DANIEL McALPINE MEMORIAL LECTURE 1980
Taxonomy, Specimens and Plant Diseases
Mr. Chairman, Ladies and Gentlemen. It is a great privilege to have been
invited to talk to you this morning in the third lecture dedicated to Daniel
McAlpine, and I thank you sincerely for giving me this opportunity. To be
associated with anything to do with McAlpine is to feel a sense of awe at the
number and diversity of his achievements, especially in the fields of plant
pathology and taxonomic mycology. To the present day, he is highly honoured in
both and, indeed, his many publications (over 200 papers, reports and books)
show that he didn't think of them as two separate areas but merely as two
aspects of his investigations on Australian plant diseases. Unfortunately, his
broad approach is no longer widely adopted and there has been a tendency over
the past fifty years to divorce taxonomic studies of plant pathogens from the
many other biological and ecological factors investigated. This morning, I wish
to put forward for your consideration some points to illustrate the relevance of
classificatory and taxonomic studies in work on plant diseases. I have dealt in
detail elsewhere with the relationship of taxonomy to plant pathology (Walker,
1975) but I don't think that some repetition is out of place now. Whilst I shall
be mainly using the fungi as examples, what I say is applicable (with varying
modifications) to all the groups of plant parasites, and to the non-parasitic
disorders of plants. First I will consider some basic aspects of classification,
identification and use of names, then discuss the importance of these procedures
in plant pathology and finally suggest actions which could be taken to improve
the situation in this part of the world.
To classify and arrange in an orderly fashion is one of our most basic
instincts. We tend to put together things we regard as related. Think of the
diversity of your own possessions and how you tend to have them sorted into
related groups such as books, clothes, crockery, cutlery and so on. This type of
sorting results in a classification and a filing system. The basic instinct to
sort things on the basis of relationships and to file them accordingly has the
practical result that things are easier to find when we want them. The two
elements of classification or taxonomy (on the one hand) and of greater ease of
finding or identification (on the other) can thus be seen to be intimately
related. Indeed, the ease of identification depends on the orderliness of the
classification and the ability of the searcher to find his way around in it. For
this reason, people who expect identifications and at the same time have the
attitude that taxonomy is bunkum have completely overlooked the obligate
relationship that exists between the two.
Practically everything we can think of is classified in some way or another, and
once groups have been formed, a terminology and nomenclature develops so that we
can talk about these groups or taxa as they are usually called in
biology.
Words are classified in a dictionary in alphabetical order, for ease of finding
and so that their meaning can be discovered.
Of course, they may be classified in other ways. In a thesaurus, they are
arranged according to meaning, so that a variety of words with a similar meaning
can be readily found.
In music, we see not only a classification but a language that has developed to
express it. If one wants to study music, one must learn both the classification
and the language that expresses it. The discipline thus imposes its own rules on
the disciple. For this reason, plant pathologists should not quaver when faced
with taxonomic papers or become crotchety about technical taxonomic terms and
scientific names; most fields have them in one form or another. The only
sensible thing to do when technical difficulties arise is to seek the help of an
expert in the field.
For the non-professional musician, a key for the identification of tunes has
been developed (Parsons, 1975). All that the enquirer needs to know is the first
15 notes, and whether they go up, down or repeat the one before. In this way,
many thousands of tunes can be identified. This is an example of how, from a
highly technical subject, it is sometimes possible to devise in simple terms an
identification system (or musical key in this case) for general use. Not
everyone needs to be a professional musician to appreciate and benefit from
music; not everyone needs to be a professional taxonomist to appreciate and
benefit from taxonomy.
Other classifications are in constant use to help provide rapid and accurate
identifications. Whether it is criminals breaking in and entering or new
diseases entering and breaking out, rapid and accurate identification is an
essential first step in tracking them down and trying to restrain their
destructive tendencies. An organised fingerprint collection is a major tool in
such detective work. Moreover, when gross morphology may lead to a
misidentification (the three pathologists shown are not the same), study of the
fine details is necessary to separate them (the slide illustrated three men with
similar facial characteristics but quite distinct fingerprint patterns).
