OPENING ADDRESS

I have the particular pleasure and honor to open the Xth International Symposium on Fruit Tree Virus Diseases and to be the first to welcome you.

Dear colleagues, the 100 participants come from 19 European and 5 overseas countries, which certainly justifies the new name of "International Symposium", dating back to a foundation by 21 virologists in 1954.

Together with my colleagues I am most happy about the fact that we may welcome you to the Xth meeting here in the Federal Republic of Germany. I would like to welcome all of you most cordially, especially in the name of the organizers who provided for the most important preparations to carry through this meeting.

Our very special welcome is directed to the Chairman of the Committee of these symposia, Dr. Posnette, director of the East Malling Research Station. Dear Dr. Posnette, the name East Malling has here in our ears an awe-inspiring sound and we estimate your great scientific capacity on the field of fruit cultur.

Ladies and gentlemen, in this venerable circle of recognized scientists I do not dare to quote any other names and I ask you kindly to agree with me.

Let me merely give my sincere thanks to Ministerialrat Dr. Priew who as the representative of the Ministry for Food and Agriculture will subsequently speak to us. The Federal Minister for Food and Agriculture provided for sufficient resources to realize this Symposium and thus expressed his affection towards science. We ask you, Dr. Priew, kindly to pass our thanks on to him.

We appreciate particularly the support which the Plant Protection Service and the Institut für Obstkrankheiten (Institute for Diseases of Fruit Plants) der Biologischen Bundesanstalt (Federal Biological Research Centre) receives from the Minister für Ernährung, Landwirtschaft und Umwelt (Minister for Agriculture) of the Bundesland Baden-Württemberg, who is today represented by Ministerialdirigent Dr. Flad, whom we also welcome gratefully.

Finally we have to thank the University of Heidelberg for leaving this meeting-room at our disposal.

Dear auditors, a number of specific papers is waiting for you and I, as the head of a research center with manifold tasks, cannot make my own contribution to that. I only remember from the period of my first scientific

steps that I took under the shelter of Dr. Thiem who then led the Institut für 0bstkrankheiten of the Biologische Bundesanstalt here in Heidelberg that in Germany as well as in other European countries latent virus infestations at stone and pome fruits are wide-spread. Because of using vegetatively propagated rootstocks the different varieties, especially of apple, are heavily attacked by viruses. It is the merit of scientific research that it was possible during the recent years to illuminate the economic consequences of these virus diseases and to find a way to eliminate them by the application of thermotherapy. We are also concerned about apple proliferation which has appeared in southern regions of Germany and which in the last two or three years has spread increasingly in apple plantations. You will have the opportunity to study it thoroughly during this symposium when it will demonstrated to you at visits of commercial plantations and on the experimental field of the Institut für Obstkrankheiten. Another disease to mention is pear decline which for a short period of time has been found in the plantations. The sharka disease of stone fruits which presumably was imported during the world war II from southern Europe represents - as it is transmitted by aphids - a serious threat to plum cultivations existing particularly in the south.

In appreciation of all knowledge a lot of problems in the field of fruit tree virus research still remain to be solved; problems which can only be tackled on the basis of international cooperation in which the Federal Republic must have a special interest.

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. 7 external institutes in different parts of the country belong to the Bundesanstalt. These institutes like for instance the Institut für Obstkrankheiten (Institute for Diseases of Fruit Plants) in Dossenheim that is scheduled for visit tomorrow deal predominantly with harmful organisms of certain groups of cultivated plants. In Dossenheim for years the stress has been lying on the research of viruses and mycoplasma-like organisms. Among the tasks of the Institut für Gemüsekrankheiten (Institute for Diseases of Vegetables) Hürth-Fischenich you will find the investigation on vegetable viruses. Methods for the identification of viruses in grapevine and for the production of "virus-free" plants are being developed in the Institut für Rebenkrankheiten (Institute for Diseases of Grapevine) in Bernkastel. The Institut für Hackfruchtkrankheiten und Nematodenforschung (Institute for Diseases of Root-Crops and Nematology) in MUnster works on viruses of beets and the significance of nematodes as vectors of virus diseases.

In Braunschweig the former two central institutes for virus research were combined to one Institute for Virus Diseases of Plants. 11 scientists are working there specially 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 Institut für Bakteriologie (Institute of Bacteriology) aetiologically unclear mycoplasma diseases and diseases suspected to be caused by a virus are investigated.

