WELCOME ADDRESS BY CHAIRMAN ISHS WORKING GROUP OF FRUIT TREE VIRUSES

Before I start to talk about NAFTA and other unpleasant issues, let me thank the hosts for inviting me to this meeting! As a tree fruit virologist, I always look forward to these symposia as a very unique opportunity to exchange ideas, to challenge and be challenged, and maybe to contribute a grain or two to progress - whatever that is! This morning, I'll try to do my best to fit into that pattern.

"When in Rome, do as the Romans do" is a well-known slogan. To most people, it is a call for uncritical conformity. Yet our hosts are living testimony to the fact that this interpretation must be a major misunderstanding!

'Tua res agitur' is another famous phrase that Latin students have to learn in high school. In my own free translation, it means "All public business is also your business", or, as the Roman emperor Marcus Aurelius put it, "What's good for the hive can't be bad for the bee".

So when I looked at the proposed theme for this opening address, I began to wonder about our hive and about all you bees!

Traditionally, we as tree fruit virologists have worked within the confines of our country's national science or horticultural policy (if any!). Much of our work with tree fruit viruses has been preventive, related to national import and export policies and to plant quarantine.

With the advent of major trading blocks in the world, this is about change. We have no idea where these changes will take us, but we will be part of the process, whether we like it or not. Our two major challenges will be to cope with the increased commercial movement of potentially virus-infected planting material and with the reluctance of our politicians to maintain the traditional plant quarantine restrictions which affect such movement within and between trading blocks.

For nurseries in Canada and the Northern U.S.A., the North American Free Trade Agreement (N.A.F.T.A.) eliminates many of the former trade barriers. These nurseries are tempted or are already planning to move major parts of their operation to Mexico, where climatic conditions are more favourable and wages are lower. Some of the nursery managers hope that all trade barriers will fall and that the plant quarantine restrictions will be eliminated at the same time. They are finding support among politicians who simply don't understand the dangers of unrestricted movement of untested plant material between or within the future trading blocks.

At the same time, we also see less barriers against shipments of fruits and vegetables from Mexico and Latin America. More and more stone fruits and pome fruits are crossing the borders. This raises the spectre of viruses being brought in and spreading in the U.S.A. and Canada.

Today, we in North America are concerned mostly about sharka and apple proliferation which are common in Europe and which can spread rapidly. Sharka has already been introduced into Chile. We do have the necessary testing and therapy methods to prevent the spread of sharka and - to a lesser degree - proliferation. But do we have the political will to stop them if they come in from a Mexican nursery? Or from a Chilean nursery, a few years down the road, when the N.A.F.T.A. territory is extended?

You in Europe and the other fruit-growing countries are likely wondering whether some of our indigenous North American vector-carried viruses and virus-like agents may reach Europe. We only know the vectors for a few of them. We can only guess at their mobility under different environmental conditions.

Let me illustrate some of the new challenges with an example from the N.A.F.T.A. area. By choosing potatoes, I hope to avoid stepping on tree fruit and small fruit researchers' toes! But the challenge is really the same for all vegetatively-propagated crops.

Canada has a major potato-growing area along the East Coast, in the provinces of New Brunswick, Nova Scotia and Prince Edward Island (P.E.I.). With considerable help from Canadian Ministry of Agriculture, we have managed to make and keep much of the area free of viruses. This has been the basis for a thriving and profitable seed potato export industry to the U.S.A. and other countries in the Americas.

In 1984, the highly destructive necrotic (N) strain of potato virus Y appeared in Nova Scotia and continued to spread in spite of control measures. Consequently, all seed potato export was halted and a testing program was initiated, based on a test which relied on symptom expression in tobacco plants that had been pre-infected with a mild strain of PVX. It is not a very high-tech system, but it was the best available at the time. PVY, after all, and for readily understandable reasons, is not a favourite of the serologists! Some of the tests were conducted in Nova Scotia, others in the central lab in Ottawa.

When tests of seed potatoes from adjacent P.E.I. began to show positive results and exports from there were halted as well, some disgruntled growers initiated court action to test the validity of the export ban and the reliability of the testing method.

Meanwhile, the U.S.A. and Mexico had banned the import of all seed potatoes from the PVY - N - affected provinces in order to protect their own industries. The N strain had until then not been discovered in either country. The losses to the Canadian seed potato industry amounted to tens of millions of dollars.

The whole situation changed again when it was found that tests conducted with the same potato source material in Nova Scotia and Ottawa gave different results, and when the N strain was detected in several locations in the U.S.A.

Once the details of the test methodology were standardized, the results showed that the N strain had apparently not been present in P.E.I. The detection of the strain in the U.S.A. eliminated the reason for the import ban against Canadian seed potatoes and the border was opened again, while the Mexican border remains closed.

The case is now before the courts, where it will undoubtedly create more heat than light.

I have described this case anything from this case, it is this: we are faced with a vast proliferation of elegant and highly sensitive laboratory strains of tree fruit viruses. As we will discuss during this symposium, and as we have seen in the Pacific Northwest with NRSV in cherries, specificity in the lab or greenhouse does not always correspond the pathogenicity or specificity in the field. Yet from the practical disease control and preventive quarantine point of view, our major need is for methods that give uniform results in field situations. Our credibility depends upon them!

At the same time, we are working with a legal framework (permits; indicator methods and lab tests; border control) that was designed primarily to protect national industries, rather that facilitate international trade. The NAPPO office has tried to develop new guidelines and especially new test methods, but the governments have so far been unwilling to implement these.

The second lesson concerns the very unfortunate psychological side effects of the PVY - N virus situation and the threat of other similar court cases elsewhere. It is becoming obvious that researchers and quarantine officials are increasingly reluctant to work on quarantine and regulatory matters at all, at a time when such work is needed more urgently than ever. Yet if we lose this dedication to structuring our plant health activities, we may well lose the whole justification for our profession!

From my point of view, there are six areas that require increased efforts from all of us:

1. Development of almost-universal virus detection methods based, for instance, on DNA probes.
2. Development of detection methods that are simple, virus-specific and economical.
3. Better identification of the area of occurrence of major tree fruit viruses.
4. Focus on vectored viruses that present a major potential threat to areas where they do not occur.
5. Agreements on international testing standards which can be used in exporting as well as importing countries.
6. Better cooperation between international (FAO, EPPO, NAPPO) and national plant quarantine agencies.
7. Continued development of integrated virus-free nursery, certification and production systems.

I am coming back to the lesson to be learned from classical Rome, and from Canada's potato war: tua res agitur! Translated into a message for us, in 1994, it means that we have to work harder to maintain the close connection between the basic scientific work and applied field, between the researcher and regulator.

Let's make sure that the bees are aware of the hive, and that someone bothers to hold to hive together!

That is, after all, why we came here!

Thank you, Antonio Quacquarelli and Marina Barba, for organizing this symposium, which promises to be the most popular we have ever had.

And thank you for listening so patiently!


Jurgen A. Hansen
Chairman ISHS Working Group
Fruit Tree Virus Diseases