Preface ........................................................ xv
Chapter 1 Introduction ......................................... 1
Literature Cited ......................................... 12
Chapter 2 Weeds—The Beginning ................................. 15
I. Definition of the Word Weed .............................. 16
II. Characteristics of Weeds ................................. 20
III. Harmful Aspects of Weeds ................................. 23
A Plant Competition ..................................... 23
B Added Protection Costs ................................ 23
C Reduced Quality of Farm Products ...................... 27
D Reduced Quality of Animals ............................ 27
E Increased Production and Processing Costs ............. 30
F Water Management ...................................... 31
G Human Health .......................................... 32
H Decreased Land Value and Reduced Crop Choice .......... 32
I Aesthetic Value ....................................... 33
IV. Cost of Weeds ............................................ 33
Things to Think About .................................... 38
Literature Cited ......................................... 39
Chapter 3 Weed Classification ................................. 43
I. Phylogenetic Relationships ............................... 45
II. A Note About Names ....................................... 46
III. Classification Methods ................................... 48
A Type of Plant ......................................... 48
B Habitat ............................................... 48
Cropland .............................................. 48
Rangeland ............................................. 48
Forests ............................................... 49
Aquatic ............................................... 49
Environmental Weeds ................................... 50
Parasitic Weeds ....................................... 51
C Life History .......................................... 53
Annuals ............................................... 54
Biennials ............................................. 55
Perennials ............................................ 55
Things to Think About ................................. 57
Literature Cited ...................................... 57
Chapter 4 Ethnobotany ......................................... 59
I. Food for Humans .......................................... 60
II. Feed for Animals ......................................... 64
III. Medical Uses ............................................. 66
IV. Agricultural Uses ........................................ 68
V. Ornamental Uses .......................................... 69
VI. Insect or Disease Traps .................................. 70
VII. Pollution Control ........................................ 72
VIII. Other Uses ............................................... 74
Things to Think About .................................... 76
Literature Cited ......................................... 76
Chapter 5 Weed Reproduction and Dispersal ..................... 79
I. Seed Production .......................................... 80
A Seed Size ............................................. 81
B Seed Abundance ........................................ 81
C Seed Production ....................................... 82
II. Seed Dispersal ........................................... 88
A Mechanical ............................................ 88
B Wind .................................................. 90
C Water ................................................. 91
D Human-Aided ........................................... 93
E Animal-Aided .......................................... 96
F Machinery ............................................. 98
G Mimicry .............................................. 100
H Other ................................................ 100
I Consequences of Weed Dispersal ....................... 100
III. Seed Germination—Dormancy ............................... 101
A Causes ............................................... 103
Light ................................................ 104
Immature Embryo ...................................... 105
Impermeable Seed Coat ................................ 106
Inhibitors ........................................... 106
Oxygen ............................................... 106
Temperature .......................................... 106
After-Ripening Requirement ........................... 107
B Classes of Dormancy .................................. 107
IV. Vegetative or Asexual Reproduction ...................... 114
Things to Think About ................................... 118
Literature Cited ........................................ 118
Chapter 6 Weed Ecology ....................................... 123
I. Human Influences on Weed Ecology ........................ 125
II. The Weed-Crop Ecosystem ................................. 128
III. Environmental Interactions .............................. 130
A Weeds and Climate .................................... 130
B Edaphic Factors ...................................... 132
C Weeds and Biota ...................................... 133
Similarity of Seed Size .............................. 133
Time of Seed Germination and Formation ............... 133
Tillage, Rotation, and Harvest Practices ............. 134
IV Fundamental Ecological Concepts ......................... 136
A Species .............................................. 136
B The Community ........................................ 143
C Ecological Succession ................................ 144
D Interactions Between Weeds and Other Crop Pests ...... 144
