ISHS Acta Horticulturae 44: IX International Symposium on Fruit Tree Virus Diseases
PREFACE |
| Authors: | A.F. Posnette, Dr. H.C. Pereira |
| Abstract:
The meeting of which this is the record was the ninth symposium on virus diseases of fruit trees to be held under the title "European" and the first to be regarded as fully international. The organising committee accepted the invitation of the International Society for Horticultural Science to become one of the working parties set up by its Plant Protection Commission. Started in 1954 by a small group of plant pathologists interested in the few virus diseases of deciduous fruit trees then known to occur in Europe, the subsequent meetings became progressively wider in scope and increasingly concerned with viruses perse and virus diseases of fruit trees in all countries. Recently the scope has widened further to include diseases caused by my coplasmas and similar organisms. The 1973 Symposium was truly international: participants came from 23 countries and ideas were exchanged freely inside and outside the formal sessions. I trust that the future of these symposia is assured under the aegis of the International Society for Horticultural Science.
They have proved invaluable during the past 20 years in providing a forum for those concerned with research and development in a rapidly expanding field.
Consequently the catalyst of friendly discussion has been effective in promoting progress towards both an understanding of the viruses and means of controlling the diseases they cause. It is indeed an honour to be asked to open your Ninth Symposium, but your Chairman knows well enough that I am no virologist: my only claim in this field is that, after some years at East Malling I at least know of the great importance of your studies, both for the advancement of biological science and for the progress of the tree fruit industry. Firstly I must congratulate you as a science group on the continuity and purpose of your long series of meetings. Nine Symposia in twenty years, without dwindling away and without loss of identity by excessive growth, is indeed an achievement of good management; I realise that this has demanded a strict limitation of your subject by the exclusion of many tempting and relevant extensions such as citrus fruit trees and vines. This effective concentration is possible because you are still at the most exciting stage where there are major discoveries to be made - new viruses and the vectors of important plant diseases still to be found. This is the stage when a small conference is most valuable to active research workers. Your numbers are approaching one hundred, but in these days of massed meetings we can count any conference which fits into three busses as small. You are assembled in a country in which the laws and trade customs favour the viruses rather than the plant health services. Britain admits an astonishingly free flow of plant material through our seaports and airports. My personal experience with plant quarantine problems has been in tropical countries where very much more thorough precautions are taken. In the orchard industry in Britain this flow of material is more by tradition than by necessity - we could very well grow our rootstocks and avoid the recurrent danger of importing "Sharka" and other virus diseases. Inspection we do have, but with virus diseases certification is necessary at the origin. But first we must demonstrate that we are capable of maintaining the supply of virus-free rootstocks and scion material with which to effect orchard replacement on a national scale in Britain. Intensive research work on fruit-tree viruses has already made progress, as I hope that you will see on your tours this week, to the stage that the replacement of our major orchard crops of apples, pears, plums and cherries with improved varieties, free of known viruses, is now in progress; on a commercial scale it has just begun. You will see this week some aspects of the EMLA Scheme, named from the initials of the Research Stations cooperating in this national programme. The propagation of a wide range of rootstocks and scions for issue, in substantial quantities to the nursery-men of the Nuclear Stock Association for tree fruits, now includes all varieties of commercial importance. As virologists you will realise that we are putting science into practice well before the researches are completed. So little is known of the ecology of these viruses that we shall be undertaking a major study of the health of the new stocks, after they have been distributed for five years. The special plantations of indicator varieties are already growing. The rapid growth of the ornamental horticultural industry in Britain has, however, greatly complicated the ecological pattern of alternate hosts and has increased the problems of isolation of clean stocks. I hope that these clean stock will only be a first stage of the practical application of your findings in virology of fruit trees. The search for varieties tolerant of viruses or even resistant to them seems to be worth pursuing. I am even optimist enough to hope that one day we may be using viruses deliberately as cultural tools to limit the size of trees and to encourage their precocity. We are already moving far from the natural tree forms in our orchards, which were once designed on the same basis as timber plantations, with space for each tree to develop its true natural shape. We have now moved on to hedgerows on a large scale. I believe that in Britain, where sunlight and labour are our limiting