 10 Phytophthora survey. ................................................................ 16 Figure 2.10: The Roaches Estate (south) Phytophthora survey and FERA lab results. ............ 17 Figure 2.11: The Roaches Estate survey area – an overview 2012. ......................................... 19 Figure 3.1: Heather brash donor sites surveyed for Phytophthora pseudosyringae during winter 2011. ............................................................................................................................. 22 Figure 3.2: Heather brash donor sites surveyed for Phytophthora pseudosyringae during winter 2012/2013. ................................................................................................................... 24
List of Tables Table 2.1: Summary of LFD tests and lab results for the Roaches Estate 2011. ..................... 12 Table 2.2: Summary of LFD test and lab results for the Roaches Estate 2012. ....................... 18 Table 3.1: Summary of LFD tests and lab results for surveys of brash donor sites carried out during winter 2011. ................................................................................................................. 21 Table 3.2: Summary of LFD tests and lab results for surveys of brash donor sites carried out during winter 2012/2013. ........................................................................................................ 23
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1. Introduction Phytophthora is a genus of fungus-like pathogens that affect a variety of trees, shrubs and other plants. Some species are considered benign; others are pathogenic and can lead to extensive areas of infection and potentially plant death. Several species are notfiable, such as P. ramorum and P. kernoviae. These require containment and eradication measures at outbreak sites (FERA, 2012). P. pseudosyringae was formally described as a new species in 2003 (Jung et al. 2003). In January 2009 the pathogen was recorded on bilberry (Vaccinium myrtillus) in woodland in Staffordshire, and in May 2009 on bilberry in woodland in Cornwall. Initially, it was thought that these were the first records of P. pseudosyringae in the UK (Sansford, 2009). However, it is now known that the first records in the UK date back to 2004 (or possibly 1938, but misidentified as P. syringae) (Sansford, 2012). P. pseudosyringae has now been recorded in Cornwall, Staffordshire, south Wales and Scotland, although the full distribution is not well defined (Sansford, 2011). In addition to the UK, the pathogen has also been recorded in France, Germany, Italy, Spain (nursery stock) and North America (Alaska, California, North Carolina and Oregon) (Sansford, 2012). Most records arise from official surveys for P. ramorum and P. kernoviae, carried out by the Food and Environment Research Agency (FERA). However, subsequent surveys for P. pseudosyringae on bilberry have been carried out at Cannock Chase by Staffordshire County Council (SCC) and within the Peak District National Park and the south Pennines by and The Moors for the Future Partnership (MFF). A number of natural hosts have been identified; however, in the UK, records of P. pseudosyringae are limited to six host species. These include beech (Fagus sylvatica), hornbeam (Carpinus betulus), roble beech (Nothofagus obliqua), rauli (Nothofagus procera), Pieris (Pieris floribunda) and bilberry (Sansford, 2012). Symptoms of P. pseudosyringae in beech, hornbeam, rauli and roble beech include stem cankers and root flare lesions; in bilberry include brown to black necrotic stem lesions and top down dieback of plants (similar to those caused by P. kernoviae) (Beales et al., 2009); and in Pieris are unknown (Sansford, 2012). It is likely that P. pseudosyringae entered the UK on host plants and soil from countries where the pathogen is known to occur. Further entry is very likely as it is not listed in the EC Plant Health Directive (Council Directive 2000/29/EC), is not recommended for listing by EPPO, and is not on the EPPO Alert List or the EPPO Action List. This is because P. pseudosyringae is considered established in the UK (Sansford, 2012). P. pseudosyringae does not require a vector for dispersal, although movement by humans and animals may aid distribution. Furthermore, the pathogen has the potential to spread through aerial and soilborne phases, as well as through the waterways (Sansford, 2012). A rapid assessment (RA) was initiated by FERA in response to the first finding of P. pseudosyringae on bilberry. This RA was initially conducted to determine the status of the
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pathogen in the UK, whether or not a full pest risk analysis (PRA) was required, and to determine future action. However, as a result of finding records dating back to at least 2004 the RA concluded that P. pseudosyringae is established in the UK with no prospect of eradication or official control. Therefore, a full PRA was not required and statutory action was not justified (Sansford, 2012). In April 2011 FERA identified P. pseudosyringae on bilberry on the Roaches Estate (Sansford, 2012), in the south-west area of the Peak District National Park (PDNP) (see Fig. 1). Initially, the outbreak was thought to be contained within a landslide site known as Nickers Pit. This site is fenced off to encourage woodland regeneration; therefore practical to treat with herbicide if contained within this site. Prior to treatment, Natural England consent was given to survey specific areas of the Roaches Estate, only along footpaths and deer tracks, in order to reduce the risk of spreading the disease. Furthermore, as movement by humans and animals aids distribution of the disease, it is likely that the disease, if present, would be found along footpaths and tracks. Following identification of P. pseudosyringae in the PDNP, it was felt necessary to survey potential heather brash donor sites (see section 3).This report provides information on surveys for P. pseudosyringae on bilberry carried out by MFF. The report is divided into two sections; the first covering surveys carried out on the Roaches Estate, and the second covering surveys carried out on heather brash donor sites.
