Diseases and Pathogens of Eucalypts

Over the last fifty years, there has been an increasing recognition that eucalypts are vulnerable to a wide range of diseases. They have suffered destructive epidemics, particularly of dieback caused by the cinnamon fungus in native forests, of foliar diseases and cankers in plantations, and of dieback of remnant trees on agricultural and grazing land.

This has stimulated intensive research into the causes and management of diseases of the eucalypts. This work represents a comprehensive review of our current knowledge of the health and diseases of eucalypts.

• Language: English
• Publisher: CSIRO PUBLISHING
• Release date: Oct 25, 2000
• ISBN: 9780643098848

Book preview

Diseases and Pathogens of

EUCALYPTS

Dedication

This book is dedicated to the memory of Dr Geoffrey Charles Marks (1932–90) who, after 27 years of experience as a Forest Pathologist with the Victorian Government and as a teacher of Forest Pathology at the University of Melbourne, saw the need for such a book. He initiated its writing and undertook the initial planning of its structure and authorship.

Geoff was born in Sri Lanka (formerly Ceylon) and was an outstanding athlete and scholar, representing his country as a swimmer at the Helsinki Olympics and completing an honours degree in science at the University of Ceylon, followed by an MSc (1961) and PhD (1963) while on a Rockefeller Foundation Scholarship at the University of Wisconsin. He took up his appointment with the then Forests Commission of Victoria in Melbourne in 1963 and thereafter was involved in the study of eucalypt diseases, being a central participant in the initial studies of dieback caused by Phytophthora cinnamomi in Victorian eucalypt forests. He also initiated early studies on the eucalypt leaf pathogen, Mycosphaerella, in southern Australia.

His keen intellect, enlightened attitudes, great enthusiasm and curiosity, waspish good humour and propensity to provoke critical discussion inspired colleagues and led to fruitful collaborations with many people.

He developed a deep appreciation of the eucalypt forests of his adopted country, and from this grew his keen understanding of their ecology and pathology. He conducted wide ranging field studies on many aspects of forest pathology and greatly enjoyed field trips to investigate disease problems in the diverse forests of Victoria, tirelessly speculating about the complex causes of the diseases and planning experimental studies with whomever was fortunate enough to accompany him. While returning home from one of these long trips to the forests of eastern Victoria he was seriously injured in a car accident. He showed great courage in recovery, and never lost his enthusiasm, expressed at the time by his delight in initiating and planning this book. He was not destined to see this work to fruition as he died suddenly in August 1990. Vale, Geoff.

We hope this book has not fallen too far short of your vision.

Diseases and Pathogens of

EUCALYPTS

P. J. Keane, G. A. Kile, F. D. Podger and B. N. Brown (Editors)

© CSIRO 2000

All rights reserved. Except under the conditions described in the Australian Copyright Act 1968 and subsequent amendments, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the prior permission of the copyright owner. Contact CSIRO PUBLISHING for all permission requests.

National Library of Australia Cataloguing-in-Publication entry

Diseases and pathogens of eucalypts.

Bibliography.

Includes index.

ISBN 0 643 06523 7 (paperback).

ISBN 0 643 09012 6 (eBook).

1. Eucalyptus – Diseases and pests – Australia.

I. Keane, Philip J.

634.9737660994

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Cover photographs

Upper: Crown decline typical of that observed in trees of Eucalyptus obliqua and E. regnans affected by regrowth dieback and Armillaria.

Lower: Crinkle leaf caused by Mycosphaerella cryptica on tip leaves of a seedling of Eucalyptus obliqua.

Publication of this book was supported by a grant from the Standing Committee on Forestry of the Australian Ministerial Council on Forestry, Fisheries and Aquaculture.

