Transcript

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Fifth Edition

PLANT
PATHOLOGY
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Fifth Edition

PLANT
PATHOLOGY
GEORGE N. AGRIOS
Department of Plant Pathology
University of Florida

Amsterdam • Boston • Heidelberg • London • New York • Oxford
Paris • San Diego • San Francisco • Singapore • Sydney • Tokyo
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Publisher Dana Dreibelbis
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Library of Congress Cataloging-in-Publication Data

Agrios, George N., 1936–
Plant pathology / George Agrios. — 5th ed.
p. cm.
Includes bibliographical references and index.
ISBN 0-12-044565-4 (hardcover: alk. paper)
1. Plant diseases. I. Title.
SB731.A35 2004
571.9¢2 — dc22
2004011924

British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library

ISBN: 0-12-473276-3

For all information on all Elsevier Academic Press Publications
visit our Web site at www.books.elsevier.com

Printed in the United States of America
04 05 06 07 08 09 9 8 7 6 5 4 3 2 1
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This, the 5th and probably the last edition of Plant Pathology by me, is dedicated:

To the memory of my parents, Nikolas and Olga, who, in spite of their limited
education, sacrificed everything to give me the most and best education possible.

To the memory of Dr. Walter F. Buchholtz, my major professor at Iowa State
University, who challenged me before I had even taught my first lecture to “write
my own textbook on Plant Pathology”.

To my sisters, Dimitra and Evangelia, who have been there for me forever and who
also sacrificed some of their interests for my benefit.

To my wife, Annette, whose love and support have been the most precious things to
me throughout our life together, and who helped me in many facets of preparation of
this and of previous editions of Plant Pathology.

To my daughters-in-law, Betsy and Vivynne, who, by joining our family, added beauty,
love, enjoyment, and four wonderful grandchildren.

Finally, to Mark and Maximos, our youngest grandchildren, who, someday, when
they read their names in the book, may be reassured of “Granpa’s” love for them,
and may feel proud of their grandfather.
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Contents

Preface xix The Expanding Role of Fungi as Causes of Plant
Photo credits xxi Disease 21
About the Author xxiii The Discovery of the Other Causes of Infectious
Diseases 23
Nematodes — Protozoan Myxomycetes — Bacteria —
part one Viruses. Protozoa — Mollicutes — Viroids — Serious
Plant Diseases of Unknown Etiology 23
GENERAL ASPECTS Koch’s Postulates 26
Viruses, Viroids, and Prions 27
Losses Caused by Plant Diseases 29
chapter one Plant diseases reduce the quantity and quality of
plant produce. 29
INTRODUCTION White, Downey, and Dry Vineyards — Bring on the
Prologue: The Issues 4 Bordeaux! 30

Plants and Disease 4 Plant diseases may limit the kinds of plants and
The Concept of Disease in Plants 5 industries in an area. 32
Chestnuts, Elms, and Coconut Palm Trees — Where have
Types of Plant Diseases 7
they gone? 32
History of Plant Pathology and Early
Plant diseases may make plants poisonous to
Significant Plant Diseases 8
humans and animals 37
Introduction 8 Ergot, Ergotism, and LSD: a Bad Combination 37
Plant Diseases as the Wrath of Gods — Theophrastus 9 Mycotoxins and Mycotoxicoses 39
Mistletoe Recognized as the First Plant Pathogen 14
Plant diseases may cause financial losses. 41
Plant Diseases as the Result of Spontaneous
The Insect — Pathogen Connection: Multifaceted and
Generation 16
Important 42
Biology and Plant Pathology in Early Renaissance 16
Potato Blight — Deadly Mix of Ignorance and Plant Pathology in the 20th Century 45
Politics 19 Early Developments 45

vii
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viii CONTENTS

The Descriptive Phase 45 Identification of a Preciously Unknown Disease:
The Experimental Phase 46 Koch’s Postulates 74
The Etiological Phase 46
The Search for Control of Plant Diseases 46
The Main Areas of Progress 47
Chemical Control of Plant Diseases 47
chapter two
Appearance of Pathogen Races Resistant to Bactericides PARASITISM AND DISEASE
and Fungicides 48
Public Concern about Chemical Pesticides 48
DEVELOPMENT
Alternative Controls for Plant Diseases 49 Parasitism and Pathogenicity 77
Interest in the Mechanisms by Which Pathogens Cause Host Range of Pathogens 78
Disease 50
The Concept of Genetic Inheritance of Resistance and
Development of Disease in Plants 79
Pathogenicity 52 Stages in the Development of Disease:
Epidemiology of Plant Disease Comes of Age 53 The Disease Cycle 80
Plant Pathology Today and Future Inoculation 80
Directions 54 Inoculation, Types of Inoculum, Sources of Inoculum,
Landing or Arrival of Inoculum 80
Molecular Plant Pathology 54
Prepenetration Phenomena 82
Aspects of Applied Plant Pathology 56
Attachment of Pathogen to Host, Spore Germination and
Plant Biotechnology — The Promise and the
Perception of the Host Surface, Appressorium
Objections 56
Formation and Maturation, Recognition between Host
Food Safety 58
and Pathogen, Germination of Spores and Seeds,
Bioterrorism, Agroterrorism, Biological Warfare, etc. Who,
Hatching of Nematode Eggs 82
What, Why 59
Penetration 87
Worldwide Development of Plant Pathology as
Direct Penetration through Intact Plant Surfaces,
a Profession 60 Penetration through Wounds, Penetration through
International Centers for Agricultural Research 60 Natural Openings 87
Trends in Teaching and Training 61
Infection 89
Plant Disease Clinics 62
Infection, Invasion, Growth and Reproduction of the
The Practice and Practitioners of Plant Pathology 63
Pathogen (Colonization) 89
Certification of Professional Plant Pathologists 63
Plant Pathology as a Part of Plant Medicine; the Doctor of Dissemination of the Pathogen 96
Plant Medicine Program 64 Dissemination by Air, Dissemination by Water,
Dissemination by Insects, Mites, Nematodes, and Other
Plant Pathologists’ Contributin to Crops
Vectors, Dissemination by Pollen, Seed, Transplants,
and Society 65 Budwood, and Nursery Stock, Dissemination by
Some Historical and Present Examples of Losses Humans 96
Caused by Plant Diseases 65 Overwintering and/or Oversummering of
Plant Diseases and World Crop Production 65 Pathogens 100
Crop Losses to Diseases, Insects and Relationships between Disease Cycles and
Weeds 66 Epidemics 102
Pesticides and Plant Diseases 69
Basic Procedures in the Diagnosis of Plant
Diseases 71 chapter three
Pathogen or Environment 71 EFFECTS OF PATHOGENS ON PLANT
Infectious Diseases 72 PHYSIOLOGICAL FUNCTIONS
Parasitic Higher Plants — Nematodes — Fungi and
Bacteria: Fungi — Bacteria and Mollicutes 72 Effects of Pathogens on Photosynthesis 106
Viruses and Viroids — More than One Pathogen 73 Effect of Pathogens on Translocation of Water
Noninfectious Diseases 73 and Nutrients in the Host Plant 106
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CONTENTS ix