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2. The Roaches Estate
The Roaches Estate is located in the south-west corner of the Peak District National Park Figure 2.1.
Figure 2.1: Location of the Roaches Estate (blue boundary) within the Peak District National Park (red boundary).
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2.1 Justification
P. pseudosyringae on bilberry was reported on the Roaches Estate in April 2011 (Sansford, 2012), in a site known as Nickers Pit (see Figure 2.2 and Figure 2.8). Initially, this was thought to be only the second known incidence globally of this disease on bilberry. Following the identification of the disease by FERA, surveys were carried out by MFF. The aim of the survey was to map the extent, limit the spread, and in conjunction with FERA, Natural England (NE), PDNPA and SCC, inform the best methods for control and eradication of the disease.
Figure 2.2: Phytophthora pseudosyringae on bilberry at Nickers Pit, Roaches Estate (MFF, 2011).
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2.2 Methods
The Roaches Estate was divided into numbered compartments (Figure 2.6). Surveys were then carried out along footpaths, deer trails, and along fence lines within these compartments. This approach was chosen in order to limit the spread of the disease (see also section 2.3 biosecurity). A more structured approach was taken at Nickers Pit (location of first P. pseudosyringae report in compartment 8) by dividing the site into 15 x 15 m squares (see Figure 2.8). This size was chosen because this is the area around an infected plant that would be treated with herbicide if control and eradication of the disease is attempted. As soon as Phytophthora symptoms were identified in a square the surveyor stopped searching and moved onto the next square. In all surveys bilberry was inspected for Phytophthora symptoms, e.g., black-brown banding on stems, discoloration of foliage, and clumps of diseased bilberry (Figure 2.3 - Figure 2.5). Where Phytophthora symptoms were suspected a lateral flow field diagnostic (LFD) test was used to determine the presence of the Phytophthora pathogen. A number of positive LFD tests were verified by sending a sample of the infected plant material to FERA to be confirmed by laboratory analysis.
Figure 2.3: Black-brown necrotic lesions or banding on stems (Staffordshire County Council (SCC), 2011).
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Figure 2.4: Discoloration of the foliage – this may range from foxy red to a washed out appearance (SCC, 2011).
Figure 2.5: Clumps of diseased plants next to apparently healthy plants (SCC, 2011).
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2.3 Biosecurity
P. pseudosyringae is not a notifiable disease; however, it can be spread by movement of infected plant material, contaminated soil, water or tools. Surveyors therefore followed strict biosecurity measures. While carrying out surveys waterproof jackets, trousers and boots were worn. To prevent spread/transmission of the pathogen all of these items, including bags, were washed at 60 °C prior to, and following the visit, and sprayed with Propeller ™ disinfectant and left to evaporate. Jackets, trousers, boots and bags were treated with Propeller ™ disinfectant at the start and end of each footpath, deer track, or at regular intervals if following a fence line, and after every positive result. All equipment used to sample plant material was sprayed with Klercide 70/30 disinfectant and left to evaporate. Surveyors disinfected hands with alcohol gel. Before leaving sites all soil and plant debris was removed from boots using a stiff brush and soapy water and then treated with Propeller ™ disinfectant. Waterproof jackets and trousers were bagged and washed at 60 °C before re-use. Compartments in which Phytophthora had not been confirmed were surveyed before surveying areas where Phytophthora had been confirmed.
