DANIEL McALPINE MEMORIAL LECTURE 1991

Plants, diseases and pathologists in Australasia – a personal view

J. Walker

5 Cook Street, Baulkham Hills, New South Wales 2153 

Introduction 

It is just 20 years since the Australasian Plant Pathology Society decided to establish this lecture series and 101 years since Daniel McAlpine was appointed as the first plant pathologist in Australia. Over the next 30 years, he published over 200 papers and books dealing with all aspects of the subject, from disease control methods to taxonomic studies of rusts, smuts and other fungi and from field diseases of cereals, citrus, grapes and stone fruit to post-harvest disorders of apples and other produce. His biographer, Mr Stanislaus Fish (1976), noted that McAlpine also had a major influence on the teaching of biology and plant pathology in Australian universities.

McAlpine was a complete plant pathologist, an all-rounder whose work ranged widely over many aspects of the subject. However, plant pathology and plant pathologists have changed much since McAlpine's day. The subject and its component disciplines have expanded so much that it is now difficult for one person to keep up with the advances in knowledge in even one of the branches of our science. Some of the disciplines that go to make up present-day plant pathology are shown in Table 1. Specialists in many of these disciplines are now employed to take an active part in unravelling plant disease problems. Several previous McAlpine lecturers have discussed detailed aspects of their speciality and I considered various taxonomic problems in the fungi as possible subjects. However, I rejected the fungi in favour of a more general discussion of some aspects of plant pathology in Australasia. The matters that I have chosen cut across all the specialized disciplines and are of importance to all who work in plant pathology, whether they be in research, teaching or advisory positions, whether they be bacteriologists, epidemiologists or molecular biologists. The title chosen indicates the three main areas that I wish to explore – plants, their pathogens and the diseases they cause and the people who work on them. I must stress that the views that I shall give are personal and any resemblance to the opinions of other pathologists is purely coincidental. Moreover, I must apologise to my Rydalmere colleagues as it is from working with and observing them for so many years that some of my opinions have developed. Many of the examples and statistics that I give are Australian, as they were more readily available tome, but I think that at least some of the general conclusions drawn from them will apply to New Zealand as well. 

Plants

On this earth, the most basic manufacturer, converting primary energy into organic matter, is the green plant. 'They toil not neither do they spin" (Matthew 6.28) but their silent, motionless activity is the single most important biological process going on around us. Plants are the source of all food and all timber; they purify the air, help recirculate the water and stabilise and enrich the soil. The flora is the milieu that houses and supports all human and animal life and the micro-organisms that play such an important role in the recycling processes of nature. Green plants are the largest, the most cost-effective, the least polluting, the most valuable and, at the same time, the most over-looked and under-rated of the manufacturing industries. Plants are just there! They are completely taken for granted by most people.

There are three layers of plants to be considered. First there is the flora native to the region. As far as species numbers and diversity go, this is by far the largest component of the Australian plant population (Table 2) and these figures are for vascular plants only and do not include the vast array of cryptogams. At the family level, the Australian flora is not much different from the flora of the rest of the world. As Barlow (1981) has said in his informative essay in Volume 1 of the Flora of Australia "Almost all the angiosperm families in Australia occur widely elsewhere. Conversely. almost all the larger families of the world occur in Australia." However, at the lower taxonomic levels of genus and species, a different picture emerges. To quote Barlow (1981) again "The flora is certainly unique in the sense that a very high proportion of its species are endemic to the continent. It is also distinguished by the fact that two large genera, Eucalyptus and Acacia, between them, dominate almost all the plant associations of the continent'.

The New Zealand flora contains about the same number of species as that of Tasmania and there is a marked similarity in both areas in the Antarctic or Southern Oceanic elements present. The uniqueness of the Australian flora is at genus and species level but its continuity with the rest of the world at family level are of some significance for plant pathology, especially when we come to consider exotic diseases and plant quarantine.

Overlying the native flora, and in varying degrees intrusive upon it, is the flora of introduced naturalised plants. This is a much smaller group than the native plants but the deleterious effects that many have as invasive weeds have been enormous. In this category, there are also some crop, pasture and ornamental species that have escaped and become self-perpetuating. Some plants in this group can act as carry-over hosts for pathogens attacking crop species in the same family (for example, various cruciferous weeds, some naturalised grasses and many others) and some weeds species are candidates for biological control investigations.

