1. What measures are in place to ensure Scottish seed potatoes remain free of Dickeya infection?
· A zero tolerance for all Dickeya species has been introduced in the Scottish Seed Potato Classification Scheme (SPCS) from 2010.
o All crops entered for classification are inspected at least twice during the growing season. Samples will be taken from crops showing blackleg symptoms (all crops grown from non-Scottish seed and 10% of those grown from Scottish seed), to identify whether Dickeya is the cause.
o The seed potatoes are also inspected before marketing. This will pick up any rots in the tubers, and those from high-risk stocks will be analysed to identify the cause.
o Crops found to be infected with Dickeya will not be allowed to be used as seed. They will only be allowed to be sold as ware for immediate consumption or processing. Conditions will also be imposed to prevent any contamination of other crops.
· Stringent measures are already in place in Scotland to prevent any contact between ware and seed potatoes, to avoid contamination of seed stocks.
· The zero tolerance in the SPCS also means that it is illegal to plant seed potatoes infected with Dickeya in Scotland.
· All non-Scottish seed potatoes brought into Scotland, for seed or ware production, must be notified to the Scottish Government. They will be tested for Dickeya and other diseases on entry. Any ware crops grown from non-Scottish seed will be included in the annual sample of 10% of ware crops which are also monitored. They will be inspected twice during the growing season and included in the annual surveys of tubers. Watercourses at risk will also be monitored.
· In addition to the zero tolerance in the SPCS, new powers have been introduced to enable inspectors to take action where crops are found to be infected with Dickeya, to prevent spread of the disease. The measures to be taken are described in the attached leaflet.
2. What testing has been carried out for Dickeya infection before 2010?
· The new, highly damaging species now identified as " Dickeya solani" was first identified in 2006, and found in England and Wales in 2007.
· The Scottish Government began testing a sample of tubers from the statutory annual Ring Rot / Brown Rot survey for Dickeya in 2006/07.
· Samples of river water taken for the statutory annual Brown Rot survey were also tested for Dickeya from 2007.
· Non-Scottish seed has been required to be notified to the Scottish Government since October 2008, and all samples taken from notified stocks have been tested for Dickeya.
· Samples from high-risk growing crops showing blackleg symptoms were tested for Dickeya in 2009.
3. How often has Dickeya infection been found in Scotland?
· 3 watercourses have been found infected with Dickeya since 2007, in South-East Scotland, the Central region and the North-East. Local potato growers have been advised not to irrigate from the affected watercourses.
· 3 ware crops grown in 2009 from non-Scottish seed have been found to be infected. 2 were found during growing crop inspections and one identified through the tuber survey. Requirements were put in place to prevent spread.
· 3 stocks of seed potatoes from mainland Europe, submitted to SASA in 2009 for variety testing and national listing, were found to be infected with Dickeya. Actions were taken to prevent any contamination of other stocks, and the findings were used for further research.
· 1 stock of non-Scottish seed, brought into Scotland for planting in 2010, was found to be infected and ordered to be lifted and destroyed.
· Dickeya infection has been found occasionally in foreign ware crops brought into Scotland for processing or packing. The companies involved have been advised on measures to prevent any contamination of other stocks via machinery, waste potato material or waste water. Samples of waste water are taken from these facilities to monitor for Dickeya, but there have been no positive findings to date.
4. What has the Scottish Government done to raise awareness of the threat from Dickeya?
· The Scottish Government has worked closely with potato industry bodies and research institutes to raise awareness of the emerging threat posed by Dickeya, through leaflets, articles and seminars at industry events.
· Awareness leaflets issued in November 2009 and April 2010 to all known potato growers made reference to the finding of Dickeya solani in two Scottish ware crops, grown from non-Scottish seed, in 2009. However, it is not our policy to release details of the locations or companies affected by plant health incidents, except where there is a risk to of the infection spreading, in which case neighbours at risk would be informed individually.
· An industry-wide consultation on proposed new control measures was also conducted in December & January.
5. Why was the result from 2009 tuber testing not notified until June?
· Positive findings of any disease are notified to the grower as they are obtained, as soon as testing for the individual crop or lot is completed.
· EU Directives require tuber samples to be taken from both seed and ware stocks, to be tested for Potato Brown Rot and Potato Ring Rot. Approximately 1200 samples were taken in 2009 for this purpose. Testing for each disease takes at least 2 weeks per sample.
· In recent years, the tuber samples from high-risk stocks have also been tested for Dickeya. 340 tuber samples from 2009 crops were tested for Dickeya.
· Until now, testing for Dickeya has been only for information, and has therefore been carried out after the statutory testing for Brown Rot and Ring Rot has been completed. Prior to 1 April 2010, the Scottish Government had very limited powers to act if Dickeya infection was found.
· In light of the new legislation and increased risk from Dickeya, priorities for tuber testing will be reviewed for the 2010 season.
6. How does Dickeya spread?
· The greatest risk of spread is with infected seed potatoes, which will result in infected daughter tubers.
· The infection can be spread to other stocks by physical contact or contamination of machinery and equipment.
· Dickeya is not spread between fields by aerial dispersal or by aphids, but can be spread if infected plant material is scattered, for example when flailing haulm.
· Current evidence suggests that the bacterium does not survive long-term in soil - it has been found to persist for no more than 6 weeks without potato material present, and up to 4 months with potato debris in the soil. However, it will survive and multiply in groundkeepers growing in the field. It is not yet known whether there are other secondary host plants which might also maintain the infection.
· Dickeya bacteria have been found in watercourses, and further research is being carried out into the risk of infecting potato crops through irrigation.
· Conditions favourable to domestic blackleg (Pectobacterium atrosepticum) will also favour Dickeya solani, eg wet conditions during crop growth (including irrigation) and poor storage management.
7. What action are you taking to increase knowledge of this disease?
· Significant research effort has been directed to understanding Dickeya species, and " D. solani" in particular, since the discovery of the more aggressive strain in 2006.
· Research in the UK has been funded by the Scottish Government, the Potato Council and Fera, and has been carried out by SASA,SCRI,Fera and others.
· These projects are investigating all aspects of the biology and behaviour of the disease, including:
· Genotyping the various species and strains, and developing and refining molecular diagnostic tests;
· Examining potential routes of infection, through for example irrigation, machinery, groundkeepers etc;
· Investigating the host range of the disease, to find whether secondary host plants may be involved in transmission;
· Assessing the potential for survival of the bacterium in soils and in different storage conditions;
· The Scottish Government and the Potato Council have recently announced a new 3-year, £500,000 research project. This will deliver better understanding of the epidemiology of " D. solani", including the susceptibility and tolerance of different potato varieties and recommendations for methods to control the disease in potato production.
· The Scottish Government, through SASA, is part of an international working group on Dickeya and has facilitated meetings with researchers from across Europe and Israel to ensure that knowledge is shared and research undertaken by scientists in this field is complementary.