Weed Research: Expanding Horizons

This book presents the most up-to-date and comprehensive guide to the current and potential future state of weed science and research. Weeds have a huge effect on the world by reducing crop yield and quality, delaying or interfering with harvesting, interfering with animal feeding (including poisoning), reducing animal health and preventing water flow. They are common across the world and cost billions of dollars’ worth of crop losses year on year, as well as billions of dollars in the annual expense of controlling them. An understanding of weeds is vital to their proper management and control, without which the reduction in crop yields that they would cause could lead to mass starvation across the globe. Topics covered include weed biology and ecology, control of weeds and particular issues faced in their control. Authored and edited by internationally renowned scientists in the field all of whom are actively involved in European Weed Research Society working groups, this succinct overview covers all the relevant aspects of the science of weeds. Weed Research: Expanding Horizons is the perfect resource for botanists, horticultural scientists, agronomists, weed scientists, plant protection specialists and agrochemical company personnel.

Table of Contents:
List of Contributors xv Preface xix 1 Weed Science Research: Past, Present and Future Perspectives 1 Robert J. Froud?]Williams Introduction 1 Factors Influencing the Weed Flora 2 Succession 2 Clean Seed 3 Rotation 3 Fallow 4 Cultivation 5 Straw Burning 5 Soil Amelioration, Drainage and Fertiliser Use 5 Nitrogen 6 Herbicides 6 Consequences of Changing Practices 9 Changing Weed Floras 9 Episodic Decline 13 Weed Spatial Distribution 13 History of Weed Science in the UK and Origins of the Weed Research Organisation 14 Origins of the European Weed Research Society 17 Weed Research (Journal): Origin of Papers and Discipline 18 Changing Attitudes to Weeds 18 Set?]Aside and Agri?]Environment 19 Weeds, Climate and Invasive Aliens 20 Future Directions (Quo Vadis?) 21 Environmental Weed Management 21 Evolutionary Genetics and the Role of Molecular Ecology 22 Is there a Need for a Change of Emphasis? 22 Conclusion 23 Acknowledgements 24 References 24 2 Descriptive and Mechanistic Models of Crop–Weed Competition 33 Lammert Bastiaans and Jonathan Storkey Introduction 33 Descriptive Models for Yield Loss Due to Weed Competition 34 The Hyperbolic Yield Loss–Weed Density Curve 34 Accounting for Differences in Relative Time of Emergence 36 Other Factors Influencing Parameter i 39 Management Aimed at Modifying Crop–Weed Competitive Relations 40 A Quantitative Characterisation of Differences in Weed?]Suppressive Ability of Crop Cultivars 45 Mechanistic Models for Crop–Weed Competition 46 Structure and Function of Process?]Based Models for Crop–Weed Competition 46 A First Application: Ideotyping of More Weed?]Suppressive Cultivars 50 A Second Application: Predicting the Impact of Climate Change on Weed Distribution 51 Conclusion 55 References 56 3 Approaches and Objectives of Arable Weed Species Mapping: Where Next? 61 Hansjörg Krähmer and Paolo Bàrberi Weed Species Mapping: Why? 61 Scientific Literature: State of the Art 62 Mapping Herbicide?]resistant Biotypes 63 Mapping Invasive Species 63 Weed Species Mapping: Who? 65 Weed Species Mapping: Where and What? 66 Maps of Weeds in European Arable Crops 66 Field?]Level Mapping 71 Weed Species Mapping: How? 72 Geo?]Referencing 72 Timing of Assessment 74 Sampling Parameters 74 Documentation and Maps 74 What to Conclude from Weed Mapping