Interference with Upward Translocation of Water Genetics of Virulence in Pathogens and of
and Inorganic Nutrients 106 Resistance in Host Plants 139
Effect on Absorption of Water by Roots 108 The Nature of Resistance to Disease —
Effect on Translocation of Water through Pathogenicity Genes in Plant Pathogens 142
the Xylem 108 Genes Involved in Pathogenesis and Virulence by
Pathogens 142
Effect on Transpiration 108
Interference with the Translocation of Organic Pathogenicity Genes of Fungi controlling:
Nutrients through the Phloem 113 Production of Infection Structures — Degradation
Effect of Pathogens on Host Plant of Cuticle and Cell Wall — Secondary Metabolites
Respiration 115 — Fungal Toxins — Pathogenicity Signaling
Respiration of Diseased Plants 117 Systems 144
Effect of Pathogens on Permeability of Cell Pathogenicity Genes in Plant Pathogenic Bacteria
Membranes 118 controlling: Adhesion to Plant Surfaces —
Effects of Pathogens on Transcription and Secretion Systems — Enzymes that Degrade Cell
Translation 118 Walls — Bacterial Toxins as Pathogenicity Factors
Effect on Transcription 119 — Extracellular Polysaccharides as Pathogenicity
Effect on Translation 119 Factors — Bacterial Regulatory Systems and
Effect of Pathogens on Plant Growth 119 Networks — Sensing Plant Signaling
Effect of Pathogens on Plant Components — Other Bacterial Pathogenicity
Reproduction 121 Factors 146
Pathogenicity Genes in Plant Viruses: — Functions
Associated with the Coat Protein — Viral
Pathogenicity Genes 149
chapter four
Nematode Pathogenicity Genes 150
GENETICS OF PLANT DISEASE Genetics of Resistance through the Hypersensitive
Introduction 125 Response 151
Genes and Disease — Variability in Organisms — Pathogen-Derived Elicitors of Defense Responses in
Plants 151
Mechanisms of Variability 126
Avirulence (avr) Genes: One of the Elicitors of Plant
General Mechanisms: Mutation — Recombination —
Defense Responses Characteristics of avr Gene-Coded
Gene and Genotype Flow among Plant Pathogens —
Proteins: — Their Structure and Function Role of avr
Population Genetics, Genetic Drift, and Selection —
Genes in Pathogenicity and Virulence 154
Life Cycles — Reproduction — Mating Systems —
hrp Genes and the Type III Secretion System 155
Out-crossing — Pathogen Fitness 129
Specialized Mechanisms of Variability in Pathogens: Resistance (R) Genes of Plants: Examples of R
Sexual-like Processes in Fungi Heterokaryosis — Genes — How Do R Genes Confer Resistance? –
Parasexualism — Vegetative Incompatibility — Evolution of R Genes — Other Plant Genes for
Heteroploidy 131
Resistance to Disease 155
Sexual-like Processes in Bacteria and Horizontal Gene
Transfer 132 Signal Transduction between Pathogenicity Genes
Genetic Recombination in Viruses 133 and Resistance Genes: — Signaling and
Loss of Pathogen Virulence in Culture 133 Regulation of Programmed Cell Death — Genes
Stages of Variation in Pathogens 134 and Signaling in Systemic Acquired
Types of Plant Resistance to Pathogens 134 Resistance 160
True Resistance: Partial, Quantitative, Polygenic, or
Examples of Molecular Genetics of Selected Plant
Horizontal Resistance — R-Gene Resistance,
Monogenic, or Vertical Resistance 136 Diseases: — The Powdery Mildew Disease —
Disease Escape — Tolerance to Disease 137 Magnaporthe grisea, the Cause of Rice Blast —
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x CONTENTS

