1. Simon Scott, Clemson University Rationalization of lists of pathogens and diseases for which testing should be completed in order to produce foundation grade material.

2. Simon Scott, Clemson University To attain the goal of material free of targeted plant pathogens, FTNCPN must have tested propagating material that it releases for “all” pathogens of economic importance/significance. The resources of the network are not infinite. Many of the virus and virus-like diseases associated with stone and pome fruits are relics from earlier literature. For example : A single incidence of a graft- transmissible condition was reported but no further research was completed to determine the etiological agent associated with the condition.

3. Simon Scott, Clemson University To provide a focus for testing that should be completed under the FTCPN, Ken Eastwell produced two lists of graft-transmissible agents/conditions associated with stone and pome fruits. These lists contained information on diseases which should be tested for, complexes, synonyms, and diseases that require more study to determine the exact identity of the etiological agent involved.

4. Simon Scott, Clemson University For a valid test a known positive control is required. For many of these diseases no such control exists. The lists were scrutinized and rationalized bearing in mind: ● The positive controls known to be located at Beltsville, Prosser, Saanichton, and Summerland. ● The lists of diseases recognized as being present on the North American Continent RSPM No 35 Guidelines for the movement of Stone and Pome Fruit trees and Grapevines into a NAPPO member Country.

5. Simon Scott, Clemson University This reduced the number of diseases for which there are known positive controls available to 25 for Prunus and 15 for Malus, Pyrus etc. Although reducing the number of diseases for which material needs to be screened, the pruning and sifting of the lists has identified agents\diseases whose identity needs to be resolved. Perhaps NCPN could fund projects to resolve some of these dilemmas before they are either included in or discarded from any list completely.

6. Simon Scott, Clemson University It might be expected that reliable testing backed by a positive control could be completed for these agents/diseases (25 and 16) as NCPN moves to establish foundation grade material. The development of appropriate microarrays may facilitate this. There are other diseases of potential economic importance which might be included in testing once the etiological agent has been established. However, many of these need extensive research [Comparable with the effort that Ken has put into identifying the agent(s) associated with apple green crinkle] and would have to be added to any list later.

7. Simon Scott, Clemson University With accelerating technological developments “deep sequencing “ is available to identify virus and virus-like agents in diseases of unknown etiology. However, the presence of a potential agent then has to be supported by research to determine its role in the biology of the disease. An effort comparable to that invested in determining the agents associated with apple green crinkle is needed. The NCPN grapevine group has a nicely defined set of agents with which to work. FTNCPN is a long way from achieving a corresponding set.

8. Simon Scott, Clemson University Acknowledgements: Supplying lists of known positive controls. Ken Eastwell and Bill Howell, Prosser, WA Ken Eastwell, PARC, Summerland, BC Carol Masters, CFIA Saanichton, BC Ray Mock, USDA, ARS, NGRL-PDRU, Beltsville, MD Helping with Rationalization and Reconciliation of the lists. Members of WERA-020: Virus and Virus-Like Diseases of Fruit Trees, Small Fruits, and Grapevines