The third layer of plants (Table 3) contains the cultivated species and almost all are introduced. This is the major group of food plants, introduced pasture and softwood timber species as well as a wide range of ornamental plants covering many botanical families. Botanically, this is quite a diverse group, containing over 400 species cultivated for food, fodder, fibre, oil and timber, plus 50 common and at least 2000 less common species grown as ornamentals. Most current scientific effort and expenditure on Australasian plant pathology is devoted to cultivated plants.

Having identified these three plant groups, it is of interest to lock at the land area they cover (Table 4). Crops take up less than 3%oftheland area in Australia and introduced sown pastures and grasses about another4%. More than 50% of the total area is grazed and this figure includes land that at any one time is fallow or lying idle. Native forest is present on only 5.3% of the land area and plantation forests, which include both introduced and native species, make up only a fraction of one percent of the Australian landscape.

Finally, in this set of plant statistics, what are plants worth to Australia? There are various ways of estimating worth, one of which is monetary value, and I have shown in Table 5 the figures given for the agricultural and livestock industries in the latest issue of Year Book Australia (Casties 1991). The figures for l984–85give some idea of seasonal and other variations. The total monetary value of crops in l988–89 was nearly $10 000 million. It is appropriate to include the livestock industries as well, as they are totally dependent on plants. Their value is about $13 000 million, giving a total for all agricultural and livestock commodities for 1988–89 of just over $23 000 million. None of these figures include a monetary value for forestry or the native flora. It can thus be seen that, in Australia, the plant based industries are worth a considerable amount of money. However, as stated previously, the value of plants cannot be measured by money alone. Their various roles in the air and water cycles, in soil stability and nutrient recycling, as habitats for animals and microorganisms, their aesthetic and social values – all these cannot be readily assessed in monetary terms and much more fundamental value systems come into play.

It is apparent from the data (Tables 1 to 5) that the vast majority of plants in Australia, covering most of the land area, receive little attention from plant pathologists. Most expenditure is on crop species, but even so there are still many crop, pasture and forestry disease problems that have never been properly investigated. Of course, it is necessary that we give full attention to the crop species but as this always uses up most of the available resources, the majority of other plants are neglected from the disease point-of-view. I will return to this when diseases and pathogens are considered, but first there are two other points about plants: 

(i) in my experience, and rather surprisingly, plant pathologists often tend to neglect the plant as such. Their attention turns more towards the pathogen, the disease and environmental factors or to microscopic and sub-microscopic details of plant cells and of their biochemical and genetic properties. Often, their general botanical knowledge is poor. This is a serious handicap to plant disease work as a sound knowledge of the plant in health is essential if we are to be competent students of the diseased plant. This applies not only to its external morphology and internal anatomy but to its cultural and environmental requirements as well. Many problems presented to pathologists are either of non-parasitic origin or have cultural or environmental predisposing factors and, for their solution, require a thorough knowledge of the conditions under which the plants are growing and of the treatments they have received. Whilst important for all plants, this is especially important in the case of perennial species, where long term investments are involved.

(ii) All pathologists require some familiarity with plant classification and plant biogeography. A good knowledge of the relationships between species is an enormous help when considering such matters as the potential host ranges of exotic pathogens, the safety of proposed biological control agents, epidemiological matters involving alternate and carry-over hosts and a wide range of other problems that arise every day in disease control, quarantine and trade. In quarantine and trade especially, a knowledge of the biogeographic relationships of exotic floras to the Australasian floras is very important if exotic disease risks are to be assessed accurately. Various other plant facts will emerge during the discussion of diseases and pathogens. 

Diseases and pathogens

Unlike diseases of humans and animals, plant diseases make little emotional impact on our society. The plight of a koala with an eye infection is much more a matter of public sympathy and support than the canker and leaf diseases of the eucalypt on which the koala depends for its life. This widespread attitude leads to the perception by society that animal diseases are much more important than plant diseases, if indeed plant diseases are thought of at all. This poor social image of plant disease has important practical consequences. For example, the stringent quarantine provisions for exotic diseases of animals and the swift and dramatic action taken when an outbreak of such a disease is suspected are in marked contrast to the indecision that I have observed in the past in the handling of some newly introduced plant diseases. If we cared as much about diseases of plants, on which animals depend entirely, as we do about the diseases of the animals themselves, then I feel sure that our response to exotic threats to plant health would be much more appropriate. Certainly, we all need to educate the decision-makers about plants as our basic life-support system if we are to have sound policies to protect the plant health of the country. I do know of a few people who have spoken their mind on such problems in the past but this educational role should be undertaken by all pathologists.

