Ecological Management of Agricultural Weeds (2001)(en)(544s)

545 Pages·2001·6.36 MB·English

by  Liebman M.

Ecological Management ofAgricultural Weeds
Concerns over environmental and human health impacts ofconventional
weed management practices,herbicide resistance in weeds,and rising costs
ofcrop production and protection have led agricultural producers and
scientists in many countries to seek strategies that take greater advantage
ofecological processes.Thisbook provides principles and practices for
ecologically based weed management in a wide range oftemperate and
tropical farming systems.After examining weed life histories and processes
determining the assembly ofweed communities,the authors describe how
tillage and cultivation practices,manipulations ofsoil conditions,
competitive cultivars,crop diversification,grazing livestock,arthropod and
microbial biocontrol agents,and other factors can be used to reduce weed
germination,growth,competitive ability,reproduction,and dispersal.
Special attention is given tothe evolutionary challenges that weeds pose and
the roles that farmers can play in the development ofnew weed
management strategies.
matt liebmanis an Associate Professor in the Department ofAgronomy
at Iowa State University.He is the co-editor ofWeed Management in Agro-
Ecosystems: Ecological Approaches(1988).
charles l. mohleris a Senior Research Associate in the Department of
Crop and Soil Science at Cornell University.He is an associate editor ofthe
journal Weed Science.
charles p. staveris a project co-coordinator at CATIE(Center for
Teaching and Research in Tropical Agriculture),Nicaragua,where he works
on integrated pest management.

Ecological
Management
of Agricultural
Weeds
Written and Edited by
Matt Liebman
Iowa State University
Charles L. Mohler
Cornell University
Charles P. Staver
Centro Agronómico Tropical de Investigación y Enseñanza,Managua,Nicaragua
         
