HIGH FLYERS THINK TANK

Emerging diseases – Ready and waiting?

The Shine Dome, Canberra, 19 October 2004

Group C: Plant health

Rapporteur: Dr Andrew Geering

I am going to start off at the end, with our final conclusions in the risk matrix.

Risk matrix
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Surveillance we thought was being done poorly in Australia.

Prevention in the past has been high through a very good quarantine system, although we felt that this quarantine system was under great threat from globalisation, bulk imports of ornamentals or flowers, et cetera. So we saw our prevention grading from high, previously, to maybe medium in the future.

We thought our responsive capacity was quite high; and our recovery, medium for pathogens of agricultural systems but exceedingly poor for pathogens of natural environments, many of which cause changes to environments, the pathogens.

I am just going to elaborate on each of these points now.

Surveillance
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Generally the surveillance is neither systematic nor extensive. There is a lack of field pathologists. Most of the major incursions in the past have been made by members of the general public – farmers or farm consultants. There is an absence of good knowledge amongst these sectors of the community about some of the quarantine threats.

A lot of decisions that are made about the importation of commodities are about managing risk, and there is a lack of good risk models for plant pathogens, plus not only an absence of good risk models but also a lack of good import data. If you put rubbish data into a model, no matter how good it is, you will get a rubbish answer coming out of that model.

In particular, there is not good knowledge about environmental factors that drive spread of the pathogen, what the potential geographic range of the pathogen could be if it did get into Australia, and what the risks of entry are.

There is also a lack of good knowledge of pathogen variation and also of host resistance.

Surveillance
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As is coming out as a common theme in the talks that we have seen so far, surveillance starts in neighbouring countries, that being probably in South East Asia, and we need a good knowledge of what pathogens are at the doorstep. This can be either through collaborative projects or also aid in those countries in empowering the pathologists there to better know what pathogens are found in those countries.

There is a lack of an Animal Health Laboratory Geelong equivalent for the plant world. There is a lack of good containment laboratories where exotic pathogens could be worked on for the development of diagnostic tests or investigations of biology.

We are very much behind the veterinary world in terms of routine screenings for knowns and also unknowns, and random sampling systems. And there is a need for some kind of remote surveillance which could either be various types of traps – for example, pheromone traps can be used to attract in target insects, or light traps can also draw in insects, or spore traps – or satellite or plane surveillance to look, for example in forests, for emerging diseases. Of course, any aerial surveillance needs to be ground truthed by people on the ground verifying and interpreting what can be seen from the air.

Response
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In terms of response, surveillance is the key. The response is really dependent on how early the pathogen is detected. The feeling of the group, from recent incursions, is that the response has been rapid and aggressive and quite successful when the detection has been early enough, but once the horse has bolted there is very little that can be done.

There is a problem, in that often there is the expertise within Australia to make a diagnosis but in the past there has been a slowness in identifying where this expertise is located. There is therefore a need for a national, coordinated approach.

Probably more so than in some of the other pathology fields, there is an erosion of discipline strengths. We are getting down to single-digit numbers with some of the disciplines in some states. There is a problem of a firefighting mentality, responding to industry needs and jumping from one problem to another, and when a particular discipline isn't needed, allowing that discipline to erode. There is nothing better to illustrate this problem than with the citrus canker problem in Queensland at the moment, where we are down to two plant bacteriologists – of whom one would be killed if a bomb were to fall on us right now! (I am not suggesting that, but that is how dire it is.)

Response
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Also, the response is limited by a lack of supporting legislation, in that sometimes you are hampered in an ability to track sources of an incursion.

Prevention
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Prevention has been good through quarantine, but is under threat from globalisation and bulk imports.

Generic tools are becoming available to control pathogen groups, for example RNA interference for plant viruses, but more research is needed for other pathogen groups such as fungi and nematodes.

There is a need for good education packages for the army of community people – farmers, farm consultants et cetera – to identify diseases.

There is a need for information on chemicals that might be useful against key targets: rates of application, efficacy, considerations of safety of application, for emergency registrations.

Prevention
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There is a need for pre-emptive breeding for resistance. A good example of this is sugarcane – a centre of diversity for this plant species is in New Guinea – so not only a centre of diversity of the plant germ plasm but also the pathogens and through collaborative research efforts to at least get some knowledge of what resistances were available. Maybe through use of molecular markers this resistance could be introduced into our germ plasm without even having to screen against the pathogen.

There is also a need for managed deployment of varieties – avoid monocropping or two-cropping with two varieties – through a mixture of genotypes with different resistances. It is a means of slowing spread of a pathogen and also preventing establishment of virulent strains.

Recovery
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Recovery: maintenance of discipline strength is critical.