CONTENTS  

Preface

Contributors

Section I: The Eucalypts—Their Importance, Diversity and Biology

1   Economic and Social Importance of Eucalypts

J.W. Turnbull

Summary

1.1   Introduction

1.2   Eucalypts in native forests

1.3   Eucalypts as exotics

1.4   Industrial eucalypt plantations

1.5   Eucalypts in the rural landscape

1.6   Conclusion

1.7   References

2   Morphology, Phylogeny, Origin, Distribution and Genetic Diversity of the Eucalypts

B.M. Potts and L.A. Pederick

Summary

2.1   Introduction

2.2   Morphology

2.3   Phylogeny

2.4   Origins

2.5   Distribution

2.6   Hybridisation

2.7   Genetic variation

2.8   Genetic variation in susceptibility to disease

2.9   Factors affecting disease risk in plantations

2.10   Acknowledgments

2.11   References

3   Growth Habits and Silviculture of Eucalypts

R.G. Florence

Summary

3.1   Introduction

3.2   Growth habits of the eucalypts

3.3   Sivicultural practice in natural forests

3.4   Ecologically sustainable silviculture

3.5   New directions in silviculture

3.6   Eucalypt plantations

3.7   Conclusion

3.8   References

4   Ecology of Eucalypt Regeneration

D.H. Ashton

Summary

4.1   Introduction

4.2   Characteristics of eucalypts in relation to their regeneration

4.3   Conditions required for regeneration

4.4   Major modes of regeneration

4.5   In synthesis—the strategies of survival

4.6   References

5   Physiology of Eucalypts in Relation to Disease

C.L. Beadle

Summary

5.1   Introduction

5.2   Productivity and light interception

5.3   Biomass production, partitioning of dry mass and foliage

5.4   Gas exchange and stomatal conductance

5.5   Water relations

5.6   Conclusion

5.7   References

6   Mycorrhizas of Eucalypts

G.A. Chilvers

Summary

6.1   Introduction

6.2   Structure of eucalypt mycorrhizas

6.3   Functioning of mycorrhizas

6.4   The fungal partners of eucalypts

6.5   Mycorrhizal infection cycles

6.6   Ecology of mycorrhizas

6.7   Manipulating eucalypt mycorrhizas

6.8   References

Section II: The Diseases of Eucalypts—Their Causes and Biology

7   Diseases and Fungi of the Reproductive Structures of Eucalypts

B.N. Brown

Summary

7.1   Introduction

7.2   Fungi of flowers and capsules and their pathogenicity

7.3   Seed fungi of eucalypts

7.4   Control of seed fungi

7.5   Conclusion

7.6   References

8   Disease during Propagation of Eucalypts

B.N. Brown and F.A. Ferreira

Summary

8.1   Introduction

8.2   Diseases with abiotic causes

8.3   Fungal diseases

8.4   Principal diseases of eucalypt cuttings

8.5   Conclusion

8.6   References

9   Fungal Diseases of Eucalypt Foliage

R.F. Park, P.J. Keane, M.J. Wingfield and P.W. Crous

Summary

9.1   Introduction

9.2   Target spot (Aulographina eucalypti)

9.3   Leaf spot, leaf blotch and crinkle leaf blight (Mycosphaerella species)

9.4   Biotrophic infections

9.5   Powdery mildews (Oidium species)

9.6   Eucalypt rust (Puccinia psidii)

9.7   Angular, vein-limited leaf spots

9.8   White leaf and shoot blight (Sporothrix pitereka )

9.9   Winter leaf spot (Piggotia substellata and Ceuthospora innumera)

9.10   Leaf spots and speckles of minor importance

9.11   Leaf spots and blights of stressed plants

9.12   Conclusion

9.13   Acknowledgments

9.14   References

10   Canker Diseases of Eucalypts

K.M. Old and E.M. Davison

Summary

10.1   Introduction242

10.2   Fungal invasion and host responses

10.3   Effect of plant stress on the development of cankers

10.4   Major canker diseases of eucalypts

10.5   Opportunistic pathogens associated with cankers in eucalypts

10.6   Conclusion

10.7   Acknowledgments

10.8   References

11   Diseases of Eucalypts Caused by Soilborne Species of Phytophthora and Pythium

B.L. Shearer and I.W. Smith

Summary

11.1   Introduction260

11.2   Origin of the pathogens

11.3   Host range

11.4   Distribution patterns and effect of disease

11.5   Host–pathogen interactions

11.6   Pathogenicity of Pythiaceae on eucalypts

11.7   Effects of disease on wood production and conservation values

11.8   Pathogen dynamics

11.9   Resistance mechanisms

11.10   Effects of environment on disease development in established infections

11.11   Conclusion

11.12   Acknowledgment

11.13   References

12   Woody Root Rots of Eucalypts

G.A. Kile

Summary

12.1   Introduction

12.2   Armillaria root disease

12.3   Pseudophaeolus root disease

12.4   Ganoderma root rot

12.5   Other woody root diseases

12.6   Conclusion

12.7   References

13   Stem and Butt Rot of Eucalypts

G.A. Kile and G.C. Johnson

Summary

13.1   Introduction

13.2   Causal organisms and hosts

13.3   The decay process

13.4   Factors affecting decay development

13.5   Particular heart rots and stem conditions

13.6   Conclusion

13.7   Acknowledgments

13.8   References

14   Diseases of Eucalypts Associated with Viruses, Phytoplasmas, Bacteria and Nematodes

T.J. Wardlaw, G.A. Kile and J.C. Dianese

Summary

14.1   Introduction

14.2   Virus-like diseases

14.3   Diseases associated with phytoplasmas

14.4   Diseases caused by bacteria

14.5   Diseases associated with nematodes

14.6   Conclusion

14.7   References

15   Mistletoes and other Phanerogams Parasitic on Eucalypts

N. Reid and Z. Yan

Summary

15.1   Introduction

15.2   Mistletoes parasitic on eucalypts

15.3   Native cherries parasitic on eucalypts

15.4   Dodder-laurels parasitic on eucalypts

15.5   Acknowledgments

15.6   References

16   Nutritional Disorders and other Abiotic Stresses of Eucalypts

P. Snowdon

Summary

16.1   Introduction

16.2   Diagnosis

16.3   Nutrient deficiencies

16.4   Toxicities

16.5   Water as an abiotic factor

16.6   Frost

16.7   Artificial environments

16.8   Miscellaneous abnormalities

16.9   Conclusion

16.10   References

17   Eucalypt Diseases of Complex Etiology

K.M. Old

Summary

17.1   Introduction

17.2   Etiology of diebacks and declines

17.3   Diebacks of native forests and woodlands

17.4   Forest diebacks associated with drought

17.5   Forest diebacks associated with successional changes

17.6   Forest and woodland diebacks associated with chronic insect herbivory

17.7   Plantation diseases of complex etiology

17.8   Conclusion

17.9   References

Colour Plates

Section III: Management of Eucalypt Diseases

18   Management of Eucalypt Diseases—Options and Constraints

J.A. Simpson and F.D. Podger

Summary

18.1   Introduction

18.2   Environmental concerns

18.3   Quarantine and eradication

18.4   Forest health surveillance

18.5   Approaches to disease management

18.6   Political and legislative considerations

18.7   Conclusion

18.8   Acknowledgments

18.9   References

19   Management of Disease in Native Eucalypt Forests and Woodlands

F.D. Podger and P.J. Keane

Summary

19.1   Introduction

19.2   Management of dieback caused by Phytophthora cinnamomi

19.3   Management of dieback diseases of complex etiology

19.4   Management of root rot caused by Armillaria luteobubalina

19.5   Management of foliar and canker diseases

19.6   Management of stem and butt rots

19.7   Conclusion

19.8   Acknowledgments

19.8   References

20   Management of Phytophthora cinnamomi during Bauxite Mining in Eucalyptus marginata Forest—A Special Case

I.J. Colquhoun and P.E. Elliott

Summary

20.1   Introduction

20.2   The mining operation

20.3   Objectives of rehabilitation and the dieback management program

20.4   The management strategy

20.5   Procedures for disease control

20.6   Success in management of disease

20.7   Conclusion

20.8   References

21   Management of Disease during Eucalypt Propagation

B.N. Brown

Summary

21.1   Management of nursery diseases—general principles

21.2   Two minimal-disease nursery systems

21.3   Control of particular nursery diseases

21.4   Control of principal diseases of eucalypt cutting programs

21.5   Conclusion

21.6   Acknowledgments

21.7   References

22   Management of Disease in Eucalypt Plantations

P.D. Gadgil, T.J. Wardlaw, F.A. Ferreira, J.K. Sharma, M.A. Dick, M.J. Wingfield and P.W. Crous

Summary

22.1   Introduction

22.2   Disease and the selection of species

22.3   Disease management strategies

22.4   Conclusion

22.5   Acknowledgments

22.6   References

Animal Index

Birds and Mammals Scientific Names

Birds and Mammals Common Names

Insects

Nematodes

Fungi and other Microorganisms (Actinomycetes, Bacteria, Oomycota, Phytoplasmas) Index

Plant Index

Eucalypt (Angophora, Corymbia, Eucalyptus) Scientific Names

Eucalypt (Angophora, Corymbia, Eucalyptus) Common Names

Other Plants

Subject Index

PREFACE  

The eucalypts (genera Eucalyptus, Corymbia and Angophora) are a unique group of mainly tree species. Despite more than two centuries of scientific study, their taxonomic circumscription is still incomplete. As recently as July 2000, 11 new and disparate species were described from tropical and subtropical Australia (Hill, K.D. and Johnson, L.A.S., 2000, Telopea 8, 503–539). From early European perceptions of them as strange, tough, unwanted trees that dominated the harsh landscape and frustrated the early agricultural development of the isolated continent of Australia, they have become taxa of worldwide importance for large-scale and small-scale planting (see Chapter 1). They now include the most widely planted hardwoods in diverse climates around the world, including the semiarid regions of North Africa, Central Asia and the Middle East, the Mediterranean regions of North Africa, southern Europe, the Middle East and California, the cool mountain regions of South America and Africa, and the tropics and subtropics of Central and South America, Africa and Asia. Eucalypts have become an integral part of the South American landscape, to the extent that they are a pervading presence in the literature of the region. In India, China and Vietnam they have become so well established that people refer to local landraces of particular species or hybrids. In the warmer climatic regions, they are important ecologically, socially and industrially. As well as helping to meet the growing world demand for cellulose fibre, timber and fuelwood, they are being used to renew the seriously depleted timber and firewood resources associated with poverty in many countries, for soil stabilisation in degraded environments and as an addition to the garden resources of subsistence farmers (see Chapter 1). This book is concerned with disease in trees growing in a wide range of situations, from native plant communities being managed for conservation purposes or mainly for timber and fibre production to intensively managed plantations. Many species of eucalypts are in the process of domestication. Increasingly, even in Australia, the trend is towards the planting of eucalypts and their manipulation by selection, breeding, clonal propagation and intensive silviculture. Seed of a great diversity of provenances collected from the wild in Australia, Papua New Guinea and Indonesia is being used in selection and breeding programs in many countries.