How many plant diseases are there in Australia? And what is our knowledge of the identity, host range and distribution of plant pathogens? I will deal only with parasitic diseases but it must be remembered that non-parasitic conditions resulting from environmental factors such as frost and drought, nutritional excesses and deficiencies, physiological and genetic disorders, and pollution of soil, air and water by a diverse range of chemicals can all cause major damage to plants. Indeed, frost and drought in some seasons cause more losses than the parasitic diseases. These conditions themselves could be the subject of a separate lecture.

At present there are no up-to-date counts of the numbers of pathogens in various groups recorded and reported from Australia and New Zealand. From recent listings of nematodes (Khair 1986), bacteria (Moffett 1983) and plant viruses (Büchen-Osmond et al. 1988), from published lists of diseases for various States and from herbarium resources at Rydalmere, some figures have been prepared showing the approximate number of host/pathogen combinations and of pathogen species in Australia (Table 6). The fungi are by far the largest pathogen group, accounting for 80% of the parasitic diseases recorded and making up over 90% of the recorded species of plant pathogens. The plant-associated nematodes are the next most numerous and root-knot nematodes are responsible for many of the host-pathogen combinations recorded for them.

As partial comparison between countries, comparable counts for fungi have been made from the recently published list of plant fungi in the United States (Farr et al. 1989). In Australia, there are about 15 000 host/ pathogen combinations reported, of which 12 000 are plant/fungus associations, occurring on over 3000 plant species, in about 14 000 genera. By contrast, in the greater USA, there are nearly 78 000 plant/fungus combinations on 8709 plant species in 1912 genera. If we compare these figures with the total plant populations of the two countries (Table 7), it can be seen that the density of fungus/plant associations reported in the USA is about five times that reported in Australia. I have not attempted to distinguish records on crop species from those on native plants in each country and it has not been possible to prepare similar comparisons for other pathogen groups.

A recent article by Hawksworth (1991) has some disturbing estimates of numbers of species known in various groups of organisms. In brief, his figures indicate that the known fungi (about 69 000 species) represent only about 5% of those that exist, an estimated total of about 1.4 million species. The comparable figures for bacteria and viruses are 10% and 4% known, respectively. By contrast, the figure for vascular plants is 81 %. I recommend that you all read this thought-provoking article and ponder the implications for biology as a whole and for plant pathology in particular. If Hawksworth's estimates are approximately correct, and there is quite a lot of supporting evidence, then, at the present rate of discovery and description of new fungal species, it will take another 844 years to compile the remainder!

These considerations lead on to several points:

(i) It is apparent that Australia is still greatly under collected as far as the fungi go and I have little doubt that this applies to all groups of plant pathogens. The responsibility for recording our plant pathogens falls largely on plant pathologists. Ours is a specimen-based discipline and all our investigations begin with observations on diseased plants. Although the position has improved slightly in recent years, it is unfortunate that the collecting instinct that used to be so strong in all biologists seems to be almost extinct in some plant pathologists, with several notable exceptions. However, it is only with a great increase in the collection of specimens and in the numbers of specialists in the various pathogen groups that the deficiencies in our knowledge referred to above will be remedied in a reasonable time. Only records based on specimens and their associated cultures, antisera, and other materials important in various pathogen groups are capable of being authenticated at a later date and it is nothing short of scientific vandalism when pathologists discard specimens and other materials that are the basis of their work or that they have examined for diagnostic purposes. There are now available, within many groups of plant pathologists, herbarium and culture collections where specimens and cultures can be lodged and permanently retained. In this regard, special support should be given to the National Collections of Plant Pathogens located at Burnley, Indooroopilly and Rydalmere and efforts made to have incorporated in the National Collections some other pathogen collections of importance, especially those at the Waite Institute. Whilst all components of the National Collections currently need increased support, the nematode and virus collections are in particularly bad shape at present.

The importance of retaining original material for future reference and study cannot be overestimated. Resolution of some trade and quarantine problems often depends on access to specimens and cultures collected many years earlier and it is only with substantial collections that accurate data on identity, host range and geographic distribution of pathogens can be obtained. Moreover, with recent advances in molecular biology, and the ability to extract and identify DNA from dried collections, the value of herbarium specimens of all pathogen groups for identification purposes has been greatly increased. For these reasons, I exhort all to be aware of the importance of the specimens with which you work, to treat them with respect and to lodge them with a plant pathology collection or pathogen specialist, or with one of the branches of the National Collection of Plant Pathogens.