Use of the fingerprint as a distinguishing character (or indeed set of
characters) has been possible only after extensive analysis of a wide range of
prints and the development of a taxonomic system to classify prints, and a
nomenclature to refer to them. Not all policemen need to be fingerprint experts,
but all see the need to make use of their expertise as part of the whole
investigation.
Some of the fingerprints used in plant pathology are not so very different as
appearance from those just shown. The perineal patterns of species of
Meloidogyne or the sculpturing on fungal spores provide characters of value in
classification and identification.
Implicit in all that I have said so far is the fact that, whether it be tracking
down a tune, a criminal or a plant disease, we usually begin with a specimen. It
may only be a fragment of a melody that we cannot get out of our head, or a
fingerprint on the whisky glass, or a leaf spot, or a collection of rotting
roots, or any one of a wide variety of things. Whatever it is, it is the
starting point for all the work that follows. Not only is it the starting point,
it is the evidence for what has happened and, once it is accurately identified
as a fingerprint of a known criminal or as a uredinium of Puccinia striiformis,
it provides a permanent reference with which later unidentified specimens can be
compared. The more comprehensive the collection of fingerprints or specimens,
the more likely the accurate and rapid identification of any later unknown
collection. Moreover, these reference collections must be available locally
where the identifications are required, with expert staff to man them. In
addition, if fingerprints of criminals and specimens of pathogens from other
countries are also filed in the local collections, then these illegal immigrants
can be identified much more rapidly should they attempt to enter the country.
In summary, it can be seen that
(i) identifications flow from classifications
(i i) the material basis of classification and identification is specimens; as '
Dr. E. W. Mason (1940) said forty years ago, 'identification means the matching
of good specimens of the species to be named against good specimens that have
already been correctly named'.
(ii) identified specimens, filed in collections, provide the basis for our
knowledge of what occurs where, the material for research to find more
informative classifications and reference material to help in identifying
unknowns.
Taxonomy and the classifications developed are a matter of personal opinion.
Different people will sort the same set of things into different groups.
However, once we come to name the groups, stability is required so that we
always use the same name for the same group and not for different groups. For
this reason, in biology the use of names is governed strictly by the
International Codes of Nomenclature. There are botanical, zoological and
bacteriological codes, and a code for cultivated plants. Fungi are governed by
the botanical code at present. Briefly, the code requires that every name be
attached to a specimen, called the nomenclatural type (or type specimen),
nominated by the original describer. It is this specimen which governs the use
of the name. To use a name for any other specimen implies that, in the
characteristics that are important in distinguishing one group from another,
this specimen is the same as the type specimen. Type specimens are thus
international standards to which reference can be made to ensure that names are
being used in the correct sense intended by the person who originally named the
organism. They are thus analogous to those other international standards which
ensure the uniformity of use of units of measurements of various physical
factors such as length, weight, and the wavelength of light. The specimen shown
is the type specimen of Uromyces trifolii (Hedw. f. ex DC.) Fcki which occurs on
white clover (Trifolium repens L). This specimen is filed in the herbarium at
Geneva. The exact identity of this rust had been confused in much of the earlier
work on clover rusts but examination of the type has shown that the name
properly applies to the microcyclic rust of white clover, known only in the
telial stage and forming large telia on leaflets and petioles, which are often
twisted and distorted. To use the name U. tritolii for any of the other rusts of
Trifolium is incorrect, as such usage is not in accord with the characters shown
by the nomenclatural type. Two other specimens (from Saccardo's herbarium) are
shown.
Having thus considered some of the basic features of classifications, specimens
and the use of names, I would now like to consider directly the relevance of
taxonomy in plant pathology. To do this, I have chosen three or four areas of
work with which I will deal in some detail. Any other areas would have done as
well to illustrate the significance of taxonomy; my reason for choosing these is
that they raise certain other matters I wished to mention. The areas to be
discussed are scientific names and publications, perfect and imperfect states,
diseases of native plants, diseases of weeds and quarantine.