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2.4 Results 2011
The results presented below are for Phytophthora surveys carried out at the Roaches Estate between 12 July 2011 and 23 August 2011 by MFF, and additional ad-hoc LFD field tests carried out by Bill Brocklehurst (PDNPA Ranger). In total, 107 LFD field tests were carried out on Bilberry showing symptoms of Phytophthora infection. Of these 107 tests, 67 tested negative and 40 positive for Phytophthora. Of the 40 positive LFD tests, 14 samples were sent to the FERA plant clinic for further analysis. Phytophthora pseudosyringae was identified in 8 samples; Phytophthora spp. in 1 sample; and no pathogen was detected in the remaining 5 samples (Error! Reference source not found.). The maps below (Figure 2.6 - Figure 2.10) show the extent of Phytophthora found during the survey. This should not be considered representative of the limits of the Phytophthora outbreak in the area. Table 2.1: Summary of LFD tests and lab results for the Roaches Estate 2011.
Date Compartment
No. of LFD
No. of negative LFD
No. of positive LFD
Lab result
August 2011 1 1 0 1 Phytophthora pseudosyringae
July/August 2011
2 6 4 2 Phytophthora pseudosyringae & P. spp.
July/August 2011
7 7 5 2 No pathogen detected.
July/August 2011
8 61 33 28 Phytophthora pseudosyringae
July 2011 10 26 22 4 Phytophthora pseudosyringae
August 2011 Road between compartment 7 and 8)
4 3 1 No samples sent to lab.
September 2011
Roaches - Rhamshaw
1 0 1 Not sent to lab.
No date Roaches -Bradley Howel
1 0 1 Not sent to lab.
Total 107 67 40
Figure 2.6: The Roaches Estate survey area – an overview 2011.
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Figure 2.7: The Roaches Estate (north) Phytophthora survey and FERA lab results.
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Figure 2.8: Nickers Pit (located within compartment 8) Phytophthora survey.
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Figure 2.9: Compartment 10 Phytophthora survey.
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Figure 2.10: The Roaches Estate (south) Phytophthora survey and FERA lab results.
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2.5 Results 2012
An additional Phytophthora survey was carried out on the Roaches Estate on 23 May 2012 by MFF and Bill Brocklehurst (PDNPA Ranger). This survey briefly revisited compartments 7, 8 and 10, with the aim of identifying potential spread. In total, 5 LFD tests were carried out on bilberry showing symptoms of Phytophthora infection. Of these 5 tests, 2 tested negative and 3 tested positive for Phytophthora (Table 2.2). Of the 3 positive LFD tests, 2 were sent to the FERA plant clinic for further analysis. The other was carried out on bilberry already confirmed by FERA to be positive for P. pseudosyringae. The map below (Figure 2.11) shows the locations of the additional LFD tests. This map should not be considered representative of the limits of the Phytophthora outbreak in the area. Table 2.2: Summary of LFD test and lab results for the Roaches Estate 2012.
Date Compartment No. of LFD
No. of negative LFD
No. of positive LFD
Lab result
May 2012
7 2 0 2 No pathogen detected
May 2012
8 0 0 0 N/A
May 2012
10 3 2 1 No pathogen detected
Total 5 2 3
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Figure 2.11: The Roaches Estate survey area – an overview 2012.
3. Heather brash donor sites
3.1 Background
Heather brash is an important component in the moorland restoration process. Heather is cut from moorlands in the PDNP and South Pennines in winter, to spread over areas of eroding blanket bog. The brash acts as mulch, reducing the effects of erosion; provides a microclimate for seeds to grow; acts as a seed source; and provides fungi that help moorland plants to thrive. It is transported by helicopter and spread by hand by contractors and volunteers (MFF, 2012).
3.2 Justification Following the outbreak of P. pseudosyringae on bilberry on the Roaches Estate, surveys of potential heather brash donor sites were conducted to mitigate the risk of spreading Phytophthora within the PDNP and South Pennines through MFF restoration activities.