It is also apparent that, in the future, we can no longer rely on the haphazard collection of plant pathogens by chance as has happened so often in the past. Many more organised field surveys of all plant groups must be carried out and to achieve these staff numbers will need to be increased. There is increasing pressure for accurate information on disease distributions in Australia and quarantine and trade concepts such as area freedom cannot be achieved without a thorough knowledge of our diseases, their host ranges and geographic distribution.

(ii) Secondly, I feel that there has been a decline in the diagnostic ability of some plant pathologists. This appears to be due partly to the decline in interest in the general collection of diseased material mentioned already and partly to increased specialisation, either at the crop, pathogen or discipline level. To a certain extent, this has been offset by the development of multi-discipline groups, where the combined resources of several experts can now be used to solve problems much more efficiently and at much greater depth than before, when much reliance was placed on the breadth of knowledge of one or two people. The diagnostic process is the point at which all the expertise and experience of a pathologist can be brought to bear on solving a problem, and it is unfortunate that it is often rushed and given a low priority. The large deficiencies in our knowledge of plant diseases in Australia and the quality of our service to the primary industries can be improved only by a greatly increased commitment to accurate diagnosis.

(iii) Thirdly, while we know many pathogens by name, we often know very little about their biology and what they are doing when they are not obvious to us as pathogens. The recent finding in South Australia of the teleomorph of the wheat eye-spot fungus is just one example of what can be discovered in the area of pathogen biology by careful work. Some species concepts are also so wide as to be almost useless. For example, the name Colletotrichum gloeosporioides as commonly used in plant pathological literature refers to such a large group of different organisms that it conveys virtually no information about the identity of the fungus present or its properties in any particular case. Again, to refer to a bacterium as Pseudomonas solanacearum is quite insufficient for any accurate decisions to be made about it in, say, a particular quarantine interception. Inadequate species concepts and the occurrence of variation at several sub-specific levels are not only matters for specialist study, but are of immediate practical importance in most aspects of our work. Amongst other things, we may need to reassess some of the risks involved in the movements of plant material and of living cultures of micro-organisms. A policy that says we already have pathogen species A in this country and so there is little or no risk if we introduce it again could easily lead to the introduction of damaging pathogenic variants of the species. A similar situation exists with the movement of plants and pathogens from one part of Australia to another. Moreover, proposals to release organisms for biological control purposes without detailed knowledge of their identity, biology and current distribution should not be contemplated.

(iv) Fourthly, with a few exceptions, diseases of native plants and of many introduced non-crop plants have been largely neglected in Australia. As mentioned above, this has mainly been neglect by default, as most resources are used up on crop and major timber species. There are many reasons why this situation must be remedied and I will give a few examples. In my last two years at Rydalmere, I spent a lot of time trying to unravel some problems raised by the United States Department of Agriculture about Australian grass seed exports to the USA. These concerned several diseases, mainly smuts on native grasses, which the USDA said were present in Australia and which constituted a potential threat to the USA if imported. Because of these problems, grass seed exports were held up. By chance, I had worked on several of these smuts over the years and was able to show, to the satisfaction of the USDA, that all but one did not constitute a risk. The one remaining difficulty concerned the native smut Sorosporium cryptum which occurs in eastern Australia on several native species of Panicum. Little is known of the biology and pathology of this smut and work is still in progress at Rydalmere on its life cycle and ability to infect cultivated Panicum spp. Until this problem is resolved, difficulties remain with the export of grass seed. This is a good example of the direct relationship between lack of knowledge of a native disease and an international trade problem.

While dealing with grasses, it must also be mentioned that, although of considerable importance to the grazing industry over nearly 60% of the continent, and with a potential for improvement and much greater use in and areas, practically no studies have been made of the diseases of native grasses, apart from the description of some fungal parasites.

Another aspect of this problem is our inability, in many cases, to provide data on diseases of Australian native plants to those interested in growing them. Eucalyptus spp. have been grown overseas since the early 19th century and in recent years there has been an increasing interest in the cultivation of a wide range of native species. Many are now being sought as ornamental plants, both in Australia and overseas, and surveys carried out in Victoria and other States by Pascoe and Sutton (1987) on a range of species have revealed many previously unknown parasitic fungi and highlighted the need for much more intensive work in this area. Australian Acacia spp. provide another example with the use of nitrogen-fixing trees to produce protein-rich seed for human consumption receiving recent attention (Zimsky 1991). The author states 'The Australian Acacia spp. may hold the greatest promise as a nutritious tree food source for arid regions' and these trees have considerable potential for human food production in the drier parts of Africa. Already locally grown Acacia holosericea seed is being incorporated into diets in Niger and it is highly likely that other Acacia spp. will be used for similar purposes. Other examples could be given. However, one fact stands out. When we think of the constant use we make of overseas information on diseases of plants native to other countries, it is obvious that we have a responsibility to provide similar data about our plants for overseas users. The amount of pathogen and disease information available overseas about genera such as Triticum, Trifolium, Prunus, Rosa, Citrus, Pinus and many others, on which we draw constantly, far outweighs that available in their native country for such genera as Acacia, Melaleuca, Callistemon, Grevillea, Leptospemum, Lechenaultia and others.