SCIENTIFIC NAMES AND PUBLICATIONS
I have said already that the use of names of organisms is governed strictly by
International Rules. This is necessary if stability of nomenclature is to be
achieved and if the use of the same name in several different senses is to be
avoided. Unfortunately, due to a variety of factors, the literature contains
many examples of names used in different senses. Plant pathologists are both
producers and consumers of the literature and have thus contributed to and been
confused by the literature and have thus contributed to and been confused by
this situation. I mentioned earlier the case of the white clover rust, Uromyces
trifolii. In the earlier literature, this name refers to at least three rusts,
now known to be quite distinct, and it is only by careful investigation that the
different rusts being referred to by various workers under the same name U.
trifolii can be determined. Taxonomic work has established the correct sense in
which this name should be used, but the various usages in the older literature
(and in some current publications) are a factor that pathologists need to
consider when doing literature searches. Another example is the name
Colletotrichum gloeosporioides which is widely used in plant pathological
literature for fungi found associated with a wide range of diseases on a wide
range of hosts. Originally, this species was described as Vermicularia
gloeosporioides by Penzig (1882) in Italy, from a specimen of leaves of a
species of Citrus. Later Saccardo (1884) transferred it to the genus
Colletotrichum and the full name Colletotrichum gloesporioides (Penz.) Sacc.
reflects this history. However, thousands of later workers have used this name
for broadly similar fungi on many plants other than Citrus and a recent
monograph of the genus Colletotrichum (Arx, 1957) listed over 600 names of fungi
which that author regards as not significantly different from C. gloeosporioides.
However, several more recent studies indicate that this wide use of the name C.
gloeosporioides probably embraces several fungi which are distinct from that
described on Citrus by Penzig and which should be considered as distinct
species. People searching the literature on C. gloeosporioides should be aware
of this and realise that references containing this name are not necessarily
talking about the same fungus at all. Moreover, many references of value could
be found under several of the other names listed as synonyms. Many other cases
of this sort exist, and they can lead to considerable misunderstanding and
confusion. Advice from taxonomists regarding synonyms and possible literature
confusion in the use of names could save much time and trouble.
PERFECT AND IMPERFECT STATES
Many fungi are polymorphic and can exist in several forms, often as a perfect
state (in the Ascomycotina or Basidiomycotina) and one or more imperfect states.
Knowledge of the correlations of perfect and imperfect states is of considerable
importance in epidemiological and disease control work. Several hundred such
correlations have been proposed in the literature but proofs put forward for
them have varying degrees of validity and certainty. The most complete list of
these correlations available together with comments on the degree of reliability
of the evidence for them has been compiled by Kendrick & DiCosmo, contains
over 1200 entries and is published in the two volume work 'The Whole Fungus'
(Kendrick, 1979). As with the literature, taxonomic advice can often be valuable
here to assess the evidence for suspected perfect - imperfect state
correlations.
NATIVE PLANTS
Five main aspects will be considered. These are: the effect of diseases on the
native flora, the effect of diseases on native plants growing under cultivated
conditions, the effect of native pathogens on introduced cultivated
plants, the danger of the native flora from introduced diseases, and provision
of information on native plant diseases to other countries.
(i) the effect of diseases on the native flora As far as damage to the native flora is co@cerned, many native diseases of native plants appear to be in some balance with the flora. Foresters especially are becoming more aware of the need to study diseases of native tree species and to estimate the damage being caused and recent work on Armillaria in Australia has shown the relevance of taxonomy in this field (Podger et al., 1978). Many pathogens of the native flora are undescribed and considerable descriptive work must accompany disease investigations. The series of papers published by Dr. Harry Swart in the Transactions of the British Mycological Society on fungal parasites of native plants are descriptive models for all working in this field.