In Australia, there has been increasing awareness of the importance of the eucalypts in their natural environment, particularly for land conservation and protection, for conservation of native flora and fauna, and for the conservation of the ultimate repository of the vast genetic resource of eucalypt species, provenances and families adapted to a diverse range of environments. This has led to the development of forest and land management practices concerned with their protection and preservation, and the restoration of degraded eucalypt-dominated communities. The more than 700 species of eucalypts range from those adapted to the semiarid environments that dominate much of the Australian continent, to those, including some of the world’s tallest and most majestic trees, adapted to the cooler, wetter environments in the south-east and south-west of the country, to those adapted to the warm, wet environments in the northern subtropical and tropical regions (see Chapter 4). Ring counts on free-standing, single-stemmed trees in the tall forests have provided evidence of their great longevity (up to 450 years) (Hickey, J.E., Su, W., Rowe, P., Brown, M.J. and Edwards, L., 1999, Australian Forestry 62, 66–71). Although the eucalypts still dominate the Australian landscape, since European settlement there have been massive changes in the scale and condition of eucalypt forests and woodlands resulting from large-scale clearing for agriculture and urban development, introduction of exotic plants and animals, alteration to fire regimes, harvesting, and changes in hydrological balance and salinity across the landscape. Further changes to the situation of eucalypts in Australia have accompanied the planting of eucalypts in altered rural and urban environments, as individual trees, shelter belts, amenity plantings or in large plantations. These changes, relatively sudden in evolutionary terms, have led to an increased awareness of the physiological and nutritional requirements of the eucalypts (see Chapters 5 and 16), of the importance of eucalypt mycorrhizas (see Chapter 6), and of the potential destructiveness of pests and diseases. Since the 1950s, it has become increasingly apparent that many remnant native forests and woodlands are suffering ill health, with symptoms generally referred to as ‘dieback’, associated with environmental stresses and increased pest and disease pressure. Remnant trees in agricultural and grazing lands have suffered increasingly from ‘rural dieback’, a syndrome associated with increased insect attack (see Chapter 17). Large areas of forest in south-east and south-west Australia have suffered decline and, in certain forests, mass deaths caused by Phytophthora cinnamomi (see Chapter 11). Patches of forest in south-east Australia were killed by the native agaric, Armillaria luteobubalina (see Chapter 12). The early attempts at cultivation of eucalypts in plantations in Australia revealed the potential destructiveness of several highly adapted leaf pathogens (see Chapter 9). These diseases alerted the community to the dangers of increased occurrence and intensity of disease epidemics associated with the great changes wrought by European settlers on native eucalypt vegetation.

When eucalypts were first grown outside Australia in the absence of their coevolved parasites, they often appeared healthier and more vigorous than in their native lands. Later, as the plantings became more extensive, the trees began to suffer attack by non-specialist pathogens, especially in the humid subtropics and tropics. In New Zealand, they were badly damaged by leaf pathogens introduced from Australia, while in South Africa they were attacked by some pathogens which appear to have spread from local plants onto the introduced eucalypts. In South America, a destructive rust pathogen and a canker pathogen have transferred to eucalypts from local myrtaceous hosts. There are serious concerns that if these ‘new-encounter’ pathogens are introduced to Australia they could cause great damage in eucalypt-dominated vegetation. Certainly the widespread planting, often in intensive culture, of eucalypts around the world has created new opportunities for the adaptation and spread of pathogens and pests.

As a result of the occurrence of disease problems in both native eucalypt communities and plantations outside Australia, there has been an upsurge in interest in the pathology of eucalypts over the last 40 years, as reflected in the burgeoning literature on the subject. It is an opportune time to review knowledge of the biotic and abiotic factors affecting the health of eucalypts, and to bring together the disparate literature on the subject as a basis for further research. With this in mind, Geoff Marks initiated the writing of this book. His death in 1990 prevented his participation beyond the planning stage, but the eventual production of the book is a tribute to his enthusiasm for the field of eucalypt health, his 27 years of research on diseases of eucalypts, particularly dieback associated with Phytophthora cinnamomi, and the encouragement he gave to others.

This book is intended not only as a catalogue of current knowledge about the diseases of eucalypts but also as a handbook to facilitate further research into their biology and management. The book is concerned with the health of eucalypt-dominated plant communities in Australia, and of small social plantings and large industrial plantations around the world, not just with a narrow account of diseases of the trees. The rapid expansion of eucalypt planting, first outside and lately within Australia, and the more intensive management of native forests have resulted in a growing interest in the physiology, nutrition, adaptation, genetics, ecology, silviculture and management of the eucalypts. While the book has a strong emphasis on disease in production forests, it also addresses disease in native eucalypt-dominated forests and woodlands and in remnant or isolated, planted eucalypts.

The book concerns a complex and wide ranging field. Accordingly, it includes a substantial introduction to the biology, ecology and physiology of the eucalypts (Section I) as a basis for further discussion of particular diseases (Section II) and the management options for these diseases in natural, semi-natural and planted communities (Section III). In particular, the genetic diversity of the eucalypts and their adaptation to a wide climatic and edaphic range in Australia and nearby countries is discussed in some detail in Chapter 2 and Chapter 4 as a basis for development of disease management through matching of genotypes to sites and selection of disease resistant planting stock. This book should serve as a timely reminder that the eucalyptdominated communities across Australia and in nearby countries are an invaluable repository of the diverse genetic resource of the eucalypts. In Chapter 3, the growth habits and silviculture of eucalypts is discussed in relation to development of management strategies for maintaining forest health. The ecology of eucalypt regeneration in native communities is introduced in Chapter 4 as a basis for developing knowledge and management expertise in control of diseases in the most disease-prone phases of forest management, namely regeneration in native forests, and production of planting stock and early establishment in plantations. Harvesting and regeneration activities in native forests often result in dense seedling regeneration which may suffer severe epidemics of foliar disease not unlike those expected in crowded plantations. The physiology of eucalypts in relation to their response to stresses including pathogens is introduced in Chapter 5 in anticipation of future research on the physiological effect of diseases of eucalypts and how this might be ameliorated. Chapter 6 reviews knowledge of the mycorrhizas of eucalypts, a subject of great importance to the nutrition and health of the trees. Mycorrhizas are of concern to all involved in management of eucalypt forests and are of particular interest to anyone with a mycological interest in the forests, particularly plant pathologists who are often involved in research into mycorrhizas as well as diseases. This chapter provides a basis for further research on manipulation of mycorrhizas for adaptation of eucalypts to new sites and for combating soilborne diseases. Knowledge of the biology of eucalypts is crucial for developing disease management practices, especially for diseases of native forests and woodlands, which often have complex etiology and can be ameliorated only by modification of normal silvicultural practices.

The chapters in Section II include much background biology of the diseases and their causal organisms, along with discussion of the pathology and management of the diseases. This allows the chapters to stand alone as an introduction to the diseases. In Chapter 9, on foliar diseases, it was necessary to include much taxonomic detail of the causal organisms, reflecting the early stage of development of research into these diseases. Throughout the book, the presentation of Latin binomials of fungal species and their authorities follows Authors of Fungal Names by P.M. Kirk and A.E. Ansell, published by the International Mycological Institute, Kew, in 1992. However, the style of R.K. Brummitt and C.E. Powell (1992, Authors of Plant Names, Royal Botanic Gardens, Kew) has been followed in omitting gaps between initials and surnames. The inclusion of taxonomic details of the fungi referred to in the literature has helped to highlight and clarify discrepancies in the naming of fungi. Much synonymy exists and the organism index, researched and compiled by B.N. Brown, serves as an invaluable guide to the current state of nomenclature. Authorities and Australian common names for eucalypt species are listed in the Index. In Chapter 15, on phanerogamic parasites, much underlying ecology of the parasites is presented as a basis for their management in remnant eucalypt vegetation and on forest verges in Australia. Management of nutritional disorders requires knowledge of the physiological role and interactions of various nutrients (see Chapter 16).