Many other reasons could be given for studying diseases of native plants, including their significance to the Aboriginal people, their importance as food and shelter for native animals, the light that they shed on the evolution, classification and biogeography of plants and their parasites and, not least, the economic potential they offer for Australia.

I will mention only one point on exotic diseases. Just as Australia is underexplored for plant diseases and pathogens, so are many other countries. Moreover, as already noted, in many groups of micro-organisms, the described species probably represent only a small proportion of those that exist. There is thus a strong possibility that there are as yet unknown or undescribed pathogens in most countries, some of which could constitute a real quarantine risk for other countries. Indeed, 30 years ago, this was the case for some of the Central and South American pathogens of Myrtaceae which are now known to attack several species of Eucalyptus and other Australian genera. This possibility must be taken into account in all quarantine deliberations, at least partly by a concept of high risk plant groups.

There are just two other aspects of pathogens and diseases that I would like to mention briefly. The losses caused by plant diseases are difficult to estimate but some idea of the scale of possible losses can be gained from figures prepared by the United States Agricultural Research Advisory Committee (Table 8). It can be seen that, overall, the estimated losses due to plant diseases exceed 10% of potential crop production. Regardless of how accurate such statistics are, it is obvious that losses are considerable and there is no reason to doubt that the position in Australia is any different. I would ask you to keep that figure of 10% in mind.

Finally, in this consideration of pathogens and diseases, there is the matter of control measures. There is now considerable social pressure, backed in many cases by scientific evidence, for a reduction in the amount of chemicals being put into the environment. On this point, I am grateful to Professor Brian Deverall for some recent comments. He attended the 1991 International Plant Protection Conference held in Rio and representatives of the chemical industries attending reported that big changes are imminent. These are due largely to pressure from environmental groups, and particularly from the Environmental Protection Agency in the United States, to cut down on the use of chemicals. As a result, large cut-backs in the production of agricultural chemicals are forecast for the near future and, because of the reduction in income this will cause, some of the biotechnological projects of these companies will also be reduced. These changes will have important consequences for plant pathology. First, in disease management, there will be much less reliance on a chemical fix and much more on the manipulation of biological and environmental factors. Already, some pest and disease management strategies make use of non-chemical means to reduce the damaging impact of insects and pathogens but this will need to be greatly extended in the future. This will necessitate a much more detailed knowledge of the biology of plants and their pathogens than we have at present and a return to many of the basic disciplines. The present decline in the teaching of these subjects in some universities may well need to be reversed in the near future. Secondly, the traditional employers of plant pathologists will have to fill this need and it is to be hoped that they will realise the opportunities offering.

So far I have dealt with some plant facts and figures and with some aspects of pathogens and diseases that I consider to be important to the work of plant pathologists. I would now like to discuss some aspects of plant pathologists themselves.

Plant pathologists

In 1966, I carried out a survey of plant pathologists in Australia and made some comparisons with overseas countries (Walker 1966). This year, I attempted a similar survey but the response was not as good as I had hoped and so the statistics shown are incomplete. However, for Australia, the data cover the majority of institutions concerned with plant pathology research and its associated advisory work, and with the teaching of plant pathology. For New Zealand, with its current reorganisation of public-funded science, I have been unable to obtain sufficient figures to compile a realistic table. Also, too few replies were received from overseas countries to make accurate comparisons with them.

In Table 9, the 1966 and 1991 survey figures are given. These show that 205 plant pathologists are currently employed, almost three-quarters of whom are in State Government departments. This figure agrees fairly well with a count made from the current APPS membership list. Although 433 personal members are listed, these include student and retired members and when these are subtracted, there are about 241 active pathologists listed for Australia at present. There are 30 listed from New Zealand and 14 in private industry in Australia. This table shows that the State Government organisations remain the main employers of plant pathologists in Australia, and indeed their percentage of the total has increased since 1966. Numbers in universities have fallen over the 25 year period, although I have not included post-doctoral fellows in the 1991 survey figures.