Fusarium, the Soilborne Plant Pathogen — Role of Type III Secretion in Bacterial Pathogenesis
Ustilago maydis and Corn Smut 161 202
Breeding of Resistant Varieties 165 Pathogenicity and Virulence Factors in Viruses and
Natural Variability in Plants — Breeding and Viroids 202
Variability in Plants — Breeding for Disease
Resistance Sources of Genes for Resistance —
Techniques Used in Classical Breeding for
Resistance — Seed, Pedigree, and Recurrent chapter six
Selection — Tissue Culture and Genetic HOW PLANTS DEFEND THEMSELVES
Engineering Techniques 165 AGAINST PATHOGENS
Genetic Transformation of Plant Cells for Disease
Whatever the Plant Defense or Resistance, It Is
Resistance 169
Controlled by Its Genes 208
Advantages and Problems in Breeding for Vertical
Non-host Resistance — Partial, Polygenic,
or Horizontal Resistance 169
Quantitative, or Horizontal Resistance —
Vulnerability of Genetically Uniform Crops to Plant
Monogenic, R Gene, or Vertical
Disease Epidemics 170
Resistance 208
Preexisting Structural and Chemical
Defenses 210
chapter five Preexisting Defense Structures 210
HOW PATHOGENS ATTACK PLANTS Preexisting Chemical Defenses 211
Inhibitors Released by the Plant in Its Environment —
Mechanical Forces Exerted By Pathogens on
Inhibitors Present in Plant Cells before Infection 211
Host Tissues 177
Defense through Lack of Essential
Chemical Weapons of Pathogens 179
Factors 212
Enzymes in Plant Disease 180
Lack of Recognition between Host and Pathogen:
Enzymatic Degradation of Cell Wall Substances 180
Cuticular Wax — Cutin — Pectic Substances — Cellulose Lack of Host Receptors and Sensitive Sites for
— Cross-Linking Glycans (Hemicelluloses) — Suberin Toxins — Lack of Essential Substances for the
— Lignin — Cell Wall Flavonoids — Cell Wall Pathogen 212
Structural Proteins 180
Induced Structural and Biochemical
Enzymatic Degradation of Substances Contained in Plant
Cells 189 Defenses 213
Proteins — Starch — Lipids 189 Recognition of the Pathogen by the Host Plant 213
Transmission of the Alarm Signal to Host Defense
Microbial Toxins in Plant Disease 190
Providers: Signal Transduction 214
Toxins That Affect a Wide Range of Host Plants 190
Tabtoxin — Phaseolotoxin — Tentoxin — Cercosporin Induced Structural Defenses: Cytoplasmic
— Other Non-Host-Specific Toxins 191 Defense Reaction — Cell Wall Defense
Host-Specific or Host-Selective Toxins 193 Structures 214
Victorin, HV Toxin — T-Toxin [Cochliobolus
Histological Defense Structures: Formation of Cork
(Helminthosporium) heterostrophus Race T-Toxin] —
C-Toxin — Alternaria alternata Toxins — Other Layers — Abscission Layers — Tyloses —
Host-Specific Toxins 194 Deposition of Gums 215
Growth Regulators in Plant Disease 196 Necrotic Structural Defense Reaction:
Detoxification of Low-Molecular Weight Defense through the Hypersensitive
Antimicrobial Molecules 201 Response 217
Promotion of Bacterial Virulence By avr Induced Biochemical Defenses in: Non-Host
Genes 202 Resistance — In Partial, Quantitative
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(Polygenic, General, or Horizontal) Treatment with Chemicals 237
Resistance: Function of Gene Products in Defense through Genetically Engineering
Quantitative Resistance — The Mechanisms Disease-Resistant Plants 242
of Quantitative Resistance — Effect With Plant-Derived Genes — With
of Temperature on Quantitative Pathogen-Derived Genes 242
Resistance 217 Defense through RNA Silencing by
Induced Biochemical Defenses in the Pathogen-Derived Genes 242
Hypersensitive Response (R Gene)
Resistance 221
The Hypersensitive Response: Genes Induced
chapter seven
During Early Infection — Functional Analysis of
Plant Defense Genes — Classes of R Gene ENVIRONMENTAL EFFECTS ON THE
Proteins — Recognition of Avr Proteins of DEVELOPMENT OF INFECTIOUS
Pathogens by the Host Plant — How Do R and PLANT DISEASE
Avr Gene Products Activate Plant Responses? — Introduction 251
Some Examples of Plant Defense through R Effect of Temperature 253
Genes and Their Matching Avr Genes: — The Effect of Moisture 257
Rice Pi-ta Gene. The Tomato Cf Genes. The Effect of Wind 257
Tomato Bs2 Gene. The Arabidopsis RPM1 Effect of Light 257
Gene — The Co-function of Two or More Effect of Soil pH and Soil Structure 257
Genes. 221 Effect of Host-Plant Nutrition 257
Defense Involving Bacterial Type III Effector Effect of Herbicides 262
Proteins 229 Effect of Air Pollutants 262
Production of Active Oxygen Species,
Lipoxygenases, and Disruption of Cell
Membranes — Reinforcement of Host Cell Walls
chapter eight
with Strengthening Molecules 231
Production of Antimicrobial Substances in Attacked PLANT DISEASE EPIDEMIOLOGY
Host Cells — Pathogenesis-Related (PR) The Elements of an Epidemic 266
Proteins 232 Host Factors That Affect the Development of
Defense through Production of Secondary Epidemics 267
Metabolites — Phenolics: — Simple Phenolic Levels of Genetic Resistance or Susceptibility of the
Compounds — Toxic Phenolics from Nontoxic Host — Degree of Genetic Uniformity of Host
Phenolic Glycosides — Role of Phenol-Oxidizing Plants — Type of Crop — Age of Host
Enzymes in Disease Resistance — Plants 267
Phytoalexins 233 Pathogen Factors That Affect Development of
Detoxification of Pathogen Toxins by Plants — Epidemics 269
Immunization of Plants against Pathogens: Levels of Virulence — Quantity of Inoculum Near
Defense through Plantibodies 236 Hosts — Type of Reproduction of the Pathogen
Resistance through prior Exposure to Mutants of — Ecology of the Pathogen — Mode of Spread of
Reduced Pathogenicity 237 the Pathogen 269
Systemic Acquired Resistance: — Induction by Environmental Factors That Affect
Artificial Inoculation with Microbes or by Development of Epidemics 271
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Moisture — Temperature 271 Coatings 295
Effect of Human Cultural Practices and Control Methods that Eradicate or Reduce
Control Measures 272 Pathogen Inoculum 298
Site Selection and Preparation — Selection of Cultural Methods that Eradicate or Reduce the
Propagative Material — Cultural Practices — Inoculum: — Host Eradication — Crop Rotation
Disease Control Measures — Introduction of New — Sanitation — Creating Conditions Unfavorable
Pathogens 272 to the Pathogen — Polyethylene Traps and
Measurement of Plant Disease and of Yield Mulches 300
Loss 273 Biological Methods that Eradicate or Reduce the
Patterns of Epidemics — Comparison of Inoculum: — Suppressive Soils 303
Epidemics — Development of Epidemics — Reducing Amount of Pathogen Inoculum through
Modeling of Plant Disease Epidemics — Antagonistic Microorganisms Soilborne Pathogens
Computer Simulation of Epidemics 274 — Aerial Pathogens — Mechanisms of Action —
Forecasting Plant Disease Epidemics 281 Control through Trap Plants — Control through
Evaluation of Epidemic Thresholds — Evaluation of Antagonistic Plants 305
Economic Damage Threshold — Assessment of Physical Methods that Eradicate or Reduce the
Initial Inoculum and of Disease — Monitoring Inoculum — Control by Heat Treatment — Soil
Weather Factors That Affect Disease Sterilization by Heat — Soil Solarization Hot-
Development 281 Water Treatment of Propagative Organs — Hot-
New Tools in Epidemiology 283 Air Treatment of Storage Organs Control by
Molecular Tools. GIS. Remote Sensing. Image Eliminating Certain Light Wavelengths — Drying
Analysis. Information Technology 283 Stored Grains and Fruit — Disease Control
Examples of Plant Disease Forecast by Radiation — Trench Barriers against
Systems 285 Root-transmitted Tree Diseases 310
Forecasts Based on Amount of Initial Inoculum — Chemical Methods that Eradicate or Reduce the
On Weather Conditions Favoring Development of Inoculum — Soil Treatment with Chemicals —
Secondary Inoculum — On Amounts of Initial Fumigation — Disinfestation of Warehouses —
and Secondary Inoculum 285 Control of Insect Vectors 312
Disease-Warning Systems — Development and Cross Protection — Induced Resistance: Systemic
Use of Expert Systems in Plant Pathology — Acquired Resistance — Plant Defense Activators
Decision Support Systems 289 — Improving the Growing Conditions of Plants
— Use of Resistant Varieties 314
Control through Use of Transgenic Plants
chapter nine
Transformed for Disease Resistance Transgenic
CONTROL OF PLANT DISEASES Plants that Tolerate Abiotic Stresses — Transgenic
Control Methods that Exclude the Pathogen Plants Transformed with: Specific Plant Genes for
from the Host 295 Resistance — with Genes Coding for Anti-
Quarantines and Inspections — Crop Certification pathogen Compounds — with Nucleic Acids that
— Evasion or Avoidance of Pathogen — Use of Lead to Resistance and to Pathogen Gene
Pathogen-Free Propagating Material — Pathogen- Silencing — with Combinations of Resistance
Free Seed — Pathogen-Free Vegetative Genes — Producing Antibodies against the
Propagating Materials — Exclusion of Pathogen — Transgenic Biocontrol
Pathogens from Plant Surfaces by Epidermal Microorganisms 319
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CONTENTS xiii