We need to remain vigilant with quarantine and maintain an awareness of new strains that are emerging, for example the issue with the late blight of potato that John Manners mentioned in his talk.

You could go a long way to developing this knowledge by having a knowledge of the pathogen and also the host in the centre of diversity. We need research on new sources of resistance and fungicides et cetera.

Discussion

James McCarthy – I would like to support your view about maintaining discipline strengths. It is an issue that certainly was raised in our group as well, in the Human Health area, that there are so-called niche or small areas of laboratory science, for example in human microbiology, which are basically being threatened by the way the university systems work, in the way the health is now being delivered. A lot of the pathology is now being privatised and there is a dearth of qualified Human pathologists as well, because of the way the market is driving things. I think that is certainly an emerging threat for response and diagnosis in human infectious diseases as well.

Martyn Jeggo – A thing that surprises me that hasn't been mentioned so far, and I think it particularly applies to the plant world, is that in effect Australia is seven countries, each with a set of legislation, each with different ways of implementing things, each with different priorities, and very often a competing element. We are all talking nationally here about how we manage emerging diseases. Nobody seems to be mentioning the issue that the current system we have got, of the States, may be impeding our ability to respond to the risk from emerging diseases. In the animal world it is not quite so bad, but in the plant world I see that that could be quite a major issue because everything is so different in the States and you are competing. Would you like to comment on that?

Andrew Geering – Well, we are a bit slow off the mark but we have caught up a bit with the animal world now that we have the Office of the Chief Plant Protection Officer and we also have Plant Health Australia, the equivalent of Animal Health Australia. And now, with recent incursions, especially while it is still considered an incursion into Australia as opposed to the virus being now endemic and it is a matter of States eradicating a disease, the response is managed by the Office of the Chief Plant Protection Officer, Graeme Hamilton.

There are national protocols for diagnosis being developed for various pathogens such as karnal bunt and I am doing maize dwarf mosaic virus in my office at the moment, and stuff like that. So we are catching up. But we were slow off the mark in the beginning.

Aileen Plant – I would like to support what Martyn just said. In human health, we are definitely working with nine jurisdictions, I reckon, and it is terribly difficult when you get something new. The Commonwealth has got legislation around quarantine but it has neither legislation nor the responsibility within the States. One of the first things to happen if we get an outbreak – just say we even got one case of variant CJD in a human – is that the responsibility for dealing with it will still remain within that state, but the impact will be national. I think we could do a huge amount better in our collaborations between the States and Territories, but it will take a lot of work.

Jim Peacock – Just a comment while we are waiting for the next question. I was thinking about this problem of money. Just with the five major crops in Australia we probably lose something like $1 billion a year, every year, in lost yield because of disease. We just don't get that message across effectively in terms of trying to argue for increased resources to better fight those diseases and reduce that loss. They are big losses for us.

Bryan Cantrell – I am from the Queensland Department of Primary Industries and Fisheries. We did discuss that issue in the plant biosecurity group, about whether or not we would be better off with one national government in Australia. My response there was along the lines that, true, we have got seven countries in Australia – but, Martyn, we really do collaborate fairly well these days. I think the exception is in terms of how responses are handled.

I think the big difference still comes, though, in terms of market access. This applies particularly in southern Australia. Whenever there is an outbreak of anything in one particular State, the southern jurisdictions are very quick to put on trade bans. I guess we in Queensland suffer more from that because we tend to get, on average, more incursions and more of our tropical products go down south. So we feel the impact of that. But again the Domestic Quarantine and Market Access Working Group does have a fair incentive to protect the grain industries. There are a lot of industry demands, obviously, in other States to keep things out. So we are working on that part of it, but I think progress is fairly slow.

In terms of the response, I think even though we do have seven pieces of legislation they are all very similar, and because now, as Andrew said, we do work closely through the Consultative Committee on Emerging Plant Pests, we are meeting regularly by telephone and we know each other fairly well and there is much better rapport at the national level now and much better cooperation.

Jim Peacock – I am glad to hear that, but I still think that having one rather than seven trying to be one might even be better still.

John Manners – Could I just make one comment on the plant discussion. It is around natural environments. There was a general view that this is an area that is very easy to ignore, and I think it not only applies to the plant world; it applies to the native fauna as much as it does the native flora. We are actually responding here very much to the economic drivers but we shouldn't really forget that we are very, very poor in our knowledge and understandings of diseases in natural environments. Some examples were discussed where they could be quite catastrophic on eucalypt forests, for example. We have seen it in the past with yarra forests in Western Australia, where diseases have very major impacts on local, regional ecosystems.

Jim Peacock – Did you regard weeds as a disease, John?

John Manners – No.

Jim Peacock – That is another whole area for plants.