PREFACE

Dr. Michael Hollings (UK) and Dr. Roger Lawson (USA) retired as chairman and secretary, respectively, of the ISHS working group Virus Diseases of Ornamental Plants. The participants of the symposium are expressing their deep gratitude to these two men for their engagement. Dr. Roger Lawson was elected new chairman of the working group, Dr. Alan Brunt (UK) and Dr. Renate Koenig (Federal Republic of Germany) will serve as secretary and vice-chairman, respectively. The VIth International Symposium on Virus Diseases of Ornamental Plants will hopefully be held in 1984 at Cornell University, Ithaca, N.Y., USA.

R. Koenig

OPENING ADDRESS

ladies and Gentlemen,

It is a great honour for me to open the 5^th International Symposium on Virus Diseases of Ornamental Plants here at Bad Harzburg, and it is a very pleasure for me to welcome you on behalf of myself and of my colleagues of the Institut für Viruskrankheiten der Pflanzen at Braunschweig. Moreover, I am glad to offer to all of you the salutations of the German Phytomedical Society. Prof. Heitefuß, the president of this society regrets very much to be prevented from coming and he asked me to welcome you in his place. Last but not least, the president of our institution, the Biologische Bundesanstalt für Land- und Forstwirtschaft, feels happy to have you as well known specialists of an important phytopathological branch as visitors in Germany; he will welcome you at Braunschweig tomorrow.

The symposia of the ornamental plant virus group are well known since years, indeed this one is number 5 already. You are members of a well established familiy of research workers and it is superfluous to emphasize the importance of your work and of this meeting once more. You know each other, and there exist many collaborations; perhaps I am the most stranger amongst you here. In fact, I am not an ornamental plant virologist, I am not even tightly bound to any group of cultivated plants, but I work with plant viruses of any origin without preference for certain host plants being interested mainly in particle characteristics. So I am not a well-suited counterpart for discussions on symptoms or on resistances nor a connoisseur of any particular plant you are concerned with. I have to apologize for all my ignorance in your field and I can only hope, you may not be shocked too much in having such an opening speaker and chairman.

Ornamental plants belong to a wast number of plant families and a large number of virus diseases is already known. This number does increase each year, not only because you look closer at the established ornamental plants with the time going on, but likewise because more and more plants get discovered to be useful as ornamentals.

The appreciation of a natural environment within the artificial space in which millions of people of the highly industrialized countries have to live in, has created a great demand for ornamental plants and, perhaps, some luxury in using them. This has, in turn, stimulated breeding, culture and trade of these plants and has given to some poorer nations having appropriate climatic conditions possibilities to extend their export, to increase the number of working places and to ameliorate their balance of trade. By this means ornamental plants have become a commercially important matter. This expansive use of ornamentals offers to the virologists a wide field for studies and, perhaps, an ornamental plant virologist has an unique possibility to find new and possibly exotic forms of plant viruses or viroids. To extend our knowledge of all these viruses, all the techniques of the present-day virology have to be used. This necessicates collaborations world-wide and gives employment also to the poor people of virus particle researchers as e.g. myself.

The world-wide trade, the exchange of ornamental plants has its inherent danger: the possibility of spreading viruses. It is certainly not accidental that on the programme of this symposium a complete session is devoted to the questions that arise by this trade, that is the quarantine regulations and related subjects. I believe, not only the survey of the legal importations of eventually virus containing ornamental plants raises many difficulties, but likewise the private, small-scale importations by tourists, that, of course, have by no means bad intentions when bringing home nice or exotic plants for their gardens. In this way viruses may enter new areas and become important in a crop that does not exist in the original area. May be that the danger of importations is much less than supposed by a nervous contemporary, and may be, on the other hand, that invasion by a virus of a smaller area-like Europe- is inevitable, provided the environmental conditions and the presence of vectors and hosts are given, it is wise and necessary in any case to think over possibilities to prevent virus spreading as much as possible. I hope that your discussions on benefits and limitations of quarantine regulations may result in a deeper understanding of the recommendations the specialists can offer to administrators.

Well, let me have a look at another point finally: research work is not industrial routine work, but implies, as we all know very well, the performance of many experiments to get insight into new facts, and by no means all of these experiments are successful. And if we try to understand our experimental results or failings by working hypotheses we often learn that our ignorance of the matter we are working with is a very great one. Therefore it seems to me that an important characteristic of a research worker is not to be discouraged or demoralized by irreproducible or strange results nor by learning about the worthlessness of a nicely constructed, heretofore well estimated hypothesis. To overcome those depressions one has to be cheerful. A German proverb says: "Wer schaffen will, muß fröhlich sein"; that means that creative work succeeds predominantly with cheerful persons. So I wish you good and fruitful discussions and forwarding ideas, but likewise fun and enjoyable impressions during this symposium.