(ii) the effect of diseases on native plants growing under cultivated
conditions
Here much increased damage is often observed. Various species of Mycosphaerella
occurring at a low level in the bush can cause severe damage to various species
of Eucalyptus under cultivated conditions. This can be seen in Australian
gardens and nurseries and also in New Zealand on introduced eucalypts. The
identity, host range and life cycles of these species of Mycosphaerelia requires
detailed investigation. Moreover, in cultivation, native plants are sometimes
affected by diseases not recorded on them in natue. In New South Wales
nurseries, seedling eucalyptus are often severely damaged and killed by a
conidial powdery mildew (species not known) whereas, as far as I know, powdery
mildew has never been recorded on naturally grown eucalypts.
(iii) the effect of native pathogens on introduced cultivated plants
Several native pathogens have spread to and damaged introduced cultivated
species. Soybean rust, Phakospora pachyrhizi Syd., is native in eastern
Australia on several leguminous genera and is able to attack soybean and some
other introduced plants. Other examples such as Puccinia lagenophorae Cke on
Compositae, and Armillaria luteobubalina Watling & Kile, in Podger et al. on
native and introduced species hosts could be quoted. In some cases lack of
knowledge of the native diseases causes problems in decisions about crop
diseases. In New South Wales and Queensland, both a downy mildew (Peronospora
sp.) and a leaf and stem gall (Synchytrium sp., similar to S. dolichi (Cke)
Gaeumann), occur on native species of Glycine. With an outbreak a few years ago
of a downy mildew of soybean in quarantine plots on the north coast of New South
Wales, it could not be determined accurately, whether the disease was a new
introduction or whether it had come from the native Glycine spp.. It was treated
as a new introduction but obviously a deal of work is required to find out
whether it had come from the native disease is a source of infection for the
crop plants. Several similar situations exist, such as our lack of knowledge of
the downy mildews present on native grasses in relation to the recent recording
of maize downy mildew ( Sclerospora maydis (Racib.) Butler) in the Northern
Territory and the north of Western Australia.
(iv) the danger of introduced diseases to the native flora As mentioned earlier,
the native flora seems to be in good balance with its native diseases. When
disturbance occurs, and pathogens are encouraged or are introduced into new
areas, damage to susceptible species can be severe and can have widespread
ecological, economic and social repercussions, as Phytophthora cinnamomi has
shown in several states. Overseas, there are diseases which could cause severe
damage to the native flora if they were introduced. The rust, Puccinia psidii
Wint., which occurs on guavas in Central America, can cause leaf damage to some
Australian Eucalyptus spp.. The fungus Diaporthe cubensis Bruner can also cause
severe trunk cankering and death of some species of Eucalyptus, such as E.
grandis Maiden, E. saligna Sm. and others in Brazil, Florida, Hawaii and Puerto
Rico (Hodges et al. 1979). Severe infection appears to be associated with
planting eucalypts in areas where temperatures and rainfall are high during most
of the year. These and other diseases are undesirable imports and could cause
severe ecological damage in some parts of Australia if introduced.
(v) provision of information on native plant diseases to other countries
Australian native plants are now growing in many other countries, either as
useful crop or ornamental species, or in some cases as troublesome weeds. Just
as we look to other countries for information on diseases of plants that we have
introduced, so other countries look to us for similar information about our
plants. The mycorrhizal relationships of plants in their native habitat are also
of considerable practical interest. A recent enquiry concerned certain diseases
of Hakea and Acacia occurring in Australia which could have potential for study
as biological control agents for Australian species introduced to South Africa
which have become troublesome weeds there. Taxonomic aspects enter into all such
considerations of the very neglected field of native plant diseases.
WEED DISEASES
Weeds may act as alternative hosts for many crop diseases and many examples
could be quoted. It is necessary to determine if pathogens on weeds are the same
as those on botanically related crop plants, both at the species level and
below. Physiologic specialisation probably occurs in many pathogens and
extensive investigations at this level are needed to determine whether races
exist and if so what their host ranges are.