V. Plant Competition ....................................... 146
A Plant Competition Defined ............................ 148
B Factors That Control the Degree of Competition ....... 148
C Competition for Nutrients ............................ 151
D Competition for Water ................................ 156
E Competition for Light ................................ 161
F Factors for Which Plants Do Not Compete .............. 163
VI. Plant Characteristics and Competitiveness ............... 164
VII. The Relationship Between Weed Density and Crop Yield .... 165
VIII. Magnitude of Competitive Loss ........................... 169
IX. Duration of Competition ................................. 172
X. Economic Analyses ....................................... 176
XI. Mathematical Models of Competition ...................... 178
Things to Think About ................................... 180
Literature Cited ........................................ 180
Chapter 7 Invasive Plants .................................... 187
I. The Definition of Invasive Species ...................... 187
II. The Identity of Invasive Plant Species .................. 190
III. Why Do Invasions Occur? ................................. 197
IV. The Consequences of Plant Invasions ..................... 203
A Tamarisk/Salt Cedar .................................. 207
B Kudzu ................................................ 208
C Waterhyacinth ........................................ 209
D Purple Loosestrife ................................... 210
V. Management of Invasive Plant Species .................... 214
Things to Think About ................................... 221
Literature Cited ........................................ 221
Chapter 8 Allelopathy ........................................ 227
I. Allelopathic Chemistry .................................. 233
II. Production of Allelochemicals ........................... 235
III. Allelopathy and Weed-Crop Ecology ....................... 237
A Effects on Weed Species .............................. 237
B Weed Interference .................................... 237
C Weed Management ...................................... 238
Things to Think About ................................ 243
Literature Cited ..................................... 243
Chapter 9 The Significance of Plant Competition .............. 247
I. General Considerations .................................. 247
II. Characteristics of Weeds ................................ 255
A Competitive Ability .................................. 255
B Reproductive Characteristics ......................... 256
C Cultural Practices ................................... 257
Things to Think About ................................ 257
Literature Cited ..................................... 257
Chapter 10 Methods of Weed Management and Control ............. 259
I. The Definitions of Weed Prevention, Control,
Eradication, and Management ............................. 260
A Weed Prevention ...................................... 260
B Weed Control ......................................... 261
C Weed Eradication ..................................... 261
D. Weed Management ...................................... 261
II. Weed Prevention ......................................... 262
III. Mechanical Control ...................................... 269
A Hand-Pulling ......................................... 270
B Hand-Hoeing .......................................... 270
C Tillage .............................................. 272
D Mowing ............................................... 285
E Flooding, Salt Water, Draining, and Chaining ......... 286
IV. Nonmechanical Methods ................................... 288
A Heat ................................................. 288
Flaming .............................................. 288
Solarization and Heat ................................ 290
B Mulching ............................................. 292
C Sound and Electricity ................................ 294
D Light ................................................ 295
V. Cultural Weed Control ................................... 295
A Crop Competition ..................................... 295
B Planting Date and Population ......................... 300
C Companion Cropping ................................... 302
D Crop Rotations ....................................... 306
E Fertility Manipulation ............................... 309
VI. Herbicide-Resistant Crops ............................... 311
Things to Think About ................................... 317
Literature Cited ........................................ 317
Chapter 11 Biological Weed Control ............................ 327
I. General ................................................. 327
A Definition ........................................... 328
B Advantages ........................................... 328
C Disadvantages ........................................ 329
D Use Considerations ................................... 331
II. Methods of Application .................................. 335
A Classical, Inoculative, or Importation ............... 336
B Augmentative or Inundative ........................... 337
C Conservation ......................................... 338
D Broad-Spectrum Control ............................... 338
III. Biological Control Agents ............................... 338
A Classical or Inoculative Biological Control .......... 339
Insects .............................................. 339
B Inundative or Augmentative ........................... 342
Fungi ................................................ 342
C Broad-Spectrum Control ............................... 346
Fish ................................................. 346