WELCOME BY PROFESSOR DR. GERHARD SCHUHMANN

Ladies and Gentlemen,

It is a great pleasure and honour for me on behalf of the Biologische Bundesanstalt and on behalf of the German Phytomedical Society to welcome the participants of the Fifth International Symposium on Virus Diseases of Ornamental plants. Together with my colleagues I am most happy that we may welcome you here in Braunschweig in one of the two centres of the Biologische Bundesanstalt.

We are glad, indeed, that you were able to come to us from altogether sixteen countries of all five continents. Many of you had to travel long ways - frequently on their own expense - to attend this symposium. I am, therefore, hoping - and this is my sincere wish to you - that your stay in Germany will satisfy your expectations and that you will return with the feeling that it was worthwhile to come.

In the Federal Republic of Germany research on diseases of ornamentals has, unfortunately, not yet received that amount of attention that it would deserve according to the economic importance of ornamentals. The production value of ornamentals in the Federal Republic of Germany has reached almost that of wheat. The memory of human starvation in two world-wars is probably a major reason for this negligence and the still dominating role of phytopathological research into the main food crops.

As you all know, the multitude of plant species used as ornamentals, the large number of different varieties and the rapid change in species which are in vogue impedes a thorough study of the many individual diseases of ornamentals. The worldwide trade and the cultivation of cutting material in other countries with more favourable climatic conditions are greatly increasing the phytopathological problems. The question of quarantine which you are discussing today are gaining special importance. Also, virology is a rather young branch of phytopathological research which later than mycology or entomology has found the attention which it deserves. All this are good reasons to foster the international cooperation and the exchange of experience among scientists. The Biologische Bundesanstalt is hoping to take its share in this task with its Plant Virus Institute.

A brief introduction of the most important German institutions that deal with phytopathology especially with virus diseases of plants might be useful for the cooperation.

As to the figures, the largest research organization in the whole field of plant pathology and plant protection is the Biologische Bundesanstalt für Land- und Forstwirtschaft (Federal Biological Research Centre for Agriculture and Forestry) which is subordinated to the Bundesminister für Ernährung, Landwirtschaft und Forsten (Federal Minister for Food, Agriculture and Forestry). Its centres are in Braunschweig and in Berlin-Dahlem. Eight external institutes in different parts of the country belong to the Bundesanstalt. These institutes like for instance the Institute for Diseases of Vegetables and the Institute for Diseases of Grapevine deal predominantly with harmful organisms of certain groups of cultivated plants among them viruses and mycoplasma-like organisms. The Institute for Nematology works on viruses of beets and the significance of nematodes as vectors of virus diseases.

Here in Braunschweig the former two central institutes for virus research were combined to one Institute for Virus Diseases of Plants. Nine scientists are working here especially on methods to diagnose viruses, e. g. by means of electron microscopy and serological methods. By meristem culture it was possible to obtain virus-free plants from important infested cultivars. In addition epidemiological problems and those of the investigation on the biology of the virus vectors are dealt with. Another field is the examination of the virus-resistance of cultivars.

In Berlin at the Institute for Bacteriology etiologically unclear mycoplasma diseases are investigated.

As you will find in your symposium folders further information, I do not intent to go into the details of the tasks of the Biologische Bundesanstalt, among which in general are investigations on diseases of plants as well as the testing, admission and official registration of pesticides.

At the universities phytopathological research is mainly done within the faculties of agriculture, forestry and horticulture. There are institutes of phytopathology at the universities of Bonn, München-Weihenstephan, Giessen, Göttingen, Hannover, Stuttgart-Hohenheim and Kiel. Partly they have established their own departments for virus research.

In addition to that, phytopathological research is realized in a few other university institutes but it would lead me to far away from my subject to quote them all.

In the Federal Republic we also have some regional agriculture and horticultural research centres under the authorities of the different Bundesländer (states). These centres, e. g. in München, Stuttgart, Neustadt a. d. Weinstrasse, Freiburg and Würzburg also work on plant virus diseases. Among the tasks of the official Plant Protection Service under the authorities of the Bundesländer are:

1. Supervision of crops and stocks of plants with regard to the occurrence of harmful organisms and diseases. That means for example the examination of nurseries for sharka infection.
2. Supervision of the dispatch of plants and plant products as well as the issue of phytosanitary certificates.
3. Providing for advisory, instructive and monitoring services.
4. Reporting on the occurrence and spread of harmful organisms and diseases.
5. Participation in the testing of pesticides and plant protection equipment as well as other official tasks.

The organization of the Plant Protection differs from one Bundesland to the other as plant protection is not only basing on federal law but also on state law. In spite of this there has existed for decades a close cooperation between the Biologische Bundesanstalt, the Plant Protection Service of the Bundesländer and the university institutes which altogether discuss their problems on one or two annual meeting. An essential link is also the German Phytomedical Society which among many other working groups has also established one for virology.

The next step to further extension of the exchange of experience leads us to international contacts and we shall continue to reinforce, whereever possible, the existing ties. This symposium offers in that sense, especially because of the limited number of participants, a great opportunity.

I further wish you a successful course of the session and a pleasant stay in Germany.