As you will find in your symposium folder 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, Gie*en, 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. To satisfy your specific interests we have planned to visit during this symposium the Institut für 0bstbau (Institute of Pomology) of the University of Bonn. In the Federal Republic we also have some regional agricultural and horticultural research centres under the authorities of the different Bundesländer. 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 occurence 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 occurence 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 Service 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 without any doubt to international contacts and we shall continue to reinforce, whereever possible, the existing ties. The symposium beginning today offers in that sense, especially because of the limited number of participants, a great opportunity.

I wish you a successful course of the session and hope that you all, especially our guests from abroad will go back in the conviction that your trip to the Federal Republic of Germany was worth while.

As a non-virologist I shall not be able to take part in the next symposium but I hope to be able to meet most of you again on the Third International Congress of Plant Pathology to be held in 1978 in München.


WELCOME

Ministerialrat Dr. H. Priew

Ladies and Gentlemen,

It is a great honor for me to transmit the very best wishes from the Bundesminister für Ernährung, Landwirtschaft und Forsten der Bundesrepublik Deutschland, Mr. Josef Ertl, and to welcome you in his name. At the same time I would like to pronounce my satisfaction about the fact that the International Committee for Cooperation in Fruit Tree Virus Research has chosen to meet in our country, the Federal Republic of Germany.

Yesterday the scientists investigating on virus diseases of small fruits already gathered for their Ist International Symposium. I would like to welcome them, most of who also participate in this meeting, as well, wishing you all a successful exchange of ideas and close cooperation.

The great importance of the international exchange of experience for research cannot be overestimated. In spite of budgetary difficulties now prevalent in most countries, we should continue to further such cooperation. The exchange of experience does not only contribute to advance and enlarge the personal experience of the scientists gathered here but has also positive effects on the research stations they are working in. Results of the research work done in other countries often show new ways to solve one's own problems and help in using technological and financial means at disposal more effectively.

Not the least objective of this exchange is to solve problems of the agricultural practice more rapidly and thus to help the consumer as well.

Ladies and gentlemen, because of the bad development of the world's food situation the supply of the population with food will continue to be of predominant importance. World wide one of the most essential objectives has to remain the maintenance of a strong agricultural sector which must enjoy an equal position compared to the other sectors of a modern economy. One of the main tasks of this policy is to supply the population with products of high quality at reasonable prices and simultaneously to guarantee those who work in the agricultural sector an income concordant with the general development.

To achieve these objectives we have to elaborate a scientific basis and to enlarge our knowledge, as these represent an important help for the decision-making process in agricultural and alimentary politics. Therefore the research stations subordinated to my ministry are to

focus on the problems below:

1. Maintaining and improving the quality of the products of the agricultural and alimentary sector.
2. Developing non-polluating production and manufacturing processes.
3. Ensuring an appropriate self-supply.

I would like to explain briefly the important of these tasks assigned to the research sector at the example of fruit production in the Federal Republic of Germany.

As you might know, our fruit crop is each year subject to particularly strong fluctuations. One of the main reasons for this is, in addition to weather influences, the high percentage of the so-called "Streuobstbau" (scattered fruit trees on farm land), which only every two or three years produce a full crop. For example in 1974 the apple crop remained 30 % below the average of the years before, while exceeding it in 1975 with 17 %. These strong fluctuations in fruit production can be compensated by imports but the supply of the markets and thus prices as well as the income of the producers fluctuate to a similar undesired extent. To solve this problem, intensive fruit growing represents a possible way to attain regular crops and thus to stabilize prices and imports. Research works on breeding, on cultivation methods and rootstock problems are of special importance.

Intensive fruit growing preconditions that losses caused by diseases and pests are kept on the lowest possible level. This has to be achieved by measures of low polluating effect with the highest possible profitability for the producer. In this context research on fruit tree diseases caused by viruses and mycoplasma-like organisms is very important as these diseases lead to a high and frequently permanent crop loss and a decrease of quality. The losses are the more serious as fruit plantations compared to other agricultural sectors require high investments and maintenance costs. The diseases, however, are mostly detected very late. I think it is not necessary to go on talking about the economic effects of viruses in such a distinguished circle of scientists. How important my ministry considers these diseases to be, may be drawn from the regulations to control fruit tree virus diseases, to be issued as soon as possible. These regulations provide that fruit plants may only be sold when they originate from plants which, in an official examination, have been found to be free of economically important virus diseases. The examination procedures have to correspond to the then latest scientific knowledge.

It is a positive fact that the elimination of viruses can be carried through with methods which, similar to the breeding, do not affect our environment negatively. Without difficulties we can already today supply our nurseries with tested scion wood of all important varieties. Within a short period of time we shall also have enough root-stocks at our disposal. At the end of 1975 there were about 1.5 million apple rootstocks originating from tested mother-plants; that is about 75 % of our need. During this season of sales (1976) young trees which have been brought up under controlled conditions can be sold with a special virus test label.