Direct Protection of Plants from part two
Pathogens 322
By Biological Controls: — Fungal Antagonists:
Heterobasidion (Fomes) annosum by Phleviopsis SPECIFIC PLANT DISEASES
(Peniophora) gigantea — Chestnut Blight with
Hypovirulent Strains of the Pathogen — Soilborne chapter ten
Diseases — Diseases of Aerial Plant Parts with
ENVIRONMENTAL FACTORS THAT
Fungi. — Postharvest Diseases Bacterial
CAUSE PLANT DISEASES
Antagonists: Soilborne Diseases — Diseases of
Introduction: General Characteristics —
Aerial Plant Parts with Bacteria — Postharvest
Diagnosis — Control 358
Diseases — with Bacteria of Bacteria-Mediated
Temperature Effects: High-Temperature Effects
Frost Injury 328
— Low-Temperature Effects —
Viral Parasites of Plant Pathogens 328
Low- Temperature Effects on Indoor
Biological Control of Weeds 328
Plants 358
Direct Protection by Chemicals 329
Moisture Effects: Low Soil Moisture Effects —
Methods of Application of Chemicals for Plant
Low Relative Humidity — High Soil
Disease Control — Foliage Sprays and Dusts —
Moisture Effects 365
Seed Treatment — Soil Treatment — Treatment
Inadequate Oxygen 367
of Tree Wounds — Control of Postharvest
Light 368
Diseases 332
Air Pollution 368
Types of Chemicals Used for Plant Disease
Air Pollutants and Kinds of Injury to Plants —
Control 338
Inorganic — Inorganic Sulfur Compounds — Carbonate Main Sources of Air Pollutants — How Air
Compounds — Phosphate and Phosphonate Compounds Pollutants Affect Plants — Acid Rain 000
— Film-Forming Compounds 338 Nutritional Deficiencies in Plants 372
Organic Chemicals: Contact Protective Fungicides —
Soil Minerals Toxic to Plants 372
Organic Sulfur Compounds: Ditihiocarbamates 339
Systemic Fungicides: — Heterocyclic Compounds — Herbicide Injury 378
Acylalanines — Benzimidazoles — Oxanthiins — Other Improper Agricultural Practices 381
Organophosphate Fungicides — Pyrimidines — The Often Confused Etiology of Stress
Trizoles — Strobilurins or QoI Fungicides —
Diseases 383
Miscellaneous Systemics 340
Miscellaneous Organic Fungicides — Antibiotics —
Petroleum Oils and Plant Oils — Electrolyed Oxidizing
Water — Growth Regulators — Nematicides: — chapter eleven
Hologenated Hydrocarbons — Organophosphate
PLANT DISEASES CAUSED BY FUNGI
Nematicides — Isothiocoyanates — Carbamates —
Miscellaneous Nematicides 343 Introduction 383
Mechanisms of Action of Chemicals Used to Some Interesting Facts about
Control Plant Diseases — Resistance of Pathogens Fungi (Box) 387
to Chemicals — Restrictions on Chemical Control Characteristics of plant pathogenic
of Plant Diseases 345 fungi 388
Integrated Control of Plant Diseases: — In a Morphology — Reproduction — Ecology —
Perennial Crop — In an Annual Crop 348 Dissemination 388
Classification of Plant Pathogenic
Fungi 390
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Fungallike Organisms — The True Fungi 391 Cochliobolus Diseases of Wheat, Barley, and Other
Identification: Symptoms Caused by Fungi on Grasses 469
Crown Rot and Common Root Rot — Spot Blotch of
Plants 397 Barley and Wheat 469
Isolation of fungi (and Bacteria) 398 Pyrenophora Diseases of Wheat, Barley and Oats 469
Preparing for Isolation — Isolating the Net Blotch of Barley — Barley Stripe — Tan Spot of
Pathogen 398 Wheat 469

Life Cycles of Fungi 402 Stem and Twig Cankers Caused by
Control of Fungal Diseases of Plants 403 Ascomycetes and Deuteromycetes
Diseases Caused by Fungallike (Mitosporic Fungi) 473
Organisms 404 Black Knot of Plum and Cherry — Chestnut Blight
Diseases Caused by Myxomycota — Nectria Canker — Leucostoma Canker 476
(Myxomycetes) 404 Cankers of Forest Trees: — Hypoxylon Canker —
Diseases Caused by Pitch Canker — Butternut Canker — Phomopsis
Plasmodiophoromycetes 405 Blight — Seiridium Canker 481
Clubroot of Crucifers 407 Anthracnose Diseases Caused by Ascomycetes
Diseases Caused by Oomycetes 409 and Deureromycetes (Mitosporic
Pythium Seed Rot, Damping-off, Root Rot, and Fungi) 483
Soft Rot 410 Black Spot of Rose 485
Phytophthora Diseases 414 Elsinoe Anthracnose and Scab Diseases: — Grape
Phytophthora Root and Stem Rots — Phytophthoras Anthracnose or Bird’s-eye Rot — Raspberry
Declare War on Cultivated Plants and on Native Tree Anthracnose — Citrus Scab Diseases — Avocado
Species (Box) 414
Scab 486
Late Blight of Potatoes 421 Colletotrichum Diseases: Colletotrichum
The Downy Mildews 427 Anthracnose Diseases of Annual Plants 487
Introduction — Downy Mildew of Grape 428
Anthracnose of Beans — Anthracnose of Cucurbits —
Diseases Caused by True Fungi 433 Anthracnose or Ripe Rot of Tomato — Onion
Diseases Caused by Chytridiomycetes 433 Anthracnose or Smudge — Strawberry Anthracnose —
Diseases Caused by Zygomycetes 434 Anthracnose of Cereals and Grasses 490

Diseases Caused by Ascomycetes and Colletotrichum Anthracnoses: A Menace To
Mitosporic Fungi 439 Tropical Crops (Box) Colletotrichum 491
Bitter Rot of Apple — Ripe Rot of Grape 494
Sooty molds — Taphrina leaf Curl Diseases —
Gnomonia Anthracnose and Leaf Spot
Powdery Mildews 440
Diseases 498
Foliar Diseases Caused by Ascomycetes and
Dogwood Anthracnose 501
Deuteromycetes (Mitosporic Fungi) 452
Fruit and General Diseases Caused by
Alternaria Diseases — Cladosporium Diseases —
Ascomycetes and Deuteromycetes
Needle Casts and Blights of Conifers 452
Mycosphaerella Diseases: Banana Leaf Spot or Sigatoka (Mitosporic Fungi) 501
Disease 458 Ergot of Cereals and Grasses — Apple Scab —
Septoria Diseases — Cercospora Diseases — Rice Blast Brown Rot of Stone Fruits — Monoliophthora
Disease 460
Pod Rot of Cacao — Botrytis Diseases — Black
Cochliobolus, Pyrenophora and Setosphaeria Diseases of
Cereals and Grasses 466 Rot of Grape — Cucurbit Gummy Stem Blight
Diseases of Corn: — Southern Corn Leaf Blight — and Black Rot — Diaporthe, Phomopsis, and
Northern Corn Leaf Blight — Northern Corn Leaf Phoma Diseases — Stem Canker of Soybeans —
Spot 466
Melanose Disease of Citrus — Phomopsis
Diseases of Rice — Brown Spot Disease of Rice 468
Diseases — Black Rot of Apple 501
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Vascular Wilts Caused by Ascomycetes The Rusts 562
and Deuteromycetes (Mitosporic Cereal Rusts — Stem Rust of Wheat and Other
Fungi) 522 Cereals 565
Fusarium Wilts: Of Tomato — Fusarium or Panama Rusts of Legumes — Bean Rust — Soybean Rust —
Wilt of Banana 523 A Major Threat to a Major Crop (Box) 571
Verticillium Wilts 526 Cedar-Apple Rust — Coffee Rust 574
Ophiostoma Wilt of Elm Trees: Dutch Elm Rusts of Forest Trees: — White Pine Blister Rust —
Disease 528 Fusiform Rust 577
Ceratocystis Wilts — Oak wilt — Ceratocystis Wilt The Smuts 582
of Eucalyptus 532 Corn Smut — Loose Smut of Cereals — Covered
Root and Stem Rots Caused by Ascomycetes Smut, or Bunt, of Wheat 588
and Deuteromycetes (Mitosporic Karnal Bunt of Small Grains–Legitimate Concerns
Fungi) 534 and Political Predicaments (Box) 592
Gibberella Diseases — Gibberella Stalk and Ear Root and Stem Rots Caused by
Rot, and Seedling Blight of Corn 535 Basidiomycetes 593
Fusarium (Gibberella) Head Blight (FHB) or Scab Root and Stem Rot Diseases Caused by the “Sterile
of Small Grains 535 Fungi” Rhizoctonia and Sclerotium 593
Fusarium Root and Stem Rots of Non-Grain Rhizoctonia Diseases — Sclerotium Diseases 594

