Saeed vali rasti professor Karimmojeni 95-96

Reducing the Risks of Herbicide Resistance: Best Management Practices and Recommendations کاهش خطرات ناشی از مقاومت به علف‌کش‌ها : بهترین توصیه‌ها و شیوه‌های مدیریت

Why control weeds? To reduce competition for light, moisture, and nutrients

Weeds reduce yield and quality Weeds produce leachates (allelochemicals) that may be detrimental to the crop

Weeds serve as hosts for diseases and insects Weeds increase production and processing costs Weeds decrease land value and crop choice Weeds are human hazards and aesthetically unpleasing

Management practices Non herbicide methods Mechan ical physicalCultural Biological Herbicide methods RotationsSequentialMixtures prevention Resistance Management

Prevention is the best method

Methods of weed control Mechanical/physical Hand-pulling, hand-hoeing, tillage, mowing, flooding, mulching, burning

Cultural Crop competition, crop rotation, crop varieties, fertility manipulation, planting date, plant population and spacing

Biological Insects, pathogens, herbivores Chemical Herbicides Preplant, preemergence, postemergence

Best Management Practices ) BMPs ( BMP 1: Understand the Biology of the Weeds Present. Germination Requirements and Emergence Pattern. Reproductive Biology and Life Cycle. Duration of Reproductive Development. Mode of Dispersal. Persistence in Soil Seedbank.

BMP 2: Use a Diversified Approach to Weed Management Focused on Reducing Weed Seed Production and the Number of Weed Seeds in the Soil Seedbank. BMP 3: Plant into Weed-Free Fields and Keep Fields as Weed Free as Possible.

BMP 4: Plant Weed-Free Crop Seed. BMP 5: Scout Fields Routinely.

BMP 6: Use Multiple, Effective MOAs against the Most Troublesome Weeds and Those Prone to Herbicide Resistance. Rotations, Sequential Applications, and Mixtures to Mitigate Resistance. Using Rotations and Mixtures After Resistance Has Evolved. Rotating Crops with Different or Multiple Herbicide-Resistance Traits. BMP 7: Apply the Labeled Herbicide Rate at Recommended Weed Sizes.

BMP 8: Emphasize Cultural Management Techniques that Suppress Weeds by Using Crop Competitiveness. Cultivar Selection. Planting Date

Narrow Rows and Seeding Rates. Crop Rotation. Nutrient Management. Irrigation Management

BMP 9: Use Mechanical and Biological Management Practices Where Appropriate. Tillage. Cover Crops and Synthetic Mulches. Mowing. Grazing. Sheep grazing has been shown to reduce the number of ryegrass plants setting seed by 60 to 80% or 90 to 95% after 3 yr of standard or intense grazing, respectively (Pannell et al. 2004).

BMP 10: Prevent Field-to-field and Within-Field Movement of Weed Seed or Vegetative Propagules. Crop Residues, Manures, and Plant By-Products. BMP 11: Manage Weed Seed at Harvest and Postharvest to Prevent a Buildup of the Weed Seedbank. At Harvest. After Harvest. BMP 12: Prevent an Influx of Weeds into the Field by Managing Field Borders.

Transgenic plants

The area under biotech crops in the world in 2008

GM canola surrounded by weeds - glyphosate+ glyphosate

Integrated weed management (IWM)

Recommendations for Adoption of BMPs Recommendation One: Reduce the Weed Seedbank through Diversified Programs that Minimize Weed Seed Production. Recommendation Two: Implement a Herbicide-MOA Labeling System for All Herbicide Products, and Conduct an Awareness Campaign. Recommendation Three: Communicate that Discovery of New, Highly Effective Herbicide MOAs Is Rare and that the Existing Herbicide Resource Is Exhaustible.

Recommendation Four: Demonstrate the Benefits and Costs of Proactive, Diversified Weed Management Systems for the Mitigation of HR Weeds. Recommendation Five: Foster the Development of Incentives by Government Agencies and Industry that Conserve Critical Herbicide MOAs as a Means to Encourage Adoption of Best Practices. Recommendation Six: Promote the Application of Full, Labeled Rates at the Appropriate Weed and Crop Growth Stage.

Recommendation Seven: Identify and Promote Individual BMPs that Fit Specific Farming Segments with the Greatest Potential Impact. Recommendation Eight: Engage the Public and Private Sectors in the Promotion of BMPs, Including Those Concerning Appropriate Herbicide Use. Recommendation Nine: Direct Federal, State, and Industry Funding to Research Addressing the Substantial Knowledge Gaps in BMPs for Herbicide Resistance and Support Cooperative Extension Services as Vital Agents in Education for Resistance Management.

References K.Jason. Norsworthy, Sarah M. Ward, David R. Shaw, Rick S. Llewellyn, Robert L. Nichols, Theodore M. Webster, Reducing the Risks of Herbicide Resistance: Best Management Practices and Recommendations. Weed Science. Special Issue:31–62 T. Manaco, Weller. C, 2002, Principles and practices. Weed Science

Thank you for your consideration