Data? 75 Weed Mapping: Where to Go? 76 Acknowledgements 80 References 80 4 Seed Biology and Population Dynamics 85 Kirsten S. Tørresen, Laila M. Karlsson and Jose Luis Gonzalez?]Andujar Introduction 85 Seed Biology 86 Seed Production and Dispersal 86 Seed?]Bank 88 Germination and Dormancy 90 Germination 90 Dormancy 91 Sprouting from Vegetative Plant Parts 96 Predicting Seedling Emergence 97 Empirical Models 97 Mechanistic Models 97 Challenges in Predicting Emergence 98 Importance for Weed Control 99 Population Dynamics 100 Dynamics in Time and Space 100 Modelling 100 Non?]Spatial Models 101 Spatial Models 103 Practical Applications in Weed Science 103 Evaluation of Management Systems 103 Decision Support Systems 104 Challenges in Modelling Population Dynamics 104 Future Prospects 104 Conclusion 105 Acknowledgements 106 References 106 5 Weeds and Biodiversity 115 Bärbel Gerowitt, Paolo Bàrberi, Henri Darmency, Sandrine Petit, Jonathan Storkey and Paula Westerman Introduction 115 Arable Weeds in the Context of Biodiversity 116 Functional Biodiversity 116 Agronomic Services and Disservices Associated with Weeds 117 Genetic Diversity in Weeds 117 How to Measure Genetic Diversity 119 At Which Scale Can Genetic Diversity Be Described? 120 Why Is It Important to Understand Weed Genetic Diversity? 121 Rare Weed Species as Objects of Conservation 122 Drivers of Arable Weed Declines 123 The Rare Weed Trait Syndrome 124 Conserving Rare Weed Communities 124 Weeds in Food Chains of Arable Systems 124 Factors Influencing Seed?]Based Food Webs in Agroecosystems 126 Weed Seed Production 126 Within?]Season Temporal Variability 126 Between?]Season Temporal Variability 126 Spatial Variability 127 Seed Morphology and Chemistry 127 Weed Diversity 127 Current Status of Seed?]Based Food Webs on Farms and Management Options 127 Diversity of Weeds and Arable Management 129 Site Conditions of Arable Fields Filter for Weed Communities 129 Methods to Identify and Separate the Influence of Arable Site and Arable Management on Weed Diversity 130 Arable Management Determines Weed Diversity 131 Weed Diversity Versus Weed Abundance 131 Diversity in Weeds Facilitates Management Options 132 Diversity of Weeds in a Landscape Context 133 The Landscape Context of Weeds 133 Conducting Landscape?]Scale Weed Studies 134 Landscape Effects on Weed Biodiversity: Empirical Evidence 135 Biodiversity of Weeds and Public Interest 136 Field Margin Programmes 136 Encouraging Weed Diversity in Farming 136 Conclusions and Perspectives 137 References 138 6 Optimising Herbicide Performance 149 Per Kudsk Introduction 149 Herbicide Classification 150 Optimising Herbicide Performance: How to Study It 151 Biotic Factors 154 Weed Flora 154 Weed Growth Stage 156 Crop Competition 157 Abiotic Factors 158 Soil Texture 158 Climatic Conditions 159 Light 159 Temperature 160 Humidity 161 Precipitation 162 Soil moisture 163 Wind 164 Concluding Remarks 164 Application Technique 165 Adjuvants 166 Mixtures with Other Herbicides 168 Concluding Remarks and Future Challenges 170 References 172 7 Herbicide Resistance in Weeds 181 Stephen Moss Historical Perspective 181 What Is Herbicide Resistance? 