Crops 538 Root Rots of Trees 602
Armillaria Root Rot of Fruit and Forest Trees 602
Take-All of Wheat — Thielavopsis Black Root Rot
Wood Rots and Decays Caused by
— Monosporascus Root Rot and Vine Decline of
Basidiomycetes 604
Melons 540
Witches’ Broom of Cacao 611
Sclerotinia Diseases: Sclerotinia Diseases of
Vegetables and Flowers — Phymatotrichum Root
Rot 546
Postharvest Diseases of Plant Products Caused chapter twelve
by Ascomycetes and Deuteromycetes 553
PLANT DISEASES CAUSED BY
Postharvest Decays of Fruits and Vegetables 556
Aspergillus, Penicillium, Rhizopus, and Mucor —
PROKARYOTES: BACTERIA AND
Alternaria — Botrytis — Fusarium — Geotrichum — MOLLICUTES
Penicillium — Sclerotinia 556 Introduction 616
Control of Postharvest Decays of Fresh Fruits and Plant Diseases Caused by Bacteria 618
Vegetables 557 Characteristics of Plant Pathogenic Bacteria 618
Postharvest Decays of Grain and Legume Morphology — Reproduction — Ecology and
Seeds 558 Spread — Identification of Bacteria — Symptoms
Caused by Bacteria — Control of Bacterial Diseases
Mycotoxins and Mycotoxicoses 559
of Plants 618
Aspergillus Toxins — Aflatoxins 559
Fusarium Toxins — Other Aspergillus Toxins and Bacterial Spots and Blights 627
Penicillium Toxins 559 Introduction — Wildfire of Tobacco — Bacterial
Control of Postharvest Grain Decays 560 Blights of Bean — Angular Leaf Spot of
Diseases Caused by Basidiomycetes 562 Cucumber — Angular Leaf Spot or Bacterial
The Rusts — The Smuts — Root and Stem Blight of Cotton — Bacterial Leaf Spots and
Rots — Wood Rots and Decays — Witches’ Blights of Cereals and Grasses — Bacterial Spot
Broom 562 of Tomato and Pepper — Bacterial Speck of
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xvi CONTENTS

Tomato — Bacterial Fruit Blotch of Watermelon (Phloem Necrosis) — Peach X-Disease — Pear
— Cassava Bacterial Blight — Bacterial Spot of Decline 691
Stone Fruits 627 Spiroplasma Diseases 699
Bacterial Vascular Wilts 638 Citrus Stubborn Disease — Corn Stunt
Bacterial Wilt of Cucurbits — Fire Blight of Pear Disease 691
and Apple — Southern Bacterial Wilt of
Solanaceous Plants — Bacterial Wilt or Moko chapter thirteen
Disease of Banana — Ring Rot of Potato 639 PLANT DISEASES CAUSED BY
Bacterial Canker and Wilt of Tomato — Bacterial PARASITIC HIGHER PLANTS, INVASIVE
Wilt (Black Rot) of Crucifers — Stewart’s Wilt of CLIMBING PLANTS, AND PARASITIC
Corn 651 GREEN ALGAE
Bacterial Soft Rots 656
Introduction — Parasitic Higher Plants 705
Bacterial Soft Rots of Vegetables 656
Dodder –Witchweed — Broomrapes — Dwarf
The Incalculable Postharvest Losses from Bacterial
Mistletoes of Conifers — True or Leafy
(and Fungal) Soft Rots (Box) 660
Mistletoes 706
Bacterial Galls 662
Invasive Climbing Plants 716
Crown Gall 662
Old World Climbing Fern — Kudzu Vine 717
The Crown Gall Bacterium — The Natural Genetic
Parasitic Green Algae: Cephaleuros 719
Engineer (Box) 664
Plant Diseases Caused by Algae 719
Bacterial Cankers 667
Bacterial Canker and Gummosis of Stone Fruit
chapter fourteen
Trees — Citrus Canker 667
Bacterial Scabs 674 PLANT DISEASES CAUSED BY VIRUSES
Common Scab of Potato 667 Introduction 724
Root Nodules of Legumes 675 Characteristics of Plant Viruses 724
Xylem-Inhabiting Fastidious Bacteria 678 Detection — Morphology — Composition and
Pierce’s Disease of Grape — Citrus Structure: Of Viral Protein — Of Viral Nucleic
Variegated Chlorosis — Ratoon Stunting of Acid 725
Sugarcane 679 Satellite Viruses and Satellite RNAs 731
Phloem-Inhabiting Fastidious Bacteria 683 The Biological Function of Viral Components:
Yellow Vine Disease of Cucurbits — Citrus Coding 731
Greening Disease — Papaya Bunchy Top Virus Infection and Virus Synthesis 731
Disease 684 Translocation and Distribution of Viruses in
Plant Diseases Caused By Mollicutes: Plants 733
Phytoplasmas and Spiroplasmas 687 Symptoms Caused by Plant Viruses 734
Properties of True Mycoplasmas — Phytoplasmas — Physiology of Virus-Infected Plants 737
Spiroplasmas 688 Transmission of Plant Viruses By: Vegetative
Examples of Plant Diseases Caused by Propagation — Sap — Seed — Pollen —
Mollicutes 691 Insects — Mites — Nematodes — Fungi —
Aster Yellows — Lethal Yellowing of Coconut Dodder 737
Palms — Apple Proliferation — European Stone Epidemiology of Plant Viruses and
Fruit Yellows — Ash Yellows — Elm Yellows Viroids 743
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CONTENTS xvii

Purification of Plant Viruses — Serology of Tombusviridae 779
Plant Viruses 743 Diseases Caused by Luteoviridae 781
Nomenclature and Classification of Plant Barley Yellow Dwarf — Potato Leafroll — Beet
Viruses 747 Western Yellows 781
Detection and Identification of Plant Diseases Caused by Monopartite Isometric
Viruses 751 (+)ssRNA Viruses of Genera Not Yet
Economic Importance of Plant Viruses 752 Assigned to Families 783
Control of Plant Viruses 753 Diseases Caused by Comoviridae 784
Diseases Caused by Rigid Rod-Shaped Diseases Caused by Comoviruses 784
Viruses 757 Diseases Caused by Nepoviruses 784
Diseases Caused by Tobamoviruses: — Tobacco Tomato Ring Spot — Grapevine Fanleaf — Raspberry Ring
Spot 785
Mosaic 757
Diseases Caused by Bromoviridae 787
The Contribution of Tobacco Mosaic Virus to
Diseases Caused by Cucumoviruses 787
Biology and Medicine (Box) 757
Cucumber Mosaic 788
Diseases Caused by Tobraviruses: — Tobacco Rattle
Diseases Caused by Ilarviruses: Prunus Necrotic
by Furoviruses — by Hordeiviruses — by
Ring Spot 790
Pecluviruses — by Pomoviruses — by
Diseases Caused by Isometric Double-Stranded
Benyviruses 758
RNA Viruses 792
Diseases Caused by Filamentous Viruses
Diseases Caused by Reoviridae 792
762
Diseases Caused by Negative RNA [(-)ssRNA]
Diseases Caused by Potexviruses — by Carlaviruses
Viruses 794
— by Capilloviruses and Trichoviruses — by
Plant Diseases Caused by Rhabdoviruses
Allexiviruses, Foveaviruses, and
794
Vitiviruses 762
Plant Diseases Caused by Tospoviruses 795
Diseases Caused by Potyviridae 764
Plant Diseases Caused by Tenuiviruses 799
Diseases Caused by Potyviruses 764
Bean Common Mosaic and Bean Yellow Mosaic — Lettuce Diseases Caused by Double-Stranded DNA
Mosaic — Plum Pox — Papaya Ringspot — Potato Virus Viruses 801
Y — Sugarcane Mosaic — Tobacco Etch — Turnip Diseases Caused by Caulimoviruses and Other
Mosaic — Watermelon Mosaic — Zucchini Yellow
Isometric Caulimoviridae 801
Mosaic 767
Diseases Caused by Badnaviruses 803
Diseases Caused by Ipomoviruses, Macluraviruses,
Diseases Caused by Single-Stranded DNA
Rymoviruses, and Tritimoviruses — by
Viruses 805
Bymoviruses 773
Plant Diseases Caused by
Diseases Caused by Closteroviridae 774
Geminiviridae 805
Diseases Caused by Closteroviruses: — Citrus
Beet Curly Top — Maize Streak — African Cassava
Tristeza — Beet YellowsDiseases Caused by
Mosaic — Bean Golden Mosaic — Squash Leaf
Criniviruses: — Lettuce Infectious Yellows 774
Curl — Tomato Mottle — Tomato Yellow Leaf
Diseases Caused by Isometric Single-Stranded
Curl 809
RNA Viruses 779
Plant Diseases Caused by Isometric Single-
Diseases Caused by Sequiviridae, Genus
Stranded 813
Waikavirus 779
DNA Viruses: The Circoviridae 813
Rice TungroDiseases Caused by
Banana Bunchy Top 814
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xviii CONTENTS