factors, we shall eventually grow our apples in beds of small bushes, only about 1.5 metres high, more like tea plantations than tree orchards. Both East Malling and Long Ashton Research Stations are working towards this model, which is dictated by the physics of light distribution. Long Ashton favour a mechanical solution, by mowing the vertical shoots. East Malling is working for biological forms of control (which may indeed present lesser biological problems), by the use of the newly-issued M25 rootstock and by the use of growth-stopping sprays. It is therefore well worth a search for viruses which both check growth and encourage precocity without damage to the fruit. This is indeed speculating on putting science into practice even before the science has been attained, but I find the horticultural world exciting in its possibilities of combining Research and Development into one overall mental picture. The EMLA Scheme is a good example. On the one hand the discrimination between viruses and mycoplasm takes us to the very frontiers of science, while on the other hand the propagation and issue of some 200,000 virus-free graded rootstocks is an extremely practical operation to be carried out by a research station. We are meeting today at a centre where this tradition of combining science with practice is very strong. Wye College was engaged on such a practical exercise in 1913, when setting up a ten-hectare experimental fruit sub-station at East Malling, which has since grown into Britain's largest horticultural station. Similarly, Long Ashton grew from a very practical laboratory built to improve the making of cider. These practical traditions are being well maintained. It was my boast when Director of East Malling, that one of our distinguished senior scientists, Dr. Beryl Beakbane not only worked at the electron microscope on the structure of chloroplasts, but also demonstrated to growers the pruning of plum-trees. I am personally very much aware of this close combination of theory and practice in the horticultural field, because I have become involved in the major reorganisation of the support of science by public funds, which the British Government has undertaken on the advice of Lord Rothschild. The main aim is to produce a closer integretation of research with development. In the new post of Chief Scientist set up for this purpose I work with a small combined team of scientists and administrators to prepare and present the Ministry"s contributions to a "Triple Alliance" between the Ministry, the Agricultural Research Council and the Department of Agriculture and Fisheries for Scotland, each of which has substantial funds for research and development. Firstly we have to secure a national consensus on the priorities for work to be undertaken with the total of public funds available for "R & D" in agriculture, fisheries and food. This is currently about 35m at today's prices (or, perhaps, yesterday's prices). For this purpose we have set up a national Joint Consultative Organisation in which research, development and advisory workers meet with farmers, food manufacturers and administrators to look at research and development problems as continuous tasks. Secondly our team has to help to concentrate suggestions and opinions from a large Ministry, of some 15,000 people, as to what research the Ministry, as a "Customer" should pay for. Thirdly, in cooperation with our opposite numbers in the Research Council and in Scotland, we have to work out a series of interlocking research commissions to cover a very wide field. In order to make this possible all of the many laboratories, stations and farms of the three authorities are working with the Planning Unit of the Research Council to establish an index of the research and development supported by public funds. This is rather a formidable task, but there has been general recognition that it is in everyone's interest to cooperate and I can report encouraging progress. I well realise that in virology you are dependent on the continuous progress of the basic research on cytology and on the behaviour of nucleic acid. Some fear has been expressed that such work may suffer from the new Government enthusiasm for the application of science. Such fears are unnecessary, firstly because the ARC maintains control of a substantial part of its funds, and will safeguard such work. Secondly, because in the Ministry there is a ready understanding that one has to maintain the roots of science in order to achieve the fruits of application. In the wider context of the EEC there is also a determination to secure a better integration of the Research and Development programmes of the nine member countries. Again the essential first stage is the organisation of exchange of information as to what is in progress at present. In discussions among Agricultural Research Directors of the nine countries we are still at the stage of working out the best methods of carrying out this very complex task. This coordination is in order to make best use of funds for research which are becoming available from the Central Agricultural Policy. There is no intention to restrict scientific discussion to Europe or to reduce our contacts with the world science network. In Britain, however, I am in the happy position of being able to hold up horticultural research as the best example which we have of the close working cooperation of the farmer, the research worker and the adviser. Mr. Chairman, I wish you and your colleagues good success in your Ninth Symposium, and declare it to be duly open. | |