182 The Worldwide Occurrence of Resistant Weeds 183 Herbicide Mode of Action and Risk of Resistance 185 Resistance Mechanisms 188 Target?]Site Resistance 188 PSII (Triazines) 189 ALS Inhibitors 190 ACCase Inhibitors 190 Other Herbicide Classes 191 Non?]Target?]Site Resistance 191 Reduced Herbicide Uptake 193 Reduced Herbicide Translocation 193 Enhanced Herbicide Metabolism 194 Evolution of Herbicide Resistance 194 Initial Frequency of the Resistance Trait and Size of Weed Population 195 Genetic Basis of Resistance 197 Selection Pressure 199 Frequency of Herbicide Use 199 Persistence of the Herbicide and Pattern of Weed Emergence 199 Intrinsic Activity of the Herbicide and Degree of Resistance Conferred by the Resistance Mechanism(s) 200 Specificity of the Herbicide: Number of Species the Herbicide Controls 201 Seed Bank in the Soil 201 Resistance Risk 201 Prevention and Management of Herbicide Resistance 203 Detection of Resistance in the Field 203 Integrated Weed Management 203 Non?]Chemical Control Methods 204 Herbicidal Control 204 Alternative Herbicides 204 Mixtures, Sequences and Rotations 205 Managing Resistance in Alopecurus Myosuroides (Black?]grass): A Case Study 205 Farmer Psychology: An Under?]Recognised Component of Resistance Management 206 Conclusion 209 References 209 8 Weed Biological Control 215 Richard H. Shaw and Paul E. Hatcher Introduction 215 Definitions of Weed Biocontrol 217 Biocontrol of Weeds in European Extensive Agriculture 218 Cirsium Arvense 219 Rumex Species 221 Biocontrol of Weeds in Intensive Agriculture 222 Biocontrol of Non?]native Weeds 224 Ambrosia 228 In Summary 230 Combining Biocontrol with Other Weed Control Techniques 230 Combining with Other Non?]Chemical Control Methods 231 Combination with Herbicides 232 Arthropod Biocontrol Agents 232 Fungal Biocontrol Agents 233 Legislation, Responsibilities and Drivers 234 Arthropods 234 Fungi 235 Conclusion 235 References 236 9 Non?]Chemical Weed Management 245 Bo Melander, Matt Liebman, Adam S. Davis, Eric R. Gallandt, Paolo Bàrberi, Anna?]Camilla Moonen, Jesper Rasmussen, Rommie van der Weide and Francesco Vidotto Introduction 245 Preventive and Cultural Weed Control 246 Objectives, Principles and Practices 247 Objective 1: Reduce Weed Density 247 Objective 2: Reduce Damage Per Surviving Weed 248 Objective 3: Prevent Undesirable Shifts in Weed Community Composition 249 Current Adoption and Challenges 250 Cover Crops and Mulches 250 Mechanisms of Cover Crop–Weed Interactions 251 Challenges for Research 252 Mechanical Weed Control 253 How It Works 256 Shortcomings 257 Challenges for Research 258 Thermal Weed Control 259 Thermal Weed Control in Practice 262 Challenges for Research 263 Conclusion 263 References 264 10 Invasive Plants 271 Christian Bohren Introduction 271 Why Do Invasive Plants Symbolise such a Threat? 271 Invasive Weeds and Human Health 271 Ambrosia 272 Giant Hogweed 273 Weedy Crops, Super Weeds and Mimetic Weeds 274 Invasive Aquatic Weeds 275 Human Intervention 276 Human Curiosity 276 Reasons for Increased Occurrence of Invasive Weeds 276 Responsibility 277 Scientific Prioritisation 278 Popular Prioritisation 278 Implementation 279 Facts Concerning Plant Invasion 280 The Early Beginnings 280 Changing Land Use and Fishery 281 Rapid Adaptation 282 Weeds, Invasives and Climate Change 282 What Makes Plant Invaders so Successful? 283 Can We Predict Plant Invasions? 284 What Has Been Done so Far? 285 Databases 285 European Initiative 285 European Food Safety Agency (EFSA) 288 Euphresco 288 SMARTER 288 Role of the EWRS Invasive Plants Working Group 289 Mission 289 Working Group Activities 289 Ponta Delgada, Azores, Portugal, 2006 289 Osijek, Croatia, 2008 290 Ascona, Switzerland, 2011 290 Montpellier, France, 2014 290 EPPO Trabzon 291 NEOBIOTA 291 Aquatic Weeds 291 Definitions and Plant Lists 291 Definitions 291 Weed 292 Invasive Plant 292 Plant Invader 294 Invasion Trajectory 294 Invasive Species Lists 294 Control Strategies for Invasive Weeds 294 Biological Control Versus Conventional