Weed pathogens have also come into prominence in recent years as potential
biological control agents for weeds. The introduction and spread of skeleton
weed rust, Puccinia chondrillina Bub., has been well documented and published
papers report a significant decline in the population of the susceptible race of
skeleton weed due to rust attack. Several organisations are considering the
possibility of introducing other pathogens not recorded in Australia to help in
the control of such weeds as blackberry (Rubus spp.), lantana (Lantana camara
L.) onion weed (Asphodelus fistulosus L.) and rubber vine (Cryptostegia
grandiflora R. Br.). These pathogens occur on the weed species in its country of
origin and elsewhere and varying amounts of damage are reported. The
organisations do not claim that introduced pathogens would completely control
the weeds in question, but that they would be an added adverse factor for the
weeds, helping reduce their vitality and thus considerably aiding weed
management.
In proposals of this sort, taxonomic considerations of hosts and pathogens are
of vital importance. Some weed occur in the same families, sometimes in the same
genera, as crop or native species. Introduction of a pathogen new to Australia
may cause damage to the weed but also could possibly result in a new disease of
a crop or native species, with the added cost of control measures for the crop
and the danger of disease and ecological upset in the native flora. Of course,
extensive inoculation tests are carried out on crop and native species with the
candidate pathogen and care is taken to try and enquires that any race
introduced would be specific to the candidate weed species. However, with some
fungi, and especially the rusts, the possibility of introducing the genetic
potential for several races even in a single spore culture is present. The
possibility that some extension of host range beyond that recorded in
inoculation tests or in nature in the country of origin of the rust must always
be kept in mind. This is exemplified by the rust of noogoora burr (Xanthium
pungens Walir.), Puccinia xanthii Schw., which was first recorded in Australia
near Brisbane, Queensland early in 1975. P. xanthii is native to North America,
where it was described in 1822, and occurs only on various species of Xanthium
and Ambrosia. It has also been recorded from the West Indies, Hawaii, Japan and
Europe on these two genera. Since its first record in Australia in 1975 on
noogoora burr, it has also been recorded in the field and in artificial
inoculation tests on some lines of sunflower (Helianthus annuus L.) and on
English marigold (Calendula officinalis L.) (Alcorn, 1976). P. xanthii is a
microcyclic rust and there is no previous record of any microcyclic rust
anywhere in the world on Helianthus. A related but different microcyclic species
has been recorded on Calendula in the United States. Moreover, inoculation tests
carried out in 1974 (Hasan, 1974) with an isoiate from Italy reported as
virulent on Australian forms of noogoora and bathurst (Xanthium spinosum L.)
burrs also stated that 'It has been demonstrated that the rust does not infect
plants of the closely related genera Helianthus, Dahlia and Zinnia'. It seems
that the Australian records, certainly on Helianthus and probably on Calendula
represent the first records of P. xanthii on two host genera not previously
recorded. It is only fair at this stage to say that this view has been
questioned by some people in Australia, especially regarding the taxonomy of P.
xanthii and related rusts on other hosts. However, evidence that is now
accumulating (and which will be reported at a later date) lends support to the
conclusion that an extension of host range has been observed.
I should also point out in this context that experience over the past thirty
years shows that several diseases, especially rusts, that become established in
eastern Australia are found within a year or two in New Zealand. This
transTasman spread in an easterly direction, presumably as airborne spores, has
been documented for several rusts. For this reason, the flora of New Zealand
(crops, trees and native plants) and the diseases not recorded there must be
seriously considered when proposals for introducing pathogens for biological
control purposes are being considered.
QUARANTINE
In considering diseases on weeds and native plants, some quarantine situations
have been mentioned. Accuracy of information about the identity of organisms is
essential if rational and effective decisions about quarantine are to be made.
We need to know accurately what we have in Australia so as to know what we don't
have. When legislation is framed, accuracy in identification of the organisms
concerned and the use of the names referring to them is essential. Trade between
Australia and other countries often requires us to give declarations of the
absence of particular organisms from the whole or part of Australia; in reverse,
interceptions of diseases in imported consignments require rapid and accurate
identification, not only from the disease point of view but because of economic
and other disadvantages that delays in identification can cause exporters and
importers. With outbreaks of disease, accurate and rapid identification is again
one of the main factors helping to decide what action to take. Quarantine also
needs to be considered for subspecific taxa to prevent the introduction of new
races or mating types which could alter the virulence and behaviour
of species already present.