Although not shown in the table, the survey replies also indicated that there are about 180 technical scientific officers employed in Australia, as well as a smaller, unspecified number of assistants in laboratories, herbaria and culture collections and a range of clerical support staff. The technical scientific officers and the assistants are often responsible for the day-to-day running of projects and for doing much of the hack work involved in research and advisory programs. At best, they are fully acknowledged and take their proper place as full co-workers in projects and in the publication of results; at worst, some are treated rather as dogsbodys, with little use being made of their talents and enthusiasm. They play an important and often underestimated role in Australasian plant pathology.

How much the figure of 205 (241) for plant pathologists represents a real increase over the last 25 years is uncertain. Certainly, during that period, there has been an increase in the range of people who are called ‘plant pathologist’. For example, plant pathology positions in some institutions can now be filled by specialists in disciplines such as molecular biology, population genetics, virology and bacteriology who have had little or no formal training in plant pathology but who are nevertheless making a major contribution in the current multi-disciplinary thrust of the science. Moreover, from the comments that accompanied the figures, it is apparent that there has been a real and significant decrease in the number of forest pathologists employed in Australia within the last 10 years.

The universities surveyed provided figures of current numbers of students taking plant pathology as a major course and estimates of numbers expected over the next 10 years. Employing organisations (including universities) estimated the number of job vacancies in plant pathology over the same period. These figures are combined in Table 10. It can be seen that the number of potential graduates is about six times greater than the expected number of job vacancies, even allowing for a proportion of overseas students returning to their home countries for jobs there. If only post-graduate students are considered, the ratio is about two to one. Employing bodies commented that things were expected to become tighter over the next 10 years and there were also fears expressed by some universities both about the shortage of jobs for their graduates and the future fate of plant pathology and of some of its basic disciplines such as mycology in their institutions.

The survey also sought information on expenditure on plant pathology and the replies obtained are summarised in Table 11. As expected from the employment figures, State Government organisations spend the largest amount and also obtain the largest amount in grants. The total of just over$1 9 million shown is not complete but does cover most of the research and teaching activities in plant pathology that go on in Australia. It does not include quarantine, private industry or figures from a minority of institutions that regarded them as confidential.

There is just one more set of figures (Table 12) which bring together some of the data given in earlier tables. If we assume that losses due to plant diseases in Australia are of the same order as in most other countries, then an overall figure of 10% does not seem excessive. As we have seen, the total annual monetary value of crop production in Australia is in excess of $7000 million, but this figure does not include the forestry industry, the native flora or the $13 000 million livestock industry, totally dependant on plants. Combining these two figures, it can be said that plant diseases cost Australia at least $700 million per annum, and in view of the exclusion of several major plant groups, this is probably a most conservative estimate. The current survey indicates that we spend something more than $20 million each year on plant pathology research and teaching in Australia, which is about 3% of the estimated amount that crop diseases cost us and about 0.3% of the monetary value of crops, not including forestry, the native flora, pastures and the livestock industry. This seems a very small investment to me.

We live in a social, political and economic climate that is largely ignorant of, and indifferent to, plants, their diseases and the people who work on them. It has been said with some truth that scientists are politically and economically naive. But I suspect that the converse also applies – that many politicians and economists are scientifically naive and have little idea about either the technicalities of science or the climate and conditions necessary for science to do its job. However, in our society, it is politicians and economists who make the decisions, which can often have serious repercussions for scientific work. In recent years, in several organisations in Australia and New Zealand, we have had ample evidence of that. And it will continue in the future. It is thus essential for plant pathologists to ensure that the decision-makers are thoroughly informed, and indeed convinced, of the basic importance of plants and their diseases. In the widest sense, they must be shown that biological facts are inexorable and that true social, political and economic progress is possible only by working with the biological facts of life and not against them.

I have tried to explore a few of the biological foundations of our work on plant diseases and give a selection of statistics about pathologists and pathology. You will all be able to think of many aspects that I have not mentioned and you may well question the completeness and accuracy of some of the statistics. But this is where you, the Australasian Plant Pathology Society, come into the picture. From now on, our Society must take a much greater role in the promotion of plant pathology and its component disciplines in this part of the world. Article 2 of our Constitution states

‘The objectives of the Society shall be the advancement and dissemination of the knowledge of plant pathology and its practice, particularly, but not exclusively, in relation to Australia and neighbouring countries’ and one of the means to achieve these objectives mentioned in Article 3 is ‘by increasing public awareness of the functions and achievements of plant pathologists.’

I feel that, as a professional society, we have failed in this objective and have also failed to present any sort of convincing case to Governments or to the administrations of various institutions and departments of the importance of our work and the reasons why it should receive increasing support. For these reasons, I would like to put to you a few steps I think the Society should take to improve this situation.