Control 294 Learning to Control Invasions 298 Social and Economic Aspects 300 Anthriscus 300 Japanese Knotweed 300 Bracken 301 Ambrosia 302 Strategies 302 Prevention 302 Early Detection 302 Rapid Response 302 Pest Risk Assessment 303 Species?]Specific Control 303 Conclusion 303 References 306 11 Parasitic Weeds 313 Maurizio Vurro, Alejandro Pérez?] de?]Luque and Hanan Eizenberg Introduction 313 Classification 315 Orobanchaceae (Broomrape Family) 315 Cuscuta 315 Life?]Cycle 316 Broomrapes 316 Dodder 317 Distribution at the European Level, Host Range and Yield Losses 318 Management Strategies 325 Management and Control 325 Biological Control 325 Natural Products 328 Strigolactones and Other Germination Stimulants 329 Nanotechnological Approaches 332 Genetic Resistance 334 Defensive Mechanisms 335 Novel Genetic Approaches 337 Chemical Control of Broomrapes 337 Herbicide?]Resistant Crops for Broomrape Control 340 Developing Models for Optimising Chemical Control of Root Parasitic Weeds 341 Precision Agriculture 342 Conclusion 346 References 346 12 Weed Management Systems in Vegetables 355 Francesco Tei and Euro Pannacci Introduction 355 Weed Flora 357 Weed–Vegetable Crop Interactions 358 Integrated Weed Management 365 Preventive Measures 366 Cultural Methods 366 Crop Rotation 366 Cover?]crops 367 Stale Seed?]Bed Preparation 368 Cultivar Selection 368 Planting Method, Planting Pattern, Row Spacing and Crop Density 368 Physical Weed Control 368 Non?]Living Mulches 369 Solarisation 369 Flaming 369 Steaming 370 Mechanical Weed Control 370 Hand?]Weeding 371 Biological Weed Control 371 Chemical Weed Control 371 Conclusions and Perspectives 377 References 380 13 Perennial Weeds 389 Paul E. Hatcher Introduction 389 Perennating Structures 390 Fragmentation, Nutrient Reserves and Regrowth 391 Dormancy of Vegetative Structures 392 Grassland Perennials 392 Perennials in Organic Arable Systems 394 Perennials of Southern European Agriculture 396 Cyperus Species 397 Sorghum Halepense 398 Bracken 399 Conclusion: Perennial Weeds in the Future 401 Climate Change 401 Reduced Tillage 402 References 403 Index 000

About the Author :
PAUL E. HATCHER is Associate Professor in Applied Ecology in the School of Biological Sciences at the University of Reading, working on perennial weed control and biological control of weeds and insects. He has been a member of the EWRS since 1993, and was Chair of the EWRS Biological Control working group for many years. He is Chair of the Editorial Board for the Wiley-Blackwell journal Weed Research, and a member of the Board of the EWRS. He is also a member of the DEFRA steering group on weed biological control. ROBERT J. FROUD-WILLIAMS was Senior Lecturer in Weed Science in the School of Biological Sciences at the University of Reading and has research interests in weed ecology, agri-environment and integrated weed management. During his career within the university he supervised more than forty postgraduate students. He has been a member of EWRS since 1980 and was elected Vice President in 2001 and President in 2003 in addition to his former role as National Representative. He has been a member of several external committees including BCPC Expert Weeds and for eighteen years was Chairman of the UK Weed Liaison Group representing publicly-funded weed science in the UK. He also was member of various committees including Defra Sustainable Arable Link, Association of Applied Biology Weeds and Agronomy Group, member of the advisory board for Aquatic Plant Management Committee and steering committee of the Arable Plants Group within Plantlife.