In Section III, the options and constraints for management of disease in both native forests and plantations are discussed (see Chapter 18). In Chapter 19, detailed approaches to management of disease in native forests are discussed, with particular emphasis on management of dieback caused by Phytophthora cinnamomi, which has been central to forest pathology in Australia for four decades. A particular instance of intensive management of eucalypt dieback in association with bauxite mining in the Eucalyptus marginata forests of southwest Australia is reviewed in Chapter 20. Finally, the more intensive disease management practices in eucalypt nurseries (see Chapter 21) and plantations (see Chapter 22) are reviewed from an international perspective.

Although the book provides a comprehensive review of the state of knowledge of eucalypt diseases, it also shows that our knowledge of most diseases is preliminary—there is much to be learnt. We hope that this book will provide a basis for more intensive studies of the nutrition, adaptation and diseases of the eucalypts, leading to improved health, productivity and sustainability of these species in native eucalypt communities, and in both large plantations and smaller plantings around the world.

CONTRIBUTORS 

D.H. Ashton

Department of Botany, La Trobe University, Bundoora, Vic. 3083, Australia

Email: [e-mail]

David Ashton completed his PhD in 1956 at the University of Melbourne on the ecology of Eucalyptus regnans and then undertook further studies at Cambridge University, in Germany and in the USA. In 1960, he took up a lectureship in ecology in the School of Botany at the University of Melbourne, where he continued research on the ecology of E. regnans and diversified into studies of a wide range of ecosystems from coastal heath to alpine-antarctic. From 1975 to 1986 he collaborated on ecological studies of the forests of Chile and Argentina. He is an Associate of the School of Botany and also a Research Fellow in the Department of Botany, La Trobe University.

C.L. Beadle

Cooperative Research Centre for Sustainable Production Forestry and CSIRO Forestry and Forest Products, GPO Box 252-12, Hobart, Tas. 7001, Australia Email: [e-mail]

Chris Beadle obtained his PhD in Botany from the University of Aberdeen in 1977. Since 1983 he has worked for CSIRO Forestry and Forest Products in Hobart, where he is now a Principal Research Scientist and Program Manager of the Sustainable Management Program in the Cooperative Research Centre for Sustainable Production Forestry.

B.N. Brown

15 Harefield Street, Indooroopilly, Qld 4068, Australia Email: [e-mail]

Bruce Brown obtained his BAgSc (Hons) from the University of Queensland in 1963 and his PhD from the University of Auckland in 1978. He was a Forest Pathologist with the Queensland Department of Forestry (subsequently the Forest Service of the Queensland Department of Primary Industries) from 1963 until 1991. He studied a wide range of forest diseases in nurseries, plantations and natural forests. He was heavily involved in the control of nursery diseases, and investigated Phytophthora cinnamomi in forest nurseries, Pinus and Eucalyptus plantings and natural vegetation (including tropical rainforests) of Queensland. Recently he has worked as consultant on several projects.

G.A. Chilvers

23 Keats Street, Byron Bay, NSW 2481, Australia Email: [e-mail]

Graham Chilvers obtained his BScAgr from the University of Sydney, majoring in Plant Pathology under Professor N.H. White, and his PhD at the Australian National University, working on mycorrhizas of eucalypts under Professor L.D. Pryor. He spent two periods of sabbatical leave at the University of Oxford working on mycorrhizas with Professor J.L. Harley. For most of his career he was a Senior Lecturer in the Botany Department, Australian National University. His major research interest was in eucalypt mycorrhizas, but he also studied and lectured in diverse areas of plant-microbe relationships and microbial ecology.

I.J. Colquhoun

Alcoa of Australia, Booragoon, WA 6154, Australia Email: [e-mail]

Ian Colquhoun is a Senior Research Scientist with the Environmental Department of Alcoa World Alumina Australia. He received his BSc in Botany from the University of Glasgow in 1976, and his PhD from the University of Western Australia in 1986 for a dissertation on the physiology of Australian native plants. In 1980, he joined Alcoa to supervise a project on the hydrological balance of revegetated minepits. In 1989, his responsibilities extended to the interaction between the hydrology of rehabilitated minepits, tree physiology and Phytophthora root rot. His present responsibilities include the development of disease control measures for mining, coordinating plant pathology research projects and supervising plant physiology projects based in the jarrah forest and rehabilitated minepits.

P.W. Crous

Department of Plant Pathology, University of Stellenbosch, Private Bag XI, Matieland 7602, South Africa

Email: [e-mail]

Pedro Crous did his MSc(Agric) on leaf diseases of Eucalyptus, which set the stage for much of his future research. He obtained his PhD(Agric) in 1992, dealing with Cylindrocladium and related fungi, with specific reference to woody hosts. He has since continued studies on this group, but also initiated projects on Mycosphaerella, Botryosphaeria and their anamorphs. His main interests are anamorph/ teleomorph connections, and the integration of DNA and morphological data in the phylogeny of fungi. He is Professor of Mycology and Chair of the Department of Plant Pathology at the University of Stellenbosch. He is also the President of the Southern African Society for Plant Pathology.

E.M. Davison

School of Environmental Biology, Curtin University, GPO Box U 1987, Perth, WA 6001, Australia Email: [e-mail]

Elaine Davison received her BSc Honours from the University of Bristol in 1963 and her PhD from the same university in 1967. From 1968 to 1972 she worked as a Plant Pathologist at the Botanic Garden and at the Waite Agricultural Research Institute in Adelaide. In 1979, she was a post-doctoral research fellow at the University of Oxford. From 1979 to 1986 she worked as a Mycologist/Plant Pathologist with the Department of Conservation and Environment, and from 1986 to 1995 she was a Principal Research Scientist at the Department of Conservation and Land Management in Western Australia, concerned with diseases of eucalypts. She is now a Senior Research Associate and works as a consultant based at Curtin University of Technology.

J.C. Dianese

Departmento de Fitopatologia, Universidade de Brasilia, 70919 Brasilia, DF, Brazil Email: [e-mail]

Jose Dianese obtained his BS in agronomy from the Universidade Federal de Viçosa and his MS and PhD in plant pathology from the University of California, Davis. Since 1971 he has lectured at the University of Brasilia where he is currently Professor and Chairman of the Department of Plant Pathology. He has conducted research on a wide range of diseases of agricultural and forest species, with an emphasis on diseases of eucalypts, especially guava rust and bacterial wilt.

M.A. Dick

New Zealand Forest Research Institute, Private Bag 3020, Rotorua, New Zealand Email: [e-mail]

Margaret Dick obtained a BSc in Botany and has worked since 1972 as a forest pathologist with the New Zealand Forest Research Institute, concentrating on fungal diseases. She has studied foliage diseases of eucalypts in plantations, root diseases of pine, and more recently Cyclaneusma needle cast of Pinus radiata. She has also been involved in pest risk analysis, particularly of the threat posed by pine pitch canker to plantation forests in New Zealand. For over 20 years she has supervised the forest disease diagnostic service. This has included identification and monitoring of foliage diseases on eucalypt species during their testing for adaptation to local conditions.