1. Accurate data are essential. I thus suggest that the Society carry out a survey similar to that reported here in order to compile complete and accurate statistics on staffing, expected job vacancies and graduate numbers, expenditure on research and teaching and other matters as well as information on the achievements of Australasian plant pathologists, and on the contribution that our science makes to the economic and social life of the region. Who will do this? Well, there are already at least two special interest groups in the Society dealing with tropical pathology and nematology. Surely a third to gather such information and continually update it in the wider interests of plant pathology could be formed.

2. The Society must have a louder voice in Australasian science and promote the interests of plant pathology. We do have a voice through FASTS (the Federation of Australian Scientific and Technological Societies) but the general issues raised by the 70 societies that make up FASTS can bury many of the areas significant for plant pathology. Several of these have been raised in this lecture, for example

•the need for more intensive plant disease surveys; 

•the need for staff to carry them out and for pathogen group specialists to cope with the taxonomic and identification work they generate;

•the need for more basic biological studies of a wide range of diseases as an essential component of disease management programs to minimise use of chemicals;

•the vast discrepancy between the work to be done and the small number of new jobs available in plant pathology on the one hand and the large number of graduates expected who are the potential pathologists of the future on the other;

•the overburdening of scientific workers with administration duties;

•the discrepancy between the monetary value of plants and the losses caused by diseases on the one hand and the very small percentage of this value that is returned for research in, and teaching of, plant pathology.,

•the declining number of forest pathologists, and many other more general issues in areas such as trade and quarantine, conservation and the environment.

3. In order to try and achieve some of these ends, it is suggested that a permanent group be formed, under the auspices of the APPS, consisting of the Heads of Plant Pathology departments in all institutions where research and teaching of plant pathology is carried out in Australia and New Zealand. This group could meet at least once a year to discuss and prepare submissions on the many matters of concern to plant pathology. In the future, if we are to progress or even survive, we must show a much greater degree of co-operation at the personal, institutional, state and country levels than we have in the past. The botanists have given us a good example to follow. They have a Council of Heads of Australian Herbaria that meets at regular intervals to discuss matters of common interest and they have a strong voice in Australian science and a significant input to the decision makers. We need to do something similar, so that the significance of plant pathology in the social and economic life of this region is clearly seen.

And so, at the end, I come back to where I began. Present-day plant pathology is composed of many disciplines. Ability to manage plant diseases for the benefit of agriculture, horticulture, forestry, the environment and society as a whole can flow only from a rigorous practice of these sciences. All now work in intimate association to help solve the biological complexities facing us. Anything that interferes with this symbiotic relationship between these disciplines adversely affects plant pathology. Each of them is a science in its own right and, in this part of the world, may be represented by very few, or in some institutions, by only one, active worker. We are thus very vulnerable to disruption of any sort. We must get these messages across. You, as the plant pathologists of the present day, are the carriers of the discipline and its component sciences and you are thus its guardians. You all walk in the footsteps of Daniel McAlpine. It's up to you.

Acknowledgements

It would not have been possible to prepare this lecture without the help of many people who provided statistical and other information about the organization of plant pathology in the departments, institutes and universities surveyed. In particular, I must thank the following: Dr. S. Ashmore, Dr. A. Brown, Prof. J.F. Brown, Dr. R.F. Cerkauskas (Canada), Ms Mary Cole, Dr. R.N. Cruickshank, Dr. E. Davison, Prof. B.J. Deverall, Dr. A. Dubé, Dr. P. Gadgil, Mr. R.J. Gorringe, Dr. C.D. Green, Prof. J.K. Heyes, Dr. J.M. Hinch, Dr. J.A.G. Irwin, Prof. A. Kerr, Dr. G. Kirby, Dr. J.F. Longworth, Dr. P. MeGee, Dr. P. Merriman, Dr. M. Morris (South Africa), Dr. I. Muirhead, Dr. K. Old, Dr. D. Parbery, Mr. R. Pitkethley, Dr. T.V. Price, Dr. W.A. Shipton, Mr. J. Simpson, Dr. I.W. Smith, Dr. A. Stewart, Dr. J. Vermeulen (The Netherlands), Dr. T. Wardlaw and Dr. A. Wood.

References

Badow, B.A. (1981) – The Australian flora: its origin and evolution. Flora of Australia 1: 25–75.