Aquatic Mammals ...................................... 348
Vertebrates .......................................... 348
IV. Integration of Techniques ............................... 350
Things to Think About ................................... 351
Literature Cited ........................................ 352
Chapter 12 Introduction to Chemical Weed Control .............. 357
I. History of Chemical Weed Control ........................ 358
A The Blood, Sweat, and Tears Era ...................... 358
B The Mechanical Era ................................... 358
C The Chemical Era ..................................... 359
II. Advantages of Herbicides ................................ 367
III. Disadvantages of Herbicides ............................. 374
A Cost ................................................. 374
B Mammalian Toxicity ................................... 375
C Environmental Persistence ............................ 375
D Weed Resistance to Herbicides ........................ 375
E Monoculture .......................................... 381
F Other ................................................ 382
IV. Classification of Herbicides ............................ 383
A Crop of Use .......................................... 383
B Observed Effect ...................................... 388
C Site of Uptake ....................................... 388
D Contact Versus Systemic Activity ..................... 388
E Selectivity .......................................... 389
F Time of Application .................................. 389
G Chemical Structure ................................... 390
H Site/Mechanism of Action ............................. 390
Things to Think About ................................ 391
Literature Cited ..................................... 391
Chapter 13 Properties and Uses of Herbicides .................. 395
I. Introduction ............................................ 395
II. Light-Dependent Herbicides .............................. 398
A. Inhibitors of Photosynthesis ......................... 398
Inhibitors of Photosynthesis at Photosystem II,
Site A ............................................... 399
Inhibitors of Photosynthesis at Photosystem II,
Site A, but with Different Binding Behavior .......... 401
Inhibitors of Photosynthesis at Photosystem II,
Site В ............................................... 402
Inhibitors of Photosynthesis at Photosystem I:
Electron Divertors ................................... 403
B Inhibitors of Pigment Production ..................... 404
Inhibitors of Carotenoid Biosynthesis ................ 404
Inhibitors of Phytoene Desaturase with Blockage of
Carotenoid Biosynthesis .............................. 405
Inhibitors of 1-Deoxy-D-Xyulose 5-Phosphate
Synthatase (DOXP Synthase) ........................... 405
C Cell Membrane Disruptors and Inhibitors .............. 406
Inhibitors of Protoporphyrinogen Oxidase (Protox) .... 406
III. Fatty Acid Biosynthesis Inhibitors ...................... 407
A Inhibitors of Acetyl CoA Carboxylase - ACCase
Inhibitors ........................................... 408
Aryloxyphenoxypropionates ............................ 408
Cyclohexanediones .................................... 410
B Inhibitors of Lipid Synthesis, Not ACCase
Inhibition ........................................... 410
C Inhibition of Biosynthesis of Very Long Chain Fatty
Acids ................................................ 412
IV. Cell Growth Inhibition .................................. 414
A Inhibition of Microtubule Assembly ................... 414
Dinitroanilines ...................................... 414
Other ................................................ 416
B Inhibition of Mitosis ................................ 416
C Inhibition of Cell Wall Synthesis .................... 416
V. Auxin-Like Action—Growth Regulators ..................... 417
A Synthetic Auxins ..................................... 417
Phenoxy Acids ........................................ 418
Arylaliphatic or Benzoic Acids ....................... 421
Pyridinecarboxylic or Picolinic Acids ................ 422
Other ................................................ 423
B Inhibitors of Indoleacetic Acid (IAA) Transport ...... 423
VI. Amino Acid Biosynthesis Inhibitors ...................... 424
A Inhibitors of Acetolactate Synthase (ALS) -
Acetohydroxyacid Synthase (AHAS) ..................... 424
Sulfonylureas ........................................ 424
Imidazolinones ....................................... 426
Pyrimidinylthio-Benzoate ............................. 426
Sulfonylamino-Carbonyltriazolmone .................... 426
Triazolopyrimidines .................................. 427
B Inhibitors of 5-Enolpyruvyl-Shikimate-3-Phosphate
Synthase (EPSP) ...................................... 427
C Inhibitors of Glutamine Synthetase (GS) .............. 428
VII. Inhibitors of Respiration ............................... 428
A. Uncouplers of Oxidative Phosphorylation .............. 429
Arsenites ............................................ 429
Phenols .............................................. 429
VIII. Unknown Mechanism of Action ............................. 430
IX. Summary ................................................. 432
Things to Think About ................................... 434
Literature Cited ........................................ 434
Chapter 14 Herbicides and Plants ............................. 437
I. Factors Affecting Herbicide Performance ................. 438
II. General ................................................. 438
A. Sprayer Calibration .................................. 438
B. Reaching the Target Plant ............................ 441