P.E. Elliott

WMC Resources Ltd, QV1 Building, 250 St George’s Terrace, Perth, WA 6000, Australia Email: [e-mail]

Peter Elliott obtained his MSc in Natural Resource Management from the University of Western Australia. In 1990 he was the senior environmental scientist with Alcoa and coordinated the development of the intensive dieback management program. This involved him in developing strategies, policies and procedures for management of operations in jarrah forests, in consultation with a wide range of Alcoa employees and government agencies. As Corporate Manager—Environmental Systems, he was later responsible for the development of Environmental Management Systems for WMC Resources Ltd. He has recently been appointed Manager—Planning and System Services in the Corporate Human Resources and Development Group of the company.

F.A. Ferreira

Departmento de Fitopatologia, Universidade Federal de Viçosa, 36571.000 Viçosa, Minas Gerais, Brazil Email: [e-mail]

Francisco Ferreira is a forest pathologist with over 25 years of experience in teaching, research and extension on the etiology and management of forest diseases in Brazil, including diseases on eucalypts, pines and rubber. He has been concerned with nursery diseases, rust diseases and defence mechanisms in the bark and xylem as they relate to the diagnosis and control of biotic and abiotic trunk diseases. He has undertaken extension activities related to the diagnosis and management of diseases of eucalypts for both private companies and public institutions in Brazil and other countries in South America and Europe. He is currently Professor of Forest Pathology at the Federal University of Viçosa.

R.G. Florence

Department of Forestry, Australian National University, GPO Box 4, Canberra, ACT 2601, Australia Email: [e-mail]

Ross Florence graduated from the Australian Forestry School and the University of Queensland in 1953 and worked on silviculture of native forests with the Queensland Forest Service. He obtained his PhD from the University of Sydney in 1961 for studies on the ecology of native forests. He joined the Department of Forestry of the Australian National University in 1965 where he lectured in silviculture, forest ecology, and planning and policy. He wrote Ecology and Silviculture of Eucalypt Forests, published by CSIRO Publishing in 1996.

P.D. Gadgil

New Zealand Forest Research Institute, Private Bag 3020, Rotorua, New Zealand Email: [e-mail]

Peter Gadgil obtained his PhD in the area of microbial ecology from the University of Cambridge in 1962 and has been a forest pathologist with the New Zealand Forest Research Institute since 1965. His main areas of work have been needle diseases of Pinus radiata (Dothistroma needle blight, Cyclaneusma needle cast), stem decay in Eucalyptus spp. and, with Ruth Gadgil, the influence of mycorrhizal fungi on litter decomposition in coniferous forests. More recently, he has concentrated on the eradication of Dutch elm disease from New Zealand, methods of forest health surveillance and the investigation of pathways by which forest pests and pathogens can reach New Zealand.

G.C. Johnson

10 Glendowan Road, Mt Waverley, Vic. 3149, Australia

Gary Johnston completed his BScFor(Hons) and MSc(Forestry) at the University of British Colombia and obtained his PhD from the Australian National University where he studied under Professor D.M. Griffin and Dr W.A. Heather. He taught forestry at the University of Melbourne before taking up a position as a research scientists with CSIRO Forestry and Forest Products in Clayton, Vic., where he worked for 21 years until 2000, specialising in decay of wood and natural durability of timber.

P.J. Keane

Department of Botany, La Trobe University, Bundoora, Vic. 3083, Australia Email: [e-mail]

Philip Keane obtained a BAgSc(Hons), specialising in plant pathology, from the University of Adelaide, and a PhD from the University of Papua New Guinea for studies on the cause and control of a dieback disease of cocoa. Since 1975 he has lectured in botany, environmental biology, mycology and plant pathology at La Trobe University where he is now an Associate Professor. His research interests include foliar diseases of eucalypts and diseases of a wide range of agricultural crops, with a special interest in resistance to disease, biological control and plant diseases in the tropics.

G.A. Kile

CSIRO Forestry and Forest Products, PO Box E4008, Kingston, Canberra, ACT 2604, Australia Email: [e-mail]

After completing his BAgrSc(Hons) and PhD at the University of Tasmania, Glen Kile undertook research on diseases in native forests in Australia, particularly Armillaria and stem rot fungi in eucalypts, Chalara australis in Nothofagus forests, and some dieback diseases of complex etiology. He identified Armillaria luteobubalina as a major pathogen in eucalypt forests, amenity plantings and horticulture in Australia and conducted taxonomic and population studies of Armillaria. He was appointed Director of the Cooperative Research Centre for Temperate Hardwood Forestry in 1991, Chief of CSIRO Division of Forestry in 1992 and Chief of CSIRO Forestry and Forest Products in 1996. He is a member of the Standing Committee on Forestry of the Australian Ministerial Council on Forestry, Fisheries and Aquaculture, and Chairman of its Committee on Forest Health. He is a member of the editorial boards of Australasian Plant Pathology and the European Journal of Forest Pathology.

K.M. Old

CSIRO Forestry and Forest Products, PO Box E4008, Kingston, Canberra, ACT 2604, Australia Email: [e-mail]

Ken Old obtained his BSc(Hons) in agricultural botany from the University of Nottingham in 1961 and his PhD from the University of Minnesota in 1964. He lectured in plant pathology, mycology and soil microbiology at Dundee University from 1964 to 1978. He joined CSIRO Forestry and Forest Products in 1978 and was Assistant Chief from 1992 to 1999. He is currently a Chief Reseach Scientist. His main research interests have included genetic variation in Phytophthora cinnamomi, canker diseases of eucalypts, foliar pathogens of eucalypts and acacias in plantations in tropical Australia and south-east Asia, and stem defect in regrowth eucalypt forests in south-east Australia.

R.F. Park

University of Sydney, Plant Breeding Institute Cobbitty, PMB 11, Camden, NSW 2570, Australia Email: [e-mail]

Robert Park obtained his BSc(Hons) and PhD from La Trobe University where he studied the pathology of Mycosphaerella species infecting eucalypts in southeast Australia. He is currently a Senior Research Fellow at the University of Sydney, Plant Breeding Institute, Cobbitty, where he works as a plant pathologist concerned mainly with ecological aspects of cereal rusts and breeding of cereals for resistance to rusts. He was awarded an Alexander von Humbolt Fellowship in 1995 and spent one year at the Technical University of Munich studying European populations of wheat leaf rust. Since his student days he has maintained an interest in the diversity of the foliar pathogens of eucalypts.

L.A. Pederick

17 Yanigin Drive, Glen Waverley, Vic. 3150, Australia

Leon Pederick obtained his BScFor and PhD from the University of Melbourne and worked as a research scientist for the forest service of the Victorian Government from 1958 to 1993. He specialised in genetics of forest trees and for over 30 years led a breeding program for Pinus radiata. He also undertook extensive provenance and progeny trials with several eucalypt species, especially Eucalyptus nitens. He is a Fellow of the Institute of Foresters of Australia, and was awarded the Institute’s N.W. Jolly Medal for 1991.

