Implementing Integrated Weed Management for Herbicide Tolerant Crops Implementing Integrated Weed Management for Herbicide Tolerant Crops Table of Contents ACKNOWLEDGEMENTS . .3 TERMINOLOGY . .3 1. EXECUTIVE SUMMARY . .5 2. INTRODUCTION . .6 2.1. Stewardship . .6 2.2. Herbicide tolerant crops . .7 2.3. Integrated weed management . .7 3. BACKGROUND ON WEEDS AND HERBICIDES . .8 3.1. Weeds . .8 3.1.1. Types of weeds . .9 3.1.2. Impact of weeds on crop production . .9 3.2. Herbicides . .10 3.2.1. Herbicide development . .10 3.2.2. Herbicide mechanism of action . .11 3.2.3. Herbicide selectivity . .13 3.3. Herbicide Resistant Weeds . .13 3.3.1. Origins of resistance . .14 3.3.2. Mechanisms of resistance . .14 3.3.3. Current status of resistant weeds globally . .14 3.4. Developing Herbicide Tolerant Crops . .15 3.4.1. Conventional herbicide tolerant crops . .15 3.4.2. Biotech-derived herbicide tolerant crops . .16 4. TOOLS FOR INTEGRATED WEED MANAGEMENT . .17 4.1. Preventing the spread of weeds . .17 4.2. Monitoring weed populations . .18 4.3. Cultural controls . .18 4.3.1. Crop rotations . .18 4.3.2. Crop management . .18 4.3.3. Tillage systems . .20 4.3.4. Mowing . .22 4.3.5. Burning . .22 4.3.6. Allelopathy . .22 4.4. Biological controls . .22 4.5. Herbicides . .23 4.5.1. Herbicide tolerance . .23 1 5. HERBICIDE TOLERANT CROPS . .24 5.1. History of herbicide tolerant crops . .24 5.2. Conventional herbicide tolerant crops . .24 5.2.1. Imidazolinone tolerance . .25 5.2.2. Cyclohexanedione tolerance . .25 5.3. Biotech-derived herbicide tolerant crops . .25 5.3.1. Glyphosate tolerance . .25 5.3.2. Glufosinate tolerance . .26 5.3.3. Bromoxynil tolerance . .26 5.3.4. Sulphonylurea tolerance . .26 5.4. Conventional vs. biotech-derived herbicide tolerant crops . .27 5.4.1. Pros and cons of conventional herbicide tolerant crops . .27 5.4.2. Benefits of herbicide tolerant crops . .27 5.4.3. Concerns about herbicide tolerant crops . .29 5.4.4. Conclusions . .35 6. DEVELOPING AN INTEGRATED WEED MANAGEMENT PLAN . .36 6.1. Purpose . .37 6.2. Weed management areas . .37 6.3. Problem weeds . .37 6.4. Effectiveness of control measures . .37 6.5. Planned crop rotations . .37 6.6. Control strategies and resources . .37 6.7. Weed management plans . .37 6.8. Implementation . .37 6.9. Review and revision . .38 6.10. Importance of keeping accurate records . .38 7. REFERENCES . .39 Appendix 1. INFORMATION ON HERBICIDES . .44 A1. Classification of Herbicides . .44 A2. Factors contributing to resistance susceptibility . .47 Appendix 2. EXAMPLES OF IWM LOCAL AND REGIONAL PROGRAMMES . .50 Appendix 3. SAMPLE SOP FOR IMPLEMENTING INTEGRATED WEED MANAGEMENT . .51 Appendix 4. RECORD OF INTEGRATED WEED MANAGEMENT AND MAP . .55 Appendix 5. RECORD OF WEED MONITORING . .56 Appendix 6. RECORD OF IWM MODIFICATION . ..