Coconut Foliar Decay 815 Lesion Nematodes: Pratylenchus 849
Viroids 816 The Burrowing Nematode: Radopholus 853
Plant Diseases Caused by Viroids 816 The Added Significance of Plant Nematodes in
Taxonomy (Grouping) of Viroids 816 the Tropics and Subtropics (Box) 858
Potato Spindle Tuber — Citrus Exocortis — Coconut
Stem and Bulb Nematode: Ditylenchus 858
Cadang-Cadang 820
Sting Nematode: Belonolaimus 860
Stubby-Root Nematodes: Paratrichodorus and
Trichodorus 863
chapter fifteen Seed-Gall Nematodes: Anguina 865
Foliar Nematodes: Aphelenchoides 867
PLANT DISEASES CAUSED BY
Pine Wilt and Palm Red Ring Diseases:
NEMATODES
Bursaphelenchus 870
Introduction 826 Pine Wilt Nematode: Bursaphelenchus
Characteristics of Plant Pathogenic xylophilus 870
Nematodes 827 Red Ring Nematode: Bursaphelenchus
Morphology — Anatomy — Life Cycles — Ecology
cocophilus 872
and Spread — Classification 827
Isolation of Nematodes 831
Isolation of Nematodes from Soil 831
chapter sixteen
Isolation of Nematodes from Plant Material
832 PLANT DISEASES CAUSED BY
Symptoms Caused by Nematodes 832 FLAGELLATE PROTOZOA
How Nematodes Affect Plants 833 Introduction 875
Interrelationships between Nematodes and Nomenclature of Plant Trypanosomatids —
Other Plant Pathogens 835 Taxonomy — Pathogenicity — Epidemiology and
Control of Nematodes 836 Control of Plant Trypanosomatids 877
Important Nematodes and Diseases 838 Plant Diseases Caused by: 878
Root-Knot Nematodes: Meloidogyne 838 Phloem-Restricted Trypanosomatids 878
Cyst Nematodes: Heterodera and Phloem Necrosis of Coffee — Hartrot of Coconut Palms —
Sudden Wilt (Marchitez Sopresiva) of Oil Palm — Wilt
Globodera 842 and Decay of Red Ginger 878
Soybean Cyst Nematode: Heterodera
Laticifer-Restricted trypanosomatids 882
glycines 843 Empty Root of Cassava 882
Sugar Beet Nematode: Heterodera schachtii 846 Fruit-and Seed-Infecting Trypanosomatids 882
Potato Cyst Nematode: Globodera rostochiensis Fruit Trypanosomatids 882
and Globodera pallida 847
The Citrus Nematode: Tylenchulus Glossary 887
Semipenetrans 848 Index 903
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Preface

ince the appearance of the 1st edition of Plant opments in each area and gives the instructor choices in

S Pathology in June 1969, tremendous advances have
been made both in the science of plant pathology
and in the publishing business. New information pub-
the type and amount of general concepts material
(Chapters 1–9) and of specific diseases (Chapters 10–16)
he/she will cover. Each chapter begins with a fairly
lished in the monthly plant pathological and related detailed, well-organized table of contents that can be
biological journals, as well as in specialized books and used by students and instructors as an outline for the
annual reviews, was digested and pertinent portions of chapter. The instructor can also use it to cover parts of
it were included in each new edition of the book. The it in detail in class while some of the topics are covered
worldwide use of the book, in English or in its several briefly and others are assigned to the students as further
translations, also created a need to describe additional reading. Each student, however, has all the latest mate-
diseases affecting crops important to different parts of rial, well organized and beautifully illustrated, available
the world. There has been, therefore, a continuous need in a way that is self-explanatory and, with the complete
to add at least some additional text and more illustra- glossary provided, can be understood with minimal
tions to the book with as little increase in the size of the effort.
book as possible. Fortunately, through the use of com- Instructors will have an even greater choice in the
puters, tremendous advances have been made in the kinds of specific diseases one would use in a specific area
publishing business, including paper quality and labor of the country or of the world where one teaches. While
costs and, particularly, in the reproducibility and afford- one may want to include the teaching of potato late
ability of color photographs and diagrams. Plant dis- blight, apple scab, wheat rust, bacterial soft rot, root
eases and plant pathology come alive when illustrated knot, and some other diseases of general interest, one
in full color and it has been the author’s dream to have often also wants to cover diseases of particular interest
all the figures in color. Add to these advances the inter- in the region, both because of their regional importance
est of the author and of the publishers to spare no effort and because of their availability locally for further study
or expense in the production of this book and you have in the classroom and the laboratory. This edition makes
what we believe is the best book possible for the effec- this possible by covering and illustrating in full color a
tive teaching of plant pathology at today’s college level wide variety of diseases, some of which are important
worldwide. to the grain plains of the Midwest and the northwest-
To begin with, “Plant Pathology, 5th edition” pro- ern United States, others to the fruit- and vegetable-
vides each instructor with all the significant new devel- producing Pacific and northeastern states, others to the