F.D. Podger

19 Stanstead Crescent, Marangaroo, WA 6064, Australia

Frank Podger obtained a BSc(For) from the University of Western Australia, a DipFor from the Australian Forestry School, Canberra, an MScFor from the University of Melbourne, and a PhD from the University of Auckland. His early career with the WA Forests Department involved field training in forest management in eucalypt forests. In 1959, under federal employ he researched the cause of a destructive epidemic of dieback in the jarrah forests, first reporting in 1964 its association with the exotic pathogen Phytophthora cinnamomi and publishing proof of its cause in 1972. For this he received an inaugural Scientific Achievement Award from IUFRO. He has since studied diseases of native vegetation in all States of Australia and has also had an interest in fire effects ecology and its interactions with Ph. cinnamomi. In the last decade he has consulted to governments in Tasmania and Western Australia on management for amelioration of disease in native forests and its sociopolitical implications. From 1993 to 1996 he chaired a review of management of Phytophthora root rot in Western Australia. In 1999, he produced a source document on which was based a National Threat Abatement Plan for amelioration of the threat posed to conservation values by the epidemic of Phytophthora root rot.

B.M. Potts

Cooperative Research Centre for Sustainable Production Forestry, School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tas. 7001, Australia Email: [e-mail]

Brad Potts completed his PhD at the University of Tasmania in 1983 where he is currently a Senior Lecturer in the School of Plant Science and Manager of the Genetic Improvement Program of the Collaborative Research Centre for Sustainable Production Forestry. Within this program he is leader of the research project on the reproductive biology and genetics of eucalypts and works closely with quantitative and molecular geneticists at the University of Tasmania on the natural history and breeding of eucalypts. He has worked in and maintains active research collaboration with scientists in France, Chile and the USA and has specialised in studies of hybridisation, genetics and evolution of the eucalypts.

N. Reid

Ecosystem Management, University of New England, Armidale, NSW 2351, Australia Email: [e-mail]

Nick Reid completed a BSc(Hons) and PhD in Botany at the University of Adelaide. His early research career spanned ornithology, rangeland ecology and the reproductive and population biology of arid zone mistletoes. An academic posting in Mexico led to ecological research on the vegetation dynamics, phenology and ethnobotany of subtropical thornscrub. He is currently Associate Professor and Convenor of Ecosystem Management in the School of Rural Sciences and Natural Resources at the University of New England, where he teaches agroforestry, park and wildland management, and sustainable land management. His current research includes the role of trees in farm ecosystems, native vegetation management in rural and wildland environments, revegetation technologies and mistletoe management.

J.K. Sharma

Kerala Forest Research Institute, Peechi Trichur 680 653, Kerala, India Email: [e-mail]

Jyoti Sharma obtained his PhD in Botany (Plant Pathology) from Agra University and was a lecturer at Agra College for eight years. Later, he spent five years at the Australian National University, Canberra, doing post-doctoral research in forest pathology. He joined the KFRI in 1978 as the Scientist-in-Charge, Plant Pathology Division. He was appointed Research Coordinator of the Institute in 1996 and Director in July 2000. He is presently the IUFRO Working Party Coordinator on Diseases of Tropical Plantations. He has had extensive research and consulting experience on diseases and mycorrhizas in eucalypt plantations. He served as an Expert Member on an FAO/IPGRI committee to frame guidelines for the safe movement of eucalypt and pine germplasm and is a Fellow of the Indian Phytopathological Society.

B.L. Shearer

Department of Conservation and Land Management, 50 Hayman Road, Como, WA 6152, Australia Email: [e-mail]

Bryan Shearer obtained a BScAgric(Hons) from the University of Western Australia and a PhD from the University of Minnesota, USA. He is a Principal Research Scientist in the CALM Science Division of the Department of Conservation and Land Management of Western Australia and Adjunct Associate Professor in the Division of Science at Murdoch University. He has investigated the impact, epidemiology and control of Phytophthora species, Armillaria luteobubalina and canker fungi in native plant communities for over 20 years. His current research interests centre on the ecology and control of plant diseases in conservation areas of south-west Western Australia.

J.A. Simpson

Forest Research and Development Division, State Forests of NSW, PO Box 100, Beecroft, NSW 2119, Australia Email: [e-mail]

Jack Simpson is Senior Forest Pathologist with the Research and Development Division of State Forests of New South Wales, where he has worked for almost 20 years. He obtained an MAgSc from the University of Adelaide for a thesis on mycological aspects of the decomposition of litter of Pinus radiata. During his career Jack has worked on diverse forest disease problems in South Australia, New South Wales, Western Australia, Papua New Guinea and Fiji. He is Chair of Research Working Group 7 (Forest Health), a member of the Forest Health Committee, and the forestry observer on the Plant Health Committee of the Standing Committee on Forestry. He is past president of the Australasian Mycological Society. His research interests include eucalypt foliage pathogens, stem decays in living trees, quarantine issues relating to management of incursions of quarantine pests and imports of wood, and forest declines.

I.W. Smith

Centre for Forest Tree Technology, Department of Natural Resources and Environment, PO Box 137, Heidelberg, Vic. 3084, Australia Email: [e-mail]

Ian Smith obtained a BSc(Hons) from Monash University and is a forest pathologist in the Centre for Forest Tree Technology of the Department of Natural Resources and Environment. He is responsible for investigating the productivity and ecology of native forests, and the biology and control of diseases that threaten the productive capacity of native forests, softwood and hardwood plantations and nurseries. He has over 20 years of experience in the field of forest pathology research in Victoria, much of which was centred on eucalypt dieback caused by Phytophthora cinnamomi.

P. Snowdon

CSIRO Forestry and Forest Products, PO Box E4008, Kingston, Canberra, ACT 2604, Australia Email: [e-mail]

Peter Snowdon is a Principal Research Scientist with the Plantation and Farm Forestry Program of CSIRO Forestry and Forest Products. He majored in plant pathology at the University of Sydney and gained his MSc from the Australian National University for a study of boron nutrition in pines. He has 40 years of experience in various aspects of forest nutrition, including the use of visible symptoms and chemical analyses of soil and foliage samples for identification of nutrient deficiencies and toxicities. He has also been involved in research into the effects of environmental factors such as drought and frost on the growth and health of plantation species.

J.W. Turnbull

CSIRO Forestry and Forest Products, PO Box E4008, Kingston, Canberra, ACT 2604, Australia Email: [e-mail]

John Turnbull has a BSc degree in forestry from the University of Wales and a PhD in eucalypt genecology from the Australian National University. As a Senior Principal Research Scientist at CSIRO Forestry and Forest Products he was involved for over 25 years in the exploration and utilisation of eucalypt genetic resources in Australia and many other countries. Subsequently he was Chief Scientist at the Center for International Forestry Research in Indonesia. He is currently based at the Australian Tree Seed Centre, CSIRO Forestry and Forest Products, Canberra.

T.J. Wardlaw

Forestry Tasmania, GPO Box 207B, Hobart, Tas. 7001, Australia Email: [e-mail]

Tim Wardlaw obtained a BScHons and is completing a PhD at the University of Tasmania. He is Senior Forest Pathologist with Forestry Tasmania. In a career spanning 20 years he has investigated a wide variety of forest diseases including eucalypt crown dieback diseases with complex etiologies, needle cast diseases of Pinus radiata and stem decay of eucalypts in native forests and plantations. Recently much of his work has been focused on quantifying the effects of diseases and developing management strategies to reduce disease losses. He has overseen the introduction and development of health surveillance of eucalypt and pine plantations in Tasmania.

M.J. Wingfield

Forestry and Agricultural Biotechnology Institute, University of Pretoria, 74 Lunnon Road, Hillcrest, Pretoria, Republic of South Africa 0002 Email: [e-mail]

Mike Wingfield has a PhD from the University of Minnesota and is the Director of the Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa. He has 20 years of experience in research on diseases of forest trees and has specialised in the identification and management of diseases of eucalypts, pines and wattles grown as exotics in plantations. He has provided advisory services to forestry companies in South Africa, South and Central America, and south-east Asia.