Büchen-Osmond, C., Crabtree, K., Gibbs, A. and McLean, G. (1988) – Viruses of Plants in Australia. Descriptions and lists from the VIDE database. The Australian National University, Canberra.

Castles, I. (1991) – Year Book Australia 1991. Australian Bureau of Statistics, Canberra.

Farr, D.F., Bills, G.F., Chamuris, G.P. and Rossrnan, A.Y. (1 989) – Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, Minn., USA

Fish, S. (1 976) – Daniel McAlpine, a pioneer plant pathologist of Australia. Australian Plant Pathology Society Newsletter 5: 11–13.

Hartley, W. (1 979) – A Checklist of Economic Plants in Australia. Commonwealth Scientific and Industrial Research Organisation, Melbourne.

Hawksworth,D.L. (1991) – The fungal dimension of biodiversity: magnitude, significance and conservation. Mycological Research 96: 641–655.

Hnatiuk, R.J. (1990) – Census of Australian Vascular Plants. Australian Flora and Fauna Series No. 11. Australian Government Publishing Service, Canberra.

Khair, G.T. (1986) – List of Plant Parasitic Nematodes of Australia. 3rd Edition. Australian Government Publishing Service, Canberra.

Lord, E.E. (1973)– Shrubs and Trees for Australian Gardens. Lothian Publishing Co. Pty. Ltd., Melbourne.

Moffett, M.L. (1983) – Bacterial Plant Pathogens Recorded in Australia. In Plant Bacterial Diseases. A Diagnostic Guide (Eds P.C. Fahy and G.J. Persley), Chapter 15 Academic Press, Sydney.

Pascoe, I.G. and Sutton, B.C. (1987) – Research into fungal diseases of Australian native plants. Australian Horticulture Jan. 1987, pp. 40–43.

Walker, J. (1966) – Expanding the paths of Australian plant pathology. Proceedings of the Australian Plant Pathology Conference, Toowoomba, Queensland, 22 pp., issued separately.

Wortman, S. and Cummings, R.W. Jr. (1 978) ~ To Feed this World; the Challenge and the Strategy. The John Hopkins University Press, Baltimore.

Yates Garden Guide for Australian Gardeners (1988) – Collins, Australia.

Zimsky, M. (1991) – Using nitrogen-fixing tree products for human consumption. Tropical Resources Institute News 10: 6–9 (from Yale School of Forestry and Environmental Studies). 

Table 1 Some component disciplines of plant pathology in roughly chronological order of their development

 All develop in a social, political and economic context completely surrounded by the natural world.

Table2 Number of vascular plant species (native and introduced naturalised) in Australia (from Hnatiuk 1990)

Table 3 Estimates of number of species of introduced cultivated plants in Australia^A

^A Counts made from a variety of sources including Hartley (1979), Lord (1973) and Yates Garden Guide (1988).

^B Plus 2000 miscellaneous ornamentals.

Table 4 Land areas devoted to various uses in Australia (from Castles 1991)

^A The remainder of the area (excluding native and plantation forests) is taken up by urban development, mining leases, deserts and large tracts of land, some of which are under grazing leases but are not always grazed.

^B Forest is defined as having plants with an actual or potential height of 20 metres or more.

Table 5 Value of agricultural and livestock production in Australia (from Castles 1991)

Table 6 Estimates of number of ‘species’ of plant pathogens in Australia and their host genera and species

^A Figures estimated from sampled counts of published State plant disease cheek lists and Herb.DAR records.

^B Figures from counts of records given by Moffett (1983).

^C Figures from counts of records given by Büchen-Osmond et al. (1988).

^D Figures from counts of records given by Khair (1986).

^E Figures from Farr et al. (1989). The area covered includes continental USA, Alaska, Hawaii, Puerto Rico and the Virgin Islands.

^F Most of the host genera and species shown for bacteria, viruses and nematodes are also fungal hosts, so these figures are not cumulative.

^G For bacteria, each pathovar was counted and for viruses, the taxonomic groupings under which hosts were listed by Büchen-Osmond et al. (1988) were counted as ‘species’.

Table 7 Comparison of reports of plant fungi from Australia with those from the United States of America and with size of the flora

^A For sources of figures, see Tables 2 and 5.

^B Host and fungus figures from Farr et al. (1989). The area covered includes continental USA, Alaska, Hawaii, Puerto Rico and the Virgin Islands.

^C This figure is the total for the area covered by Farr et al. (1989); see Hawksworth (1991).

Table 8 Estimated losses of potential crop production due to various causes, by world regions (adapted from Wortman and Cummings 1978)

Table 9 Plant pathologists in Australia: distribution by employing body