xix
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xx P R E FAC E

cotton-, peanut-, tobacco-, rice-, and citrus-vegetable genetics and its use in developing defenses in plants,
producing southern states, and so on. A special effort against pathogens. Discoveries in basic molecular genet-
has also been made to describe and to fully illustrate in ics, particularly discoveries in how plants defend them-
full color several diseases of tropical crops important in selves against pathogens and in the development of
different parts of the world, such as rice in the Far East, mechanisms to produce disease resistant plants, receive
beans in Central and South America, cassava, cacao, extensive coverage. It is recognized that some of the
and sorghum in Africa, and tropical fruits such as citrus, included material in Chapters 4 (Genetics of Disease),
papaya, coconut, and coffee in the Americas, and so on. 5 (How Pathogens Attack Plants), and 6 (How Plants
Instructors can pick and choose to study, in the class- Defend Themselves against Pathogens) may be both
room and, if possible, in the laboratory, whatever dis- too much for students taking plant pathology for the
eases of whichever crops they deem most significant for first time and somewhat difficult to follow and com-
the particular area and for the ever-shrinking world we prehend. However, the importance of that material to
all live in. the future development of plant pathology as a science
The overall arrangement of this edition is similar to and its potential future impact on control of plant
that of previous editions. However, all aspects of the diseases is so great that its inclusion is considered justi-
book have been thoroughly updated and illustrated. fied if only to expose and initiate the students to these
Newly discovered diseases and pathogens are described, developments.
and changes in pathogen taxonomy and nomenclature There are numerous colleagues to whom I am
are incorporated in the text. Changes or refinements in indebted for suggestions and for providing me with
plant disease epidemiology and new approaches and numerous slides or electronic images of plant disease
new materials used for plant disease control are dis- symptoms or plant pathology concepts that are used in
cussed. The chapters on diseases caused by prokaryotes the book. Their names are listed in the legend(s) of the
(bacteria and mollicutes), especially the one on diseases figures they gave me and in the list of “Photo Credits.”
caused by plant viruses and viroids, have been revamped I would particularly like to express my sincere appreci-
due to the large amount of new information published ation and thanks to Dr. Ieuan R. Evans of the
in recent years about such pathogens and diseases. And Agronomy Unit of the Alberta Agriculture, Edmonton,
in all cases, partial tables of contents have been added Alberta, Canada, who, as editor of the slide collection
to each chapter and to its main subdivisions for better of the Western Committee on Plant Disease Control,
clarity and understanding of the arrangement and inclu- provided me with hundreds of excellent slides and per-
sion of the topics in the appropriate subdivisions. A new mission to use them in the book. I also thank Dr. Wen
feature that has been added to the book is the presen- Yuan Song for reviewing the chapter on “How Plants
tation of a number of topics of special interest in sepa- Defend Themselves against Pathogens.” Finally, I again
rate boxes. In these, the various topics are approached thank publicly my wife Annette for the many hours she
from a different angle and highlight the importance of spent helping me organize, copy, scan, and reorganize
the topic whether it has historical, political, or scientific the many slides, prints, and diagrams used in this book.
significance. Special attention has also been given to Not only did she do it better, she also did it faster than
highlighting the historical developments in plant pathol- I could have done it.
ogy and the scientists or others who contributed signif-
icantly to these developments.
As in other recent editions, much of the progress in George N. Agrios
plant pathology has been in the areas of molecular July 2004
AFM.qxd 11/24/04 9:55 PM Page xxi

Photo Credits

he need for high-quality photographs to include in Agriculture, Winnipeg, Manitoba; and C. Richard,

T this book necessitated the request of appropriate
photographs from colleagues around the world.
All of them responded positively and I am very thank-
Agriculture Canada, Sainte-Foy, Quebec.
I am equally indebted to Dr. Gail Wisler, Chair, Plant
Pathology Department, University of Florida, for allow-
ful to all of them. I am particularly indebted to the ing me to use whatever slides of the departmental Plant
following individuals and organizations who, although Disease Clinic would be useful in illustrating the book.
I was asking from them one or a few photographs, sent Since all of the slides were stamped with the name of
me those plus all the related or other pertinent photo- Dr. G. W. Simone, and some of them were undoubtedly
graphs that I might want to use in the new edition of taken by him while he was an Extension Plant Patholo-
the book. Moreover, several of them offered to give me gist in charge of the Plant Disease Clinic in the Depart-
any other photographs they had and which I might want ment, now retired, I would like to express my thanks to
to use. Dr. Simone also.
I am particularly indebted to Dr. Ieuan R. Evans of I am also thankful to several other organizations that
the Agronomy Unit, Agriculture, Food, and Rural gave me permission to use many of their photographs
Development of Alberta, Canada, for providing me with and offered to give me any others I might need. They
several hundreds of slides put together by the Western include the Extension Service of the University of
Committee on Plant Diseases (WCPD) for general use Florida Institute of Food and Agricultural Sciences
for educational purposes. Those contributing slides (UF/IFAS), the American Phytopathological Society, and
through the WCPD include P. K. Basu, Agriculture several United States Department of Agriculture (USDA)
Canada, Ottawa, Ontario; J. G. N. Davidson, Agric. Laboratories. I am particularly thankful to the USDA
Canada, Beaverlodge, Alberta; P. Ellis, Agric. Canada, Forest Service along with the University of Georgia who,
Vancouver, British Columbia; I. R. Evans, Agric. through “Forestry Images” and “Bugwood Network,”
Canada, Edmonton, Alberta; G. Flores, Agric. Canada, provided me with several images of forest tree diseases.
Ottawa, Ontario; E. J. Hawn, Agric. Canada, Leth- I am particularly indebted to the following col-
bridge, Alberta; R. J. Howard, Alberta Agriculture, leagues, listed alphabetically, each of whom gave me
Brooks, Alberta; H. C. Huang, Agriculture Canada, numerous slides or electronic images and offered to give
Lethbridge, Alberta; J. E. Hunter, NYAES, Geneva, New me as many more of their photographs as I needed: Dr.
York; G. A. Nelson, Agriculture Canada, Lethbridge, Eduardo Alves, Federal University of Lavras, Brazil;
Alberta; R. G. Platford, Manitoba Department of Dr. Mohammad Babadoost, University of Illinois; Dr.

xxi
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xxii P H OTO C R E D I T S

