Public Meetings in Cornwall

 

Two public meetings were held in Cornwall in November 2004 to discuss the establishment of management zones to contain and eradicate Phytophthors kernoviae. The notes of these meetings are below:

Phytophthora ramorum in Cornwall

Meeting of interested parties at St Austell

9th November 2004

1. A meeting was held at St Austell Brewery on the morning of 9th November to update local organisations and interested parties on progress. Around 30 people attended. Most of those present had been at an earlier meeting on 3rd March, at which this update session was promised.
   
   

2. Martin Ward (Plant Health, Defra) opened the meeting by saying that there were some encouraging signs in the campaign against Phytophthora ramorum, but increasing concern about the new Phytophthora which had only just been discovered in the area at the time of the last meeting.
   

3. Dr Joan Webber (Forest Research) described scientific developments since March in relation to both Phytophthora ramorum and the new Phytophthora, which is expected to be given soon the formal name Phytophthora kernoviae. More information is expected from experimental sites being established in two infected woods.
   

4. Roddie Burgess (Forestry Commission) provided an update on continuing woodland survey activity by the FC, since completion of the major survey in the early months of this year. This continued to yield negative results, suggesting that neither disease is widespread.
   

5. Dr David Slawson (Defra’s Plant Health and Seeds Inspectorate) summarised activity across the country by the PHSI to detect and eradicate outbreaks in co-operation with growers and landowners. He also explained the possible approaches to containing and eradicating the new Phytophthora in the area south of Redruth where there are a number of outbreaks. Derek McCann (PHSI team leader in Cornwall) then explained the structure of the local survey operation.
   

6. One participant asked whether the risk assessment was still valid, given the apparently relatively slow spread of P.ramorum. Joan Webber pointed out that the more lurid headlines were thought up by journalists rather than being an accurate reflection of the risk assessments, which could be seen on the Defra and FC websites. We could not be sure what would happen if the pathogen were allowed to build up. Action was being taken on a precautionary basis, while additional information was accumulated. If we waited until the risk was incontestable it would be too late to take action against it.
   

7. Although the indications of reduced levels of disease in nursery stock were welcome, there were still concerns about the possible masking effect of fungicides. Defra agreed to consider whether to do further tests on residues to see whether this might be significantly affecting our ability to detect disease in plants at the time they are traded.
   

8. Questions were also raised about the possible beneficial use of chemical control methods, including chemicals which enhance the plant’s natural resistance mechanisms. Developments in the US are being followed closely to see whether there is anything we can learn for UK conditions. David Slawson pointed out that no chemical control is 100% effective and that destruction of infected material is normally the only completely effective option. Hard pruning with destruction of all cuttings, leaf litter and plant debris around the plant and fungicide use had been permitted on a trial basis on a few historic plants in gardens of heritage value. These would be monitored closely. In relation to disinfectants, Horticultural Development Council-funded work had shown that three products were effective, but one of them was likely to be withdrawn shortly because its manufacturer would no longer be supporting its registration. No data was available yet on the effectiveness of flaming to disinfect paths etc, but the pathogen was known to be relatively susceptible to high temperatures.
   

9. In response to a question on compensation, Martin Ward explained recent developments announced by Defra and the NFU in relation to the nursery sector. Roddie Burgess explained that further grant aid for removal of rhododendrons in woodland was being considered. The point was made from the body of the meeting that some of the eradication work being required in locations which are hard (and therefore expensive) to operate in. Many local woods are unmanaged either because the owners cannot afford to or because they see no benefit in doing so.
   

10. Cutting back of rhododendrons for commercial foliage production might increase the amount of young regrowth which is particularly susceptible to the disease, but on the other hand it could also contribute to the campaign by making areas of rhododendron easier to inspect. The general point was made that any removal of rhododendron from woodland would reduce the risk of the disease spreading.
    

11. Risks of transmission through muddy footwear worn by visitors leaving infected gardens were discussed. Some areas had been roped off, and priority was being given to removal of infected plants near to pathways. Defra could see advantages in raising the profile of risks of plant disease spread in general, and would like to see the development with the garden tourism sector of a hygiene protocol for visitors.
    

12. In conclusion it was agreed that a further update meeting should be convened, at the latest in a year’s time, or sooner if there were significant developments to report.
    

13. Most of the detailed information presented by Defra and Forestry Commission at this meeting is available from their websites at www.defra.gov.uk/planth/pramorum.htmand www.forestry.gov.uk/pramorum.

Phytophthora kernoviae in the Redruth area:

Meeting of local residents at Carharrack

9th November 2004

1. A meeting was held at Carharrack in the evening of 9th November to explain to local residents the recent finding of a number of outbreaks of a new pathogen, which is likely to be given the formal name Phytophthora kernoviae.
   

2. Dr Joan Webber, of Forest Research, presented scientific information on the pathogen which has some similarities to Phytophthora ramorum, but also significant differences. In particular it seems from what we know to have a smaller host range, to be more aggressive on rhododendrons and also capable of killing beech. It is known only from Great Britain, and the great majority of findings have been in woodland within an area of about six square miles, south of Redruth. Like P ramorum it seemed likely that the main risk was from infected rhododendron foliage. This was responsible for producing most of the spores, whereas the stem cankers on trees, although they might kill the tree, did not appear to sporulate. This had important consequences for the measures proposed.
   