The Pitt Building, Trumpington Street, Cambridge, United Kingdom
  
The Edinburgh Building, Cambridge CB2 2RU, UK
40 West 20th Street, New York, NY 10011-4211, USA
477 Williamstown Road, Port Melbourne, VIC 3207, Australia
Ruiz de Alarcón 13, 28014 Madrid, Spain
Dock House, The Waterfront, Cape Town 8001, South Africa
http://www.cambridge.org
©Cambridge University Press 2004
First published in printed format 2001
ISBN 0-511-01764-2 eBook (netLibrary)
ISBN 0-521-56068-3 hardback
Contents
Preface ix
1 Weed management: a need for ecological approaches 1
Matt Liebman
Introduction 1
Weed management objectives 2
Herbicide sales and use 5
Unintended impacts ofherbicide use 8
Weed management and farm profitability 19
Transitions to ecological weed management 24
Summary 30
2 Weed life history: identifying vulnerabilities 40
Charles L. Mohler
Weeds from an ecological perspective 40
The life history ofweeds 42
Dormancy and germination 46
Survival ofweed seeds in the soil 53
Hazards ofestablishment 60
Vegetative growth and crop–weed competition 62
Survival after emergence 67
Life span and seed production 71
Dispersal ofseeds and ramets 75
Conclusions 84
3 Knowledge,science,and practice in ecological weed
management: farmer–extensionist–scientist interactions 99
Charles P. Staver
Introduction 99
Knowledge and technology for weed management: an historical
perspective 100
vi Contents
Contrasting perspectives offarmers,extensionists,and scientists on
weeds 104
Weed patchiness and uncertainty: the challenge to improving weed
management 109
Three approaches to farmer management ofweed patchiness and
uncertainty 113
Adaptive management and farmer–extensionist–scientist interactions 117
Participatory learning for ecological weed management: a proposal 118
Farmers,extensionists,and scientists learning together:four examples 127
Aconcluding note 133
4 Mechanical management ofweeds 139
Charles L. Mohler
Introduction 139
Tillage: pros and cons 140
Mechanical management ofperennial weeds 141
Effects oftillage on weed seedling density 151
Basic principles ofmechanical weeding 169
Machinery for mechanical weeding 173
Comparison ofchemical and mechanical weed management 190
Directions for future research 192
5 Weeds and the soil environment 210
Matt Liebman and Charles L. Mohler
Introduction 210
Temperature management 212
Water management 215
Fertility management 220
Crop residue management 229
Toward the integration ofweed and soil management 250
6 Enhancing the competitive ability ofcrops 269
Charles L. Mohler
Introduction 269
Crop density 270
Crop spatial arrangement 281
Crop genotype 287
Phenology 297
Conclusions 305
7 Crop diversification for weed management 322
Matt Liebman and Charles P. Staver
Introduction 322
Cropdiversityinconventional,traditional,andorganicfarmingsystems 323
Principles guiding crop diversification for weed management 325
Crop rotation 326
Intercropping 336
Contents vii
Agroforestry 351
Obstacles and opportunities in the use ofcrop diversification for weed
management 363
8 Managing weeds with insects and pathogens 375
Matt Liebman
Introduction 375
Conservation ofresident herbivores and pathogens 377
Inoculative releases ofcontrol agents 380
Inundative releases ofcontrol agents 391
The integration ofmultiple stress factors 398
Moving ahead with weed biocontrol 400
9 Livestock grazing for weed management 409
Charles P. Staver
Introduction 409
Matching grazing strategies with weed problems 410
Weed control through herbivory in short-cycle crops 420
Aftermath and fallow grazing for weed control 421
Grazing for weed control in tree crops 423
Grazing for weed control in pastures and rangelands 427
Research directions 435
10 Weed evolution and community structure 444
Charles L. Mohler
Introduction 444
Formation and management ofweed communities 445
Human-dominated ecosystems as an evolutionary context 454
Origins ofweeds 455
Weed genecology 463
Managing the adaptation ofweed populations 474
Controlling the spread ofnew weeds 481
Conclusions 484
11 Weed management: the broader context 494
Charles L. Mohler, Matt Liebman, and Charles P. Staver
Introduction 494
Ifecological weed management is effective,why do farmers rely heavily on
herbicides? 495
Feeding a growing human population 502
Developing an environment for research on ecological weed
management 506
Implementing ecological weed management 510
Taxonomic index 519
Subject index 525

Preface
Of the many books that have been written about weed management, most
have focused on the use ofherbicides.This volume is different.Instead ofpro-
viding information about chemical weed control technologies,the emphasis
here is on weed management procedures that rely on manipulations of eco-
logical conditions and relationships. By focusing on ecologically based
methods ofmanagement,we have been able to provide in-depth treatment of
subjects that most weed science books treat only briefly.
Although the reader will find much information on the ecology of weeds
here,the primary purpose ofthe book is not to explain weed ecology.Rather,
our intent is to elucidate the role of ecological principles in weed manage-
ment.We believe that ecology can provide a theoretical basis for weed science,
much as physics provides a theoretical basis for engineering and biology acts
as the theoretical basis for medicine.Accordingly, throughout this book we
show ways in which insights into ecological processes provide explanations
for the successes and failures ofweed management and avenues for develop-
ing better management strategies.
This volume could be used as a textbook for an advanced course in weed
management, but it was not written primarily for that purpose.Rather,we
have attempted to offer the reader a critical analysis and synthesis ofthe liter-
ature on ecological weed management and relevant aspects of weed ecology.
Several goals motivated this review process. First, we wanted to identify
clearly the principles that underlie ecological management practices.Second,
we wanted to assess the strengths and weaknesses of specific weed manage-
ment tactics in different cropping systems.Third,we sought to identify the
current gaps in understanding of ecological approaches to weed manage-
ment.As we wrote, we regularly asked ourselves,“What are the interesting
research questions relating to this subject,and how could they be answered?”
Fourth,we wanted to point out possible new roles for weed scientists within
i