I could discuss other areas of work such as mycorrhizal fungi, the development
of fungicide resistance, preparation of check lists of plant diseases, spray
guides and growers bulletins etc. but I hope that what I have said already has
given you a small glimpse of how taxonomic investigations are important in plant
pathology and, indeed, are essential in many of the day-to-day problems and
decisions that we all need to make. Having outlined how taxonomy can help you, I
now want to say how you can help taxonomy and, indeed, how you must help it if
it is to help you.
Specimens are basic to the whole business. What do I mean by a specimen in the
context of plant pathology? It is the diseased plant, the cultures, nematodes,
microscope slides etc. that derive from it, and the information concerning
identities of host and pathogens, the disease caused, and date, locality and
collectors name. Even in the case of bacterial and virus diseases and of
non-parasitic conditions, the specimen, if properly collected, will provide an
accurate record of the identity of the host plant (which can be examined
botanically if doubts arise). Moreover, characteristic symptoms are often shown
in such cases.
Many early collections of Australian fungi are filed in overseas herbaria, with
a major collection in the Herbarium of the Royal Botanic Gardens, Kew. As far as
local collections are concerned, you will find amongst your conference papers an
attempt to list the mycological herbaria and culture collections in Australasia
(Walker, 1980). The total number of specimens that I could find was about
330,000 over one third of which are lichens. The 330,000 specimens are spread
over 79 institutions but the bulk of the fungi (excluding the lichens) are held
by seven. When we consider that a total of over 3.3 million plant specimens are
held in the five botanical herbaria in Adelaide, Auckland, Brisband, Melbourne
and Sydney alone (let alone the many other large botanical collections in
Australia and New Zealand), the paucity of local collections of fungi becomes
apparent.
Unfortunately many plant disease specimens on which published work is based have
not been kept and it is thus impossible to resolve questions that arise about
the identity of the organisms referred to in some of these paper. Although many
plant pathologists now regularly send specimens to local herbaria for
identification and filing, the discarding of specimens by some workers is still
a problem. It prevents important aspects of their work from being checked,
destroys the evidence for the occurrence of the organisms at that particular
time and place on the host or substrate concerned, and severely hampers
taxonomic research.
There is also a severe shortage of people specialising in taxonomy of fungi and
other micro-organisms in Australia. As far as the fungi are concerned, the
number of people who spend a large proportion of their time working in taxonomy
is seven or eight. In recent years, retirement and death have removed some
highly competent mycologists and they have not been replaced. For these reasons,
I wish to suggest the following positive steps which, with your support
individually as plant pathologists and administrators and collectively as the
Australian Plant Pathology Society, can help the development of taxonomic work
in this part of the world:
1. Development of National Collections of Microorganisms
The possibility of developing national collections for
fungi, bacteria, viruses and nematodes is being discussed. For the fungi and for
plant disease specimens in general, the three herbaria in the Plant Pathology
Branches at Burniey, lndooroopilly and Rydalmere have been nominated as the
basis of the national collection. Between them, these three collections hold the
bulk of specimens of plant parasitic fungi in Australia. If additional staff
were provided for taxonomic and curatorial work and uniform computer indexing
facilities introduced, a very valuable source of information for Australian
plant pathology would be made much more accessible. Similar arrangements are
needed for the other groups of organisms. Due to our geographical position, I
also see no reason why these collections should not co-operate with plant
pathologists throughout South-East Asia and the Pacific and eventually develop
as reference collections for this part of the world. I understand that the
D.S.I.R. Plant Diseases Division Herbarium in Auckland now has some commitment
to plant disease survey and identification work in an area of the South Pacific.