3.3 Methods
All potential heather brash donor sites were surveyed for Phytophthora prior to cutting of heather. Surveys were carried out along paths where paths were available and provided a good coverage of the site. Where paths were not available or where paths did not provide a representative coverage of the site, a ‘W’ shaped transect was used to ensure good site coverage. Where available, a Moors for the Future land cover map based on 2005 aerial imagery was used to aid transect location. Paths/transects were walked by an experienced Phytophthora surveyor and bilberry inspected for Phytophthora symptoms, e.g., black-brown lesions on leaves and stems and patches of brown amongst healthy plants. Where Phytophthora symptoms were suspected an LFD test was used to determine the presence of the pathogen. If no symptoms were observed, random LFD tests were carried out on non-symptomatic bilberry. Up to 5 LFD tests were carried out per site. Where little bilberry was present fewer LFD tests were used (e.g. sites 2 and 7). Positive LFD tests were verified by sending a sample of the infected plant material to FERA to be confirmed by laboratory analysis.
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3.4 Results 2011
The results presented below are for Phytophthora surveys carried out on heather brash donor sites between 29 September 2011 and 16 November 2011 by MFF. Although this is not the optimum time of year to survey for Phytophthora on bilberry (bilberry is a deciduous plant), it was felt that it was important to survey as close to heather cutting as possible. Furthermore, the fact that Phytophthora was identified at one site demonstrates that it is possible to identify Phytophthora during this time of year. In total, surveys were carried out at 10 sites. Of these 10 sites, 6 tested negative and 4 tested positive. Positive LFD tests together with samples of plant material were sent to the FERA plant clinic for further analysis. P. pseudosyringae was identified at 1 site and no pathogen was detected at the other sites (Table 3.1). Figure 3.1 shows the location and survey results for the heather brash donor sites. Table 3.1: Summary of LFD tests and lab results for surveys of brash donor sites carried out during winter 2011.
Date Site No. of LFD
No. of negative LFD
No. of positive LFD
Lab result
29/09/2011 05/10/2011
1 9 7 2 No pathogen detected
04/10/2011 2 2 2 0 N/A
24/10/2011 3 4 4 0 N/A
26/10/2011 4 3 3 0 N/A
27/10/2011 5 3 3 0 N/A
02/11/2011 6 4 4 0 N/A
04/11/2011 7 1 1 0 N/A
08/11/2011 8 4 0 4 No pathogen detected
09/11/2011 9 4 1 3 No pathogen detected
16/11/2011 10 3 1 2 Phytophthora pseudosyringae
Total 37 26 11 (NB many of the heather brash donor sites are located on privately owned land; therefore, site numbers instead of names have been used).
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Figure 3.1: Heather brash donor sites surveyed for Phytophthora pseudosyringae during winter 2011.
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3.5 Results 2012/2013
The results presented below are for Phytophthora surveys carried out on heather brash donor sites between 21 September 2012 and 10 January 2013 by MFF. Although this is not the optimum time of year to survey for Phytophthora on bilberry (bilberry is a deciduous plant), it was felt that it was important to survey as close to heather cutting as possible. Furthermore, the fact that Phytophthora was identified at one site in 2011 demonstrates that it is possible to identify Phytophthora during this time of year. In total, surveys were carried out at 14 sites. All 14 sites tested negative. One sample of apparently symptomatic plant material, but which had a negative LFD result, was sent to the FERA plant clinic for further analysis. The result of no pathogen detected confirmed the result of the LFD test (Table 3.2). Figure 3.2 shows the location and survey results for the heather brash donor sites. Table 3.2: Summary of LFD tests and lab results for surveys of brash donor sites carried out during winter 2012/2013.
Date Site No. of LFD
No. of negative LFD
No. of positive LFD
Lab result
21/09/2012 1 2 2 0 N/A
27/09/2012 2 1 1 0 N/A
05/10/2012 3 1 1 0 N/A
09/10/2012 4 2 2 0 N/A
30/10/2012 5 2 2 0 N/A
30/10/2012 6 2 2 0 N/A
01/11/2012 7 1 1 0 N/A
01/11/2012 8 0 0 0 N/A
09/11/2012 9 2 2 0 N/A
22/11/2012 10 3 3 0 No pathogen detected
30/11/2012 11 1 1 0 N/A
21/12/2012 12 1 1 0 N/A
07/01/2013 13 0* 0 0 N/A
10/01/2013 14 1 1 0 N/A
Total 19 19 0 (NB many of the heather brash donor sites are located on privately owned land; therefore, site numbers instead of names have been used). * No bilberry found at this site
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Figure 3.2: Heather brash donor sites surveyed for Phytophthora pseudosyringae during winter 2012/2013.