3. Dr David Slawson, of Defra’s Plant Health and Seeds Inspectorate set out some of the options for containing and eradicating the pathogen in a designated "disease management zone". The objective would be to eradicate over an agreed period, and to prevent further spread out of the area while eradication is in progress.
   

4. The boundaries of a possible "disease management zone" had not yet been set, and there were also concerns about the negative connotations of the title, although it was hard to think of an alternative that gave a clear indication of what we were trying to achieve. Two possible maps were presented, with slightly different boundaries.
   

5. Possible containment measures to be taken in the zone included controls on movements of susceptible plants and parts of plants out of the zone; hygiene precautions linked to activities such as hedge trimming which presented a high risk of spread; access restrictions; and maintenance of a disease-free buffer zone around the edge of the area. If the boundaries were carefully drawn, this disease-free buffer zone could generally follow arable fields etc which were already clear of host plants. Prohibition on movement of host plant material need not be absolute. It should, however, be possible to allow movement following official inspection and other measures to check that no infection was present.
   

6. Eradication measures would be taken in consultation with landowners, who would normally, under plant health legislation, be responsible for the costs of destroying affected plants. Precautionary clearing of all Rhododendron ponticum within the zone would be highly desirable. In the case of this campaign, Roddie Burgess (Forestry Commission) explained that grant aid would be available towards the cost of clearing woodland sites.
   

7. Challenged as to whether Defra was over-reacting, Martin Ward (Plant Health, Defra) explained that we were taking precautionary action. If our fears were realised and we had not done all we could to prevent an epidemic taking hold then we would be severely criticised. If we were successful in eradicating it, we might never know what damage had been avoided.
   

8. In the discussion which followed a lot of concern was expressed about possible closure of footpaths. Consultation with parish, district and county councillors would be very important, and diversions should be provided if at all possible. Martin Ward agreed with this, and thought that in many cases there might be other options to footpath closure, such as giving priority to clearing infected plants from close to rights of way before tackling others which posed a lower risk of spread.
   

9. Green waste from gardens would be covered by controls on susceptible plant material. If it was moved to the landfill site within the zone it would be exempt from the controls, but Defra would have to check whether the composting and disposal process there was effective. Temperatures achieved during composting would probably be lethal to the pathogen if they were achieved throughout the whole bulk of the material. We also agreed to check on reports that large quantities of soil had been moved onto a site in the area.
   

10. Pressed as to where the infection might have come from David Slawson said that we had investigated various possibilities but had no clear evidence and could only speculate, which would not be helpful. Within Cornwall the distribution of P kernoviae was rather different from that of P ramorum. The most serious outbreaks of P ramorum were in the St Austell area, which was why the meeting for interested organisations had been held there in March. The potential role of the railway embankments in harbouring and spreading infection was raised. Defra agreed this warranted further investigation.
    

11. Asked how far spores could travel, Joan Webber said that they might be blown up to a kilometre, but stressed that the level of inoculum, and the chance of it causing infection, would fall off rapidly with increasing distance from the source. Most of the 24 infected beech trees in the area had been very close to infected rhododendrons, many of them actually touching, with none more than 50 metres away. Birds or mammals could also, in principal, spread spores. It was noted that many of the host species to both types of Phytophthora liked acid soil, but it was not clear whether there was any significance to this.
    

12. In response to concerns that trees might be cleared as part of the campaign, Defra and Forestry Commissions stressed that there was no intention of removing healthy trees; Rhododendron ponticum in woodlands would be the main target. However infected trees were likely to die, and would need to be removed if they became dangerous. This would remain the responsibility of the landowners.
    

13. Chemical treatments were being investigated and trialled, but no chemical treatments were known to be effective at eradicating the disease and destruction of plants by burning was generally a much more secure option. There was also a risk that fungicides could suppress symptoms without eliminating infection. Infection was not believed to move down into roots, but removal of rhododendron roots, rather than just cutting plants off at ground level, would be beneficial because it would prevent regrowth of susceptible plants within the affected area.
    

14. The County Councillor for St Day stressed that many local businesses and a number of regeneration initiatives might be affected by the planned action against the disease. His estimate that this effort may take 18 months to two years was broadly accepted. There were also expressions of support for action, if this was necessary to protect oak and beech trees in the region. One resident asked that the possibility of a replanting scheme be considered, in case we were not successful and a significant number of trees died. Roddie Burgess explained that the Forestry Commission’s Woodland Grant Scheme would be available, subject to applicants meeting the usual qualifying criteria.
    

15. Defra’s inspectorate would not have the resources to check all gardens in the area, but would be relying on notification by householders of suspect symptoms. Although both Defra and the FC had powers under the Plant Health Act to serve statutory Notices, most of our work was carried out with the full co-operation of landowners, growers and the public. However as a backup we would be seeking additional powers within the next few weeks to give effect to the measures proposed for the disease management zone. These measures would apply without the need to serve Notices individually on everyone within the zone.