2. Training and employment of taxonomic staff At present, there are no jobs
available in taxonomic
mycology in Australia (as far as I know) and I suspect that the situation is
similar for taxonomic mycology in Australia (as far as I know) and I suspect
that the situation is similar for taxonomic work on other groups of
micro-organisms. If National Collections are to be developed, many more people
working in taxonomy will be needed soon. At present, the three herbaria at
Burnley, lndooroopilly and Rydalmere are all one-taxonomist shows. It's no use
kidding ourselves that we can have effective collections unless we provide the
people to staff them and long-term continuity. Government and employers must be
informed by the plant pathologists they employ of the importance and relevance
of taxonomic work and of the immediate need for more positions for taxonomists
to work in close association with active groups of plant pathologists. Moreover,
the relevance of taxonomy to plant pathology needs to be stressed in university
plant pathology courses and taxonomy should be presented as a real option for
later specialisation. After graduation, it takes several years working with
fungi for a person to become competent in taxonomy and a similar period is
probably required with other organisms. We thus need to get suitable people, who
are interested in taxonomy, into these jobs as soon as we can.
3. Keeping of specimens and cultures
Once the national collections are a reality, a proper
system for the identification and permanent filing of all Australian specimens
should be possible. However, even now there are places in Australia to which
specimens can be sent and your list of herbaria and culture collections should
provide this information. As far as plant parasitic and other fungi are
concerned, the branches of the National Fungus Collection at Burnley,
Indooroopilly and Rydalmere are probably the most suitable collections. Where it
is desired to send collections overseas for identification, this is best done
through a local collection so that a duplicate can be retained locally for later
reference. Otherwise, the whole collection is kept overseas and is relatively
inaccessible for reference in its country of origin.
In order to improve the retention of specimens, I suggest the following:
(a) for all degrees, it be made a condition for the granting of the degree that
specimens and cultures used in work for the degree be lodged in one of the major
local collections.
(b) that editorial committees and editors of biological journals require before
publication that papers etc. in which organisms are dealt with should show
evidence that the specimens and cultures have been lodged in a major local
collection. The best evidence is the listing of the specimens together with the
accession numbers allocated to them by the herbarium or culture collection where
they are filed. I may say that it is not only taxonomic papers to which I am
referring here but to all papers which have been based on examination of, or
work done with, specimens or cultures. Disease surveys and similar studies
should also refer to specimens authenticating the records listed. In this
regard, it is necessary to distinguish between a record, which is based on an
authenticating specimen and a report, which is not backed up by a specimen in a
collection.
4. Forest pathology
In recent years, diseases of trees, both native and introduced, have received
much greater attention and forest pathology in Australia has developed rapidly.
It has tended to develop separately from agricultural plant pathology and I
think that the time has now arrived where much greater contact and co-operation
is needed between the two groups. We all deal with plant diseases and have much
in common. In quarantine especially we have common interests and, indeed, some
of the tree rusts in other countries have as alternate hosts a wide range of
annual and perennial plants in several families such as the Pteridophyta,
Ericaceae, Rosaceae, Salicaceae and others and including cultivated plants such
as apples and pears. Close association of agricultural and forest pathology in
working groups and on committees would be of mutual benefit.
Taxonomy is not just morphology, but the summary of all that we know about
organisms incorporated into an orderly system. In 1895, McAlpine summarised our
need for the best possible taxonomic work in plant disease investigations in
these words: 'in dealing with the diseases of plants due to Fungi, it is
necessary to determine the name and nature of the Fungus causing the disease, in
order to be able to cope with it and to take effectual measures for its
prevention, palliation or cure', and "It must not be imagined that because
we have tabulated and briefly described a number of Fungi we therefore know all
that is necessary about them. The most fascinating branch is the life history -
the story of their lives from year to year; and it is this knowledge as to their
various and often disguised phases, how they spread and where they winter, which
will help us to cope with them successfully'.
During this conference, names of organisms will be used many thousands of times.
I would ask you to reflect as you use these names on what they are based and
their correct and accurate usage and you will find underlying all of them, in
the final analysis, specimens and taxonomic considerations.
In our lives as plant pathologists, we do not work just for now and for
ourselves, but for all who come after as well. If we do not retain the material
evidence for our work, we deny them the opportunity and the right to check the
basis of our findings in the light of their knowledge. I feel sure that none of
us wish to do such a disservice to plant pathology and I commend to you all the
diligence and care shown by the first Australian plant pathologist to whom this
lecture is dedicated.
REFERENCES