Ladies and gentlemen, the efforts to establish fruit tree plantations with virus-free young plants and to keep them healthy as long as possible do require permanent close contact with research. On the other hand the desires originating from the practical side, again and again give new impulses to the science. This symposium serves to a world wide exchange of experience in that specific sector of fruit growing. Therefore I want to give my best thanks to Prof. Dr. Schuhmann, president of the Biologische Bundesanstalt, and his staff for organizing this meeting. I hope your meeting will be successful and I wish you personally a nice stay in this old university town and, for the benefit of fruit production all over the world, a lot of new impulses which may inspire you to new research projects.


WELCOME

Ministerialdirigent Dr. M. Flad

Ladies and Gentlemen,

I have the great pleasure to welcome you here in the Bundesland Baden-Württemberg where you are going to hold your Xth International Symposium on Fruit Tree Virus Diseases. I also have the honor to pass on to you the compliments of the Minister für Ernährung, Landwirtschaft und Umwelt (Minister for Food, Agriculture and Environment), Mr. Gerhard Weiser, who was not able to come here today.

Your meeting takes place in Baden-Württemberg, which belongs to the climatically most favored areas in the Federal Republic of Germany. The highest temperatures in the average of a year are measured in the region of the Kaiserstuhl (a mountain near Freiburg). Therefore it is easy to understand that fruit-growing is one of the most important agricultural sectors in our Bundesland. Merely the actual fruit plantations cover an area of more than 25.000 hectare, corresponding to 29 % of the total plantation area in West Germany. The second position is occupied, however in considerable distance, by the Land Niedersachsen with a share of only 19,6 %. During the years after the War 444 cooperative fruit plantations covering an area of altogether 2452 hectare were established in Baden-Württemberg. So they amount to 10 per cent of the total fruit-growing area of Baden-Württemberg. The principal fruit-growing regions are lying in the valley of the Rhein (Rhine) - here in the region of Heidelberg we are right in the centre of such a fruit-growing region - near the Bodensee (Lake of Constance) and in the central part of the valley of the Neckar.

The most important fruit is the apple but other fruits like the plum - I remind you to the well-known early plum region of Bühl - or the cherry are important, too.

Unfortunately the - as to the climate - favorable location also supports the occurence of diseases and harmful organisms. In consequence it is obvious that the Plant Protection Service here has always been obliged to concentrate on fruit-growing. Not without good reasons did the Biologische Bundesanstalt für Land- und Forstwirtschaft (Federal Biological Research Centre for Agriculture and Forestry) transfer its Institut für Obstkrankheiten (Institute for Diseases of Fruit Plants) from Stade to Baden-Württemberg. Of all the measures to control harmful organisms at fruit plants taken by the Plant Protection Service, especially the activities to control the San José-scale reached publicity, when after World War II this insect threatened to destroy the fruit-growing in the region of Heidelberg and Mannheim. By intensive chemical control it was possible to repel the attack within a few years. Later the Landesanstalt für Pflanzenschutz (Plant Protection Centre of the Land) started to control the harmful organism biologically with the Aphelinid Prospaltella perniciosi. The San José-scale was repelled that efficiently by the beneficial arthropod that today the scale is only in a few places of importance. The method of integrated plant protection was also to a large extent developed by the Landesanstalt für Pflanzenschutz. Now there exist guide-lines as to integrated plant protection in apple cultivation, according to which almost 1000 hectare of fruit plantations are successfully treated. The investigations on integrated control of harmful organisms in the field of small fruits have already begun. Virus diseases which is your specific scientific subject also attacked our plantations. Here the sharka spread more than anywhere else in the Federal Republic. On one of your excursions you will have the opportunity to see such a serious infection of a plum plantation near Herrenberg. Last Year apple proliferation caused by mycoplasma-like organisms inflicted considerable crop losses in a lot of apple plantations because of small fruits. At present both these diseases are troubling the Plant Protection Service in Baden-Württemberg. We are grateful that you are dealing on your symposium also with the diseases mentioned above and hope you will help us to get a little closer to solution of the problems.

But you are also going to have the possibility to get to know some of the beauty of our Land. Already this meeting-place, Heidelberg, is an agglomeration of famous cultural monuments and is again and again visited and admired by guests from all over the world. On your excursions you will also see other parts of our Land like the region of the Neckar near Heilbronn or the famous Schwarzwald (Black Forest) which has always banned the visitors with its beauty. So I hope that in addition to a progress in your scientific work you will take back home with you also a pleasing remembrance of Baden-Württemberg, the country which is that much favored by nature and so rich of all kinds of beauty.