Drift ................................................ 441
Volatility ........................................... 444
III. Foliar Active Herbicides ................................ 445
A. Spray Retention ...................................... 445
Leaf Properties ...................................... 446
Other Factors ........................................ 448
Characteristics of Spray Solution .................... 448
B. Environmental Factors ................................ 449
Moisture ............................................. 449
Temperature .......................................... 450
Light ................................................ 451
IV. Physiology of Herbicides in Plants ...................... 451
A Foliar Absorption .................................... 451
Stomatal Penetration ................................. 452
Cuticular Penetration ................................ 452
Fate of Foliar Herbicides ............................ 452
Advantages and Disadvantages of Foliar Herbicides .... 453
B Absorption from Soil ................................. 453
General .............................................. 453
Advantages and Disadvantages of Soil-Applied
Herbicides ........................................... 454
Root Absorption ...................................... 454
Influence of Soil pH ................................. 454
C Shoot Versus Root Absorption ......................... 455
D Absorption as a Determinant of Selectivity ........... 456
E Translocation ........................................ 458
F Translocation as a Determinant of Selectivity ........ 458
G Herbicide Metabolism in Plants ....................... 460
H Metabolism as a Determinant of Selectivity ........... 462
Things to Think About ................................ 466
Literature Cited ..................................... 467
Chapter 15 Herbicides and Soil ............................... 469
I. Soil .................................................... 470
II. Factors Affecting Soil-Applied Herbicides ............... 473
A Physical Factors ..................................... 473
Placement ............................................ 474
Time of Application .................................. 474
Volatility ........................................... 474
Adsorption ........................................... 475
Leaching ............................................. 477
Interactions with Soil Moisture ...................... 478
B Chemical Factors ..................................... 480
Microbial or Enzymatic Degradation ................... 480
Chemical or Nonenzymatic Degradation ................. 481
Photodegradation ..................................... 482
III. Soil Persistence of Herbicides .......................... 482
Things to Think About ................................... 486
Literature Cited ........................................ 486
Chapter 16 Herbicide Formulation ............................. 489
I. Introduction ............................................ 489
II. Types of Herbicide Formulation .......................... 492
A Liquid Formulations .................................. 492
Solution Concentrate ................................. 492
Emulsifiable Concentrate ............................. 493
Invert Emulsions ..................................... 494
Flowable Concentrate ................................. 494
Encapsulated ......................................... 495
B Dry Formulations ..................................... 495
Dusts and Dry Powders ................................ 495
Wettable Powders ..................................... 495
Granules ............................................. 496
Dry Flowable and Water Dispersible Granules .......... 496
Water-Soluble Packets and Effervescent Tablets ....... 497
Other ................................................ 497
III. Surfactants and Adjuvants ............................... 498
Things to Think About ................................... 498
Literature Cited ........................................ 498
Chapter 17 Herbicides and the Environment .................... 501
I. Herbicide Performance ................................... 502
II. Ecological Changes ...................................... 504
A Effects of Herbicide Use ............................. 504
B Herbicide Resistance ................................. 507
A Enhanced Soil Degradation ............................ 508
D Influence of Herbicides on Soil ...................... 508
E Herbicide-Disease Interactions ....................... 509
III. Environmental Contamination ............................. 511
A Effects on Water ..................................... 511
B Human Effects ........................................ 512
General .............................................. 512
The Case of Flourides ................................ 515
2,4,5-T .............................................. 516
Summary .............................................. 517
C Global Change ........................................ 519
IV. Energy Relationships .................................... 520
V. Herbicide Safety ........................................ 524
A. Perception of Risk ................................... 524
Б. Rules for Safe Use of Herbicides ..................... 527
C. The LD50 of Some Herbicides .......................... 528
Things to Think About ................................ 532
Literature Cited ..................................... 533
Supplementary Literature ............................. 534
Chapter 18 Pesticide Legislation and Registration ............ 537
I. The Principles of Pesticide Registration ................ 537