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4. Discussion
This report summarises the surveys for P. pseudosyringae on bilberry carried out by MFF. The results should not be considered representative of P. pseudosyringae distribution, which is still not well defined (Sansford, 2011). Furthermore, surveys that did not identify Phytophthora should not be taken as proof of absence of the disease. A number of factors make identifying P. pseudosyringae problematic. For example, many of the leaf symptoms are similar to other diseases that affect bilberry. The most reliable symptom appeared to be the necrotic black-brown stem lesions or banding, particularly if it was located at the base of the stem. Furthermore, often very symptomatic bilberry resulted in a negative LFD test, or a positive LFD test resulted in no pathogen being detected during laboratory analysis. On occasions, a number of LFD tests were carried out before a positive LFD result was achieved. The LFD test itself has two windows; one containing the control line and the other the test line. The test line appears following a positive result; however, it is generally lighter in colour than the control line and often not particularly obvious. Lastly, the time of year may also be a factor, for example, according to FERA; disease symptoms for P. ramorum are likely to be easier to spot during the spring and autumn, and especially after rainy periods (FERA, no date). The results of the surveys carried out on the Roaches Estate demonstrate that the disease is not contained within the Nickers Pit site but present across the northern and southern areas of the Estate (but has not been detected in the central region in 2011 or 2012); although surveying and testing was limited in this region. The results of the surveys on potential heather brash donor sites identified one site with P. pseudosyringae within the Forest of Bowland in the South Pennines. At the time of writing data on the national spatial distribution of P. pseudosyringae is not known and therefore the significance of this finding in our understanding of the distribution of the disease is unknown. The testing MFF are carrying out on potential donor sites cannot guarantee that sites are disease free; however, that an infection has been detected on one of the 10 sites tested indicate that a ‘basic’ survey of sites is valuable in reducing the risk of spread of the disease through restoration activities.
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5. Useful Information
Food and Environment Research Agency (FERA) http://www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/phytophthora/ Natural England http://www.naturalengland.org.uk/ourwork/conservation/biodiversity/threats/phytophthora.aspx Staffordshire County Council http://www.staffordshire.gov.uk/environment/eLand/phytophthora/images/imageshome.aspx
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6. References
Beales, P.A., Giltrap, P.M., Webb, K.M. and Ozolina, A. (2009). A further threat to UK heathland bilberry (Vaccinium myrtillus) by Phytophthora pseudosyringae. New Disease Reports, 19, 56. http://www.ndrs.org.uk/article.php?id=019056 (on-line). Accessed 25 April 2012. FERA (No date). Phytophthora ramorum A practical guide for established parks and gardens, amenity landscape and woodland areas (on-line). The Food and Environment Research Agency (FERA), UK. http://www.fera.defra.gov.uk/plants/publications/documents/factsheets/pramparks.pdf. Accessed 11 May 2012. FERA (2012). PRAs for consultation on pest risk management (on-line). The Food and Environment Research Agency (FERA), UK. http://www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/praTableNew.cfm. Accessed 27 April 2012. MFF (2012). Heather Brash (on-line). http://www.moorsforthefuture.org.uk/heather-brash. Moors for the Future Partnership, UK. Accessed 24 April 2012. Sansford, C. (2009). Phytophthora pseudosyringae – first findings on bilberry in the UK. The Food and Environment Research Agency (FERA), UK. http://www.fera.defra.gov.uk/plants/plantHealth/pestsDiseases/documents/phytophthoraPseudosyringae0609.pdf (on-line). Accessed 25 April 2012. Sansford, C. (2011). Rapid assessment of the need for a detailed Pest Risk Analysis for Phytophthora pseudosyringae. The Food and Environment Research Agency (FERA), UK. Sansford, C. (2012). Rapid assessment of the need for a detailed Pest Risk Analysis for Phytophthora pseudosyringae. Version 4. Second revision of the public version of April 18th 2011. The Food and Environment Research Agency (FERA), UK. Shelley-Jones, K. (2011). Briefing Note to Staff 23rd May 2011 New disease causing death of bilberry in National Park. The Peak District National Park Authority (PDNPA), UK.