Edward L. Barnard, Florida Division of Forestry, Forest University of Hawaii; Dr. Catherine Feuillet, University
Health Section; Dr. Benny D. Bruton, USDA, ARS, Lane, of Zurich; Dr. Robert L. Forster, University of Idaho; Dr.
Oklahoma; Dr. David J. Chitwood, USDA, Nematology L. Giunchedi, University of Bologna, Italy; Dr. Tim
Lab, Beltsville, Maryland; Dr. Daniel R. Cooley, Uni- Gottwald, USDA, Ft. Pierce, Florida; Dr. James H.
versity of Massachusetts; Dr. Danny Coyne, CGIAR, Graham, University of Florida; Dr. Sarah Gurr, Oxford
intern. Institute Tropical Agriculture, Ibadan, Nigeria; University, UK; Dr. Everett Hansen, Oregon State Uni-
Richard Cullen, University of Florida; Dr. L. E. Datnoff, versity; Dr. Mary Ann Hansen, Virginia Tech University;
University of Florida; Dr. Donald W. Dickson, Univer- Dr. Thomas C. Harrington, Iowa State University; Dr.
sity of Florida; Dr. Michel Dollet, CIRAD, Montpellier, Robert Hartzler, Iowa State University; Dr. Robert
France; Dr. Michael Ellis, Ohio State University; Mark Harveson, University of Nebraska; Dr. Kenneth D.
Gouch, University of Florida; Dr. Edward Hellman, Hickey, Pennsylvania State University; Dr. Richard B.
Texas A&M University; Dr. Ernest Hiebert, University Hine, University of Arizona; Dr. Molly E. Hoffer,
of Florida; Dr. Donald L. Hopkins, University of Oregon State University; Dr. Harry Hoitink, Ohio State
Florida; Jackie Hughes, Intern. Institute of Tropical University; Dr. Tom Isakeit, Texas A&M University; Dr.
Agriculture, Ibadan, Nigeria; Dr. Bruce Jaffee, Univer- Ramon Jaime, USDA, New Orleans; Dr. Wojciech
sity of California; Dr. Alan L. Jones, Michigan State Uni- Janisiewicz, USDA, Appalachian Fruit Res., West
versity; Dr. Daniel E. Legard, University of Florida; Dr. Virginia; Dr. P. Maria Johansson, Plant Pathology and
Patrick E. Lipps, Ohio State University; Dr. Don E. Biocontrol Unit, Sweden; Dr. R. Johnston, USDA; Dr.
Mathre, Montana State University; Dr. Robert J. Robert Johnston, Montana State University; Dr. Linda
McGovern, University of Florida; Dr. Robert T. McMil- Kinkel, University of Minnesota; Dr. Jurgen Kranz, Uni-
lan, Jr., University of Florida; Dr. Charles W. Mims, Uni- versity of Giessen, Germany; Dr. Richard F. Lee, Uni-
versity of Georgia; Dr. Krishna S. Mohan, University of versity of Florida; Dr. Mark Longstroth, Michigan State
Idaho; Dr. Lytton John Musselman, American Univer- University; Dr. Rosemary Loria, Cornell University; Dr.
sity of Beirut, Lebanon; Dr. Steve Nameth, Ohio State Otis Maloy, Washington State University; Dr. Douglas
University; Dr. Joe W. Noling, University of Florida; Dr. H. Marin, Banana Development Corp., San Jose, Costa
Kenneth I. Pernezny, University of Florida; Dr. Jay W. Rica; Dr. Don Maynard, University of Florida; Dr. Patri-
Pscheidt, Oregon State University; Dr. H. David cia McManus, University of Wisconsin; Dr. Glenn
Thurston, Cornell University; Dr. James W. Travis and Michael, Appalachian Fruit Res., West Virginia; Dr.
Jo Rytter, Pennsylvania State University; Dr. Tom Van Themis Michailides, University of California; Dr. Gary
Der Zwet, USDA, retired; Dr. David P. (Pete) Weingart- Munkvold, Pioneer Hybrid Int., Johnston, Fowa; Dr.
ner, University of Florida; and Dr. Tom Zitter, Cornell Cynthia M. Ocamb, Oregon State University; Dr. Laud
University. A. Ollennou, Cocoa Research Institute, Ghana; Dr.
I am equally thankful to the following colleagues, Tapio Palva, University of Helsinki, Finland; Dr. Frank
also listed alphabetically, who provided me with the Phleger (for C. M. Christensen), University of Min-
photographs I requested of them: Dr. Luis Felipe Arauz, nesota; Dr. Mary Powelson, Oregon State University;
Universitad de Costa Rica, San Jose; Dr. Gavin Ash, Dr. David F. Ritchie, North Carolina State University;
Charles Sturt University, Australia; Dr. Donald E. Aylor, Dr. Chester Roistacher, University of California; Dr.
Connecticut Agric. Experimental Station, New Haven; John P. Ross, North Carolina State University; Dr.
Dr. Ranajit Bandyopathyay, CGIAR, Nigeria; Dr. Randall Rowe, Ohio State University; Dr. Robert Stack,
George Barron, University of Guelph; Dr. Gwen A. North Dakota State University; Dr. James R. Steadman,
Beattie, Iowa State University; Dr. Dale Bergdahl, Uni- University of Nebraska; Dr. Brian J. Steffenson, Univer-
versity of Vermont; Dr. Ian Breithaupt, AGPP, FAO; Dr. sity of Minnesota; Dr. R. J. Stipes, Virginia Tech Uni-
Scott Cameron, International Paper Co.; Dr. Mark versity; Dr. Virginia Stockwell, Oregon State University;
Carlton, Iowa State University; Dr. Asita Chatterjee, Dr. Krishna V. Subbarao, University of California; Dr.
University of Missouri; Dr. C. M. Christensen (via Dr. Pavel Svihra, University of California; Dr. Beth Teviot-
Frank Pfleger), University of Minnesota; Dr. William T. dale, University of California; Dr. L. W. Timmer, Uni-
Crow, University of Florida; Dr. Howard Davis, Scottish versity of Florida; Dr. Greg Tylka, Iowa State University;
Agricultural Research Institute, UK; Dr. Michael J. Dr. S. V. van Vuuren, ARC-ITSC, Nelspruit, South
Davis, University of Florida; Dr. O. Dooling, USDA Africa; Dr. John A. Walsh, Horticultural Research
Forest Service; Dr. Sharon Douglas, Connecticut Agric. Institute, UK; Dr. Robert K. Webster, University of
Experimental Station, New Haven; Dr. Robert A. Dunn, California, Davis; Dr. Wickes Westcott, Clemson
University of Florida; Dr. D. Dwinell, USDA Forest University; Dr. Carol Windels, University of Minnesota;
Service; Dr. D. M. Elgersma, The Netherlands; Shep Dr. X. B. Yang, Iowa State University; and Dr. Ulrich
Eubanks, University of Florida; Dr. Stephen Ferreira, Zunke, Hamburg, Germany.
AFM.qxd 11/24/04 9:55 PM Page xxiii

About the Author

Professor George N. Agrios was born in Galarinos, became the standard plant pathology text throughout
Halkidiki, Greece. He received his B.S. degree in horti- the world.
culture from the Aristotelian University of Thessaloniki, In the meantime, Dr. Agrios served on several depart-
Greece, in 1957, and his Ph.D. degree in plant pathol- mental, college and university committees as well as
ogy from Iowa State University in 1960. Following grad- committees of the northeastern division of the American
uation he served 2 years as an officer in the Engineering Phytopathological Society (APS) and of the national
Corps of the Greek army. In January 1963 he was hired APS. He was elected president of the northeastern divi-
as an assistant professor of plant pathology at the Uni- sion (1980) of APS. He was instrumental in founding
versity of Massachusetts at Amherst. His assignment the APS Press, of which he served as the first editor-in-
was 50% teaching and 50% research on viral diseases chief (1984–1987). He was elected vice-president of APS
of fruits and vegetables. His teaching included courses in 1988, serving as vice-president , president-elect, and
in introductory plant pathology, general plant pathol- president (1990 and 1991). In 1988, professor Agrios
ogy, plant virology, and diseases of florist’s crops. His accepted a position as chairman of the Plant Pathology
research included studies on epidemiology, genetics, and Department of the University of Florida, overseeing
physiology of viral diseases of apple, cucurbits, pepper, approximately 50 Ph.D. plant pathologist faculty. Half
and corn, in which he directed the studies of 25 gradu- of the faculty were located at the university campus in
ate students and published numerous journal publica- Gainesville, Florida, while the others worked at 1 of 13
tions. Dr. Agrios was promoted to associate professor in agricultural research centers throughout the state of
1969 and to professor in 1976. Florida where they studied all types of diseases of
In 1969, he published the first edition of the textbook various crops. In 1999, the Florida Board of Regents
“Plant Pathology” through Academic Press. The book approved the establishment of the new and unique
was adopted for plant pathology classes at almost Doctor of Plant Medicine Program and professor Agrios
all universities of the United States and Canada and of was appointed its first director. In 2002, Dr. Agrios
most other English-speaking countries. The first edition relinquished his position as chairman of the Plant
was later followed by the 2nd edition (1978), 3rd Pathology Department to concentrate on his duties as
edition (1987), and 4th edition (1997). The book was director of the Doctor of Plant Medicine Program. In
translated into several major languages, including June 2002, however, health reasons forced Dr. Agrios to
Spanish, Arabic, Chinese, Korean, and Indochinese, and retire from the University of Florida.

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