II. Federal Laws ............................................ 539
III. Federal Insecticide, Fungicide, and Rodenticide Act ..... 540
A. Amendments ........................................... 541
IV. The Environmental Protection Agency (EPA) ............... 543
V. Federal Environmental Pesticide Control Act ............. 544
VI. Procedural Summary ...................................... 545
VII. Tolerance Classes ....................................... 547
A Exempt ............................................... 547
B Zero ................................................. 547
C Finite ............................................... 548
D Nonfood Crop Registration ............................ 548
VIII. The Procedures for Pesticide Registration ............... 548
Things to Think About ................................... 552
Literature Cited ........................................ 552
Chapter 19 Weed Management Systems ........................... 553
I. Introduction ............................................ 553
II. A Metaphor for Weed Management .......................... 556
III. The Logical Steps of Weed Management .................... 557
A Prevention ........................................... 557
B Mapping .............................................. 558
C Prioritization ....................................... 558
D Development of an Integrated Weed Management
System ............................................... 559
E Implementation of Systematic Weed Management ......... 561
F Record Keeping and Evaluation ........................ 562
G Persistence .......................................... 562
IV. Weed Management Principles in Six Systems ............... 563
A Small Grain Crops .................................... 564
Prevention ........................................... 564
Mechanical Methods ................................... 565
Cultural ............................................. 566
Biological ........................................... 568
Chemical ............................................. 568
B Corn and Row Crops ................................... 569
Prevention ........................................... 570
Mechanical ........................................... 570
Cultural ............................................. 571
Biological ........................................... 572
Chemical ............................................. 572
Integrated Strategies ................................ 573
C Turf ................................................. 574
D Pastures and Rangeland ............................... 576
E Perennial Crops ...................................... 578
Prevention ........................................... 579
Cultural ............................................. 579
Mechanical ........................................... 580
Chemical ............................................. 580
F Aquatic Weed Sites ................................... 581
Classification of Weeds .............................. 581
Prevention ........................................... 581
Mechanical ........................................... 583
Biological ........................................... 584
Chemical ............................................. 585
G Woody Plants ......................................... 585
V. Molecular Biology in Weed Management .................... 586
VI. Weed Management Decision Aids ........................... 588
VII. Summary ................................................. 593
Things to Think About ................................... 593
Literature Cited ........................................ 594
Chapter 20 Weed Science - The Future ......................... 599
I. Research Needs .......................................... 600
A Weed Biology ......................................... 601
Weed Biology and Seed Dormancy ....................... 601
Weed-Crop Competition and Weed Ecology ............... 602
B Allelopathy .......................................... 604
C Biological Control ................................... 604
D Weed Control and Bioeconomic Models .................. 605
E Bioeconomic Models ................................... 606
F Herbicide Technology ................................. 606
Study of Plant Biochemistry and Physiology ........... 608
Rate Reduction and Precise Application ............... 609
Soil Persistence and Controlled Soil Life ............ 609
Formulation Research ................................. 609
Perennial Weeds ...................................... 610
Aquatic Weeds ........................................ 610
Parasitic Weeds ...................................... 610
Packaging and Labeling ............................... 611
The Agricultural Chemical Industry ................... 611
G Biotechnology and Herbicide-Tolerant Crops ........... 613
H Organic Agriculture .................................. 618
I Engineering Research ................................. 619
J Vegetation Management, Integration of Methods, and
Remote Sensing ....................................... 621
K Other Research ....................................... 623
II. Political Considerations ................................ 624
III. Conclusion .............................................. 624
Things to Think About ................................... 626
Literature Cited ........................................ 626
Appendix A
List of Crops and Other Plants Cited in Text .................. 629
Appendix В
List of Weeds Cited in Text ................................... 635
Glossary of Terms Used in Weed Science ........................ 647
Index ......................................................... 655
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