Z. Yan

Plant Research and Development Services, Agriculture Western Australia, Baron Hay Road, South Perth, WA 6151, Australia

Zhaogui Yan studied agricultural science at the Central China University of Agriculture and completed his PhD in mistletoe ecology at Flinders University, South Australia. He currently works for Agriculture Western Australia where his principal research interests are managing annual ryegrass toxicity through biological control, the population dynamics of rangeland plants under various climatic and grazing regimes, and the ecological interactions between mistletoes and their hosts and dispersers.

CHAPTER 1

ECONOMIC AND SOCIAL IMPORTANCE OF EUCALYPTS

J.W. Turnbull

SUMMARY

For thousands of years eucalypts have been of critical importance in the economy of indigenous Australians. In the last 200 years eucalypts have passed from being a botanical curiosity and nuisance to the early European settlers in Australia, to trees of importance in the local economy, to one of the world’s most important and widely planted forest species. Eucalypts have valuable wood and pulp characteristics and many useful silvicultural properties including high growth rates, adaptability to a wide range of soils and climates, coppicing ability and a tendency not to spread as a weed. In Australia, eucalypt-dominated native forest and woodland communities cover about 124 million hectares but wood and pulp production is restricted to about 13 million hectares. It is estimated that there will be 20 million hectares of eucalypt plantations outside Australia by the year 2010. At present there are more than 10 million hectares in the tropics alone, mainly in South America and Asia. Since the early 1980s, eucalypt planting has expanded rapidly in many parts of the world, including Australia. This expansion has been driven by the world demand for pulpwood, but eucalypts are also being planted widely as a source of charcoal, fuelwood and building materials and for land conservation. The trees can provide a source of financial security for small farmers. Great benefits have accrued from clonal selection and breeding of eucalypts and from more intensive management practices, in which Brazil has led the way. However, it is important to recognise the increased risk of disease epidemics associated with the movement of pathogens to new areas and the establishment of densely planted, genetically homogeneous plantations. Outbreaks of disease in plantations and native forests have stimulated much recent research into the diseases of eucalypts.

1.1 Introduction

The eucalypts (genera Eucalyptus, Corymbia, Angophora), being by far the dominant tree over most of the Australian landscape, have been critical to the economy of indigenous Australians, directly supplying fuel, building materials, medicine and resins, and being habitat for the animals that contributed greatly to their diet.

In the late eighteenth century when eucalypts first came to the attention of the scientific world and the French botanist, Charles Louis L’Héritier De Brutelle, applied the name Eucalyptus to an Australian tree, there was little appreciation of the potential of eucalypts to become a major source of industrial forest products. The wood was difficult to saw and season and it was commonly considered to have value only as firewood or as poles. Remarkably, at the beginning of the twenty-first century the natural eucalypt forests are a major source of forest products, and eucalypts have become the most widely planted hardwood species in the world.

1.2 Eucalypts in native forests

Eucalypts dominate 124 million hectares of Australia’s natural forests and woodlands (Australian Bureau of Agricultural and Resource Economics 1997) (see Chapter 4) and they have great cultural and environmental significance, as well as being a valuable source of wood products. Most of this area is eucalypt woodland. Only about 28 million hectares is potentially productive forest (Australian Forestry Council 1989). Production of wood for industrial purposes is restricted to about 13 million hectares by factors such as lack of accessibility and conservation reserves (Commonwealth of Australia 1997). Beyond Australia there are small areas of natural eucalypt forests in Indonesia, Papua New Guinea and the Philippines but these are of relatively little economic significance, even locally.

When European settlement began in Australia in 1788, trees were considered to be a hindrance to development. Clearing of land for agriculture was essential and large areas of eucalypts were felled. About half of Australia’s forests have been cleared or severely modified by selective logging or uncontrolled fires (Wells et al. 1984; Resource Assessment Commission 1992). Attitudes to the forests changed markedly around the start of the twentieth century and State forest services were established to manage public forests for perpetual timber production. By the 1930s the concept of ‘multiple use forestry’ was recognised and forests were dedicated for watershed protection, recreational use and the conservation of native wildlife and flora, in addition to timber production (Carron 1985).

The supply of eucalypt timber has generally exceeded demand in Australia and there has been little incentive to manage eucalypts intensively for wood production (Kerruish and Rawlins 1991). In most States the harvest of eucalypt sawlogs increased progressively from about 1930 but is now declining from peaks reached between 1955 and 1980. Today, eucalypt forests meet about half of Australia’s domestic requirements for forest products, the remainder being imported or derived from local plantations of softwood (mainly Pinus species). However, pulpwood production from eucalypt forests increased dramatically from the early 1970s, particularly in Tasmania, Western Australia and New South Wales, with the development of an export market for Australian eucalypt woodchips to meet increased demands for printing, writing and tissue papers.

The volume harvested has remained fairly stable through the 1990s. In 1997–98 some 10.3 million cubic metres of native hardwoods (mainly eucalypts) were removed for timber and woodchips and it is predicted that this level will be maintained until 2005 (Australian Bureau of Agricultural and Resource Economics 1999). In 1997, exports of hardwood chips reached 2.5 million tonnes (bone dry). Woodchip, including softwood chips, has generally accounted for just over half of the value of Australian forest product exports in the 1990s and reached a record $646 million in 1997–98 (Australian Bureau of Agricultural and Resource Economics 1999). However, the wood and wood products industry contributes only about 1% of Australia’s gross domestic product.

While the eucalypt wood industry is small within the overall Australian economy, the various sectors of the industry together employ about 40 000 people and have great significance in providing employment and economic activity in particular regions (Resource Assessment Commission 1991). Eucalypt growing, harvesting and processing are the major activities of several small rural communities.

There seems little doubt that the natural eucalypt forests will continue to have considerable economic significance in Australia. By the year 2005 the annual hardwood removals (mainly eucalypt) from Australia’s native forests will be 10.1 million cubic metres (Australian Bureau of Agricultural and Resource Economics 1999). There are also excellent opportunities for the more intensive management of some of the higher-yielding temperate forests in Australia, and a young regrowth eucalypt resource of about 300,000 ha is possibly amenable to intensive management (Wells 1991). The area under eucalypt plantations is being expanded to meet pulpwood needs and possibly some sawlog requirements. As a result of an active eucalypt plantation program with E. globulus and E. nitens, the area of hardwood plantations in Australia rose from 125,000 hectares in 1994 to 287,000 hectares in 1998 (Cromer et al. 1995; Wood et al. 1999).

In addition to the economic value of the native eucalypt forests, they have great societal, cultural and environmental significance. Eucalypt forests and woodlands dominate the Australian landscape. They hold particular significance for Aboriginal peoples (Resource Assessment Commission 1991). They are critical for the protection of soil, maintenance of hydrological balance and the survival of wildlife. Excessive clearing of eucalypts and their associated communities has led to decline of remnant trees and salinity problems in many areas. The native forests and woodlands are also the ultimate repository of the great genetic diversity of the eucalypts. In response to community attitudes and changes in government policies, efforts are increasing to modify forest practices to better address conservation values and the maintenance of biological diversity (Turnbull 1996).

Although many of the environmental effects of more intensive culture of eucalypts are incompletely understood, there is no doubt that environmental effects will result from the intensification of forestry practices. However, in most cases the costs imposed on the environment by sustainable harvesting and extension of eucalypt planting will be less than those associated with agriculture or other types of intensive land management on similar land. Benefits of intensive culture of eucalypt plantations will accrue from the reduced land area required for wood and pulp production, the use of a renewable resource and from the broader socioeconomic effects of such activity (Nambiar and Brown 1997).

1.3 Eucalypts as exotics

Outside Australia, eucalypts were initially regarded as botanical curiosities and were sought by botanical gardens and private aboreta in Europe. Once in cultivation, the potential of some eucalypt species to grow rapidly and produce straight stems was recognised and the botanical gardens of southern Europe became centres for the secondary dispersal of eucalypts to other parts of the world, especially Latin America and Africa. Later in the nineteenth century, eucalypts were introduced directly from Australia to many parts of the world. Some were planted for their ornamental value, and others for windbreaks, land reclamation and leaf-oil production. In countries such as Brazil and South Africa, eucalypts were planted along railway lines to provide fuel for woodburning locomotives.

The reasons for planting eucalypts have changed significantly, and the end uses to which the various species have been applied are diverse. Eucalypts provide sawn timber, mine props, poles, firewood, pulp, charcoal, essential oils, honey, tannin, shade and shelter (Hillis and Brown 1983). The eucalypt genera Eucalyptus and Corymbia have many favourable characteristics including high growth rates, wide adaptability to soils and climates, ease of management through coppicing, valuable wood properties and absence of any tendency to spread as weeds in most environments. Only a relatively few species from the many in the genera are preferred for fuelwood, pole or pulpwood plantations. The particular species planted depend on the climate.

Reliable global estimates for areas of planted eucalypts are difficult to obtain, but published reports (e.g. Davidson 1995) suggest that there were close to 14 million hectares at the end of 1993. Over 90% of these forests have been established since 1955 and about 50% since the mid 1980s (Turnbull 1991). There were over 10 million hectares of tropical eucalypt plantations at the end of 1990, principally in tropical America (4 million ha) and tropical Asia (5 million ha) (Food and Agriculture Organization 1993). The American statistic is dominated by Brazil where there are 3.2 million hectares (EMBRAPA 1996), including part of an area of 2.9 million hectares approved for plantation development using government incentives between 1967 and 1984 (Iuseum et al. 1988; Bazett 1993). In tropical Asia, India has over four million hectares including trees planted in various configurations on farms (Davidson 1995). In addition, there are substantial plantations in countries with more temperate climates including Chile 180,000 hectares, China 670,000 hectares, Morocco 200,000 hectares, Portugal 500,000 hectares, South Africa 538,000 hectares and Spain 350,000 hectares (Davidson 1995).

Increased areas of eucalypt plantation are projected in several countries. Plantings will continue in Brazil but not at the very high rates of the recent past as there will be more effort to increase the productivity and quality of existing areas. In Portugal too, highly productive clonal plantations of E. globulus are being developed. Both China and India have active reforestation programs, and although there has been some resistance to eucalypt plantations in the latter, the great demand for wood and restrictions on harvesting in native forests will undoubtedly ensure that planting continues.

In recent years, eucalypt planting has accelerated in several tropical countries, although extensive planting of eucalypts in the lowland humid tropics has been inhibited by a high incidence of pathogens and insect pests that reduce productivity. Only a few eucalypt species, such as E. deglupta, E. pellita and E. urophylla, are adapted to hot, humid conditions (Werren 1991). Planting of other species tends to result in severe damage by foliar diseases (e.g. Cylindrocladium spp.) associated with trees under stress (see Chapter 9). Despite this, about 200,000 hectares of E. camaldulensis have been established in Thailand (Pousajja 1996) and there are major planting programs in the Congo (Bouillet et al. 1999) and in Vietnam (Tran Xuan Thiep 1996). There are also active plantation programs in the more temperate areas such as those in South America especially in Chile, Paraguay and Uruguay. ‘Opportunities to increase world wood supply in the future will depend on plantations as a consequence of the likely static or decreasing supply from natural forests through deforestation, past overexploitation, greater reservation for non-wood uses or values, and increased costs of access and extraction’ (Kile 1999). If this scenario is correct, then the current trend to increase the area of eucalypt plantations will continue and the total area will exceed 20 million hectares by 2010.

1.4 Industrial eucalypt plantations

There is no sector of world forestry that is expanding as rapidly as the industrial use of eucalypts. Most plantations are being established to provide medium-density to low-density short-fibred pulp for paper. Global short-fibre pulp consumption is about 13 million tons per annum and is growing at 3.9% annually (World Resources Institute 1998). Plantation-grown eucalypt wood is usually harvested after 5 to 10 years and provides a uniform material with high brightness, and good opacity and bulk which make the pulp very suitable for the production of copying, printing, writing and tissue papers. Demand for these products is rising and with it the demand for eucalypt pulp.

Brazil is the largest producer of eucalypt pulp: its plantations, mainly of E. grandis, yield annually over two million tons of bleached pulp out of a total world production of about five million tons (World Resources Institute 1998). Portugal was the first country to produce eucalypt sulphite pulp in 1906 (Rolo 1988). Increasing interest over the past 20 years has brought E. globulus to prominence as a major source of income in the Portuguese economy. Portugal is the world’s second largest producer of eucalypt bleached pulp and the pulp industry accounts for the majority of Portuguese forestry exports. Other major eucalypt pulp producers are Chile (E. globulus), Morocco (E. camaldulensis), Spain (E. globulus) and South Africa (E. grandis).

Very high levels of investment are required for the pulp and paper industry. In Chile, private investment in forestry was about US$4 billion in 1996 and 15% of these funds were invested in eucalypts. Another example of the high level of investment in the eucalypt pulp industry is the Brazilian company, Aracruz Celulose S.A. Since 1973 the company has invested heavily in research, plantation management and processing plant. Tree improvement with an emphasis on clonal forestry increased the productivity of plantations from 5.9 to 10.9 tonnes per hectare per annum (Bertolucci et al. 1995). The company invested US$1.15 billion in 1990 in an expansion of its pulp mill to lift production to one million tonnes per annum and is planning a 20% expansion (Aracruz 1991; World Resources Institute 1998). It supplies 22% of the world’s bleached eucalypt pulp and 3% of the world’s total demand for pulp (Campinhos 1999). In 1995, Aracruz Celulose S.A. had a total revenue of US$796 million and is a major contributor to Brazil’s domestic economy. At the same time it contributes health care, housing, education and other benefits to the local communities in and around its plantations (World Resources Institute 1998).

However, the greater part of the eucalypt plantations in Brazil is used to provide high quality industrial charcoal for iron and steel production. Minas Gerais State, the centre of Brazil’s iron and steel industry, uses 70% of the wood from its eucalypt forests for production of industrial charcoal. There are several private companies in the State, each managing 150,000 to 200,000 hectares of eucalypt plantations. The main species used in charcoal plantations is E. grandis but C. citriodora, E. camaldulensis, E. cloeziana and E. paniculata are also significant. The latter species yield more charcoal per kilogram than E. grandis but are generally slower growing.

Forest managers have long recognised the potential to grow more wood per unit area through the application of tree breeding and more intensive management practices. In Brazil, the company Aracruz Celulose S.A. almost doubled yields from its plantations by species and provenance selection, breeding and the use of clones (Campinhos 1999); the company has 85% of its plantings from clonal cuttings (Bertolucci et al. 1995). Selected clones are also used