Herbicide Resistance.pptx

The slides describe the concept of Herbicide resistance and explain Herbicide resistance as the inherent ability of a weed to survive treatment with an herbicide that would normally kill it. If a resistant plant is allowed to reproduce, the resistance spreads resulting in more and more plants that are resistant to that particular herbicide. Also some causes, types, examples, and solutions for Herbicide resistance

1. Herbicide Resistance Principle of Weeds Science AGR-506 Presented By: Alhaji Alusine Kebe 19-Arid-4491 6 th semester Agronomy 2022 Assigned by : Dr. M. Ansar 6/16/2022 1

2. Contents Overviews Objective Introduction What is Herbicide Resistance (HR) History Mechanisms of Herbicide Resistance Mode of Action (MOA), and Site of Action (SOA) and Essence in {HR } How does herbicide resistance develop? General principles to manage herbicide resistance Conclusion 6/16/2022 2 Slide No. 3 4 5 7 8 9-13 14 14-15 16-17 18 19 20

3. Overview : This presentation will detail the essential mechanisms and heredities of herbicide-resistance in weeds. Herbicide resistance is a major issue in weed science today; therefore, it is important to have a basic understanding of the process by which it occurs. The management and spread of herbicide-resistant weeds in relationship to the biochemical mechanisms and inheritance of resistance will be explained. Resistance based on types of resistance will be described. 6/16/2022 3

4. Objectives : The objective of this presentation is: Understand the development of herbicide-resistance. Describe how and why herbicide resistance occurs based on the genetic involvement. Explain the difference between target-site based resistance, metabolism-based resistance, and other types of resistance. Understand the difference between Site of Action and mode of Action. 6/16/2022 4

5. The introduction of synthetic herbicides revolutionized weed control. However , the repeated use of herbicides led to the evolution of herbicide-resistant in weed populations. Herbicide resistant weeds are one of the major challenges in weed management. The selection of resistant weeds reduces control options and may increase control costs and other environmental problems. In many cases, the most effective and economical herbicide is lost because it is no longer effective due to resistant weeds . Introduction 6/16/2022 5

6. Herbicides kill plants by interrupting the normal growth of the plant. Herbicides usually bind to a molecular target site, often a protein, in the plant. Once the herbicide binds, biochemical or physiological processes in the plant are inhibited and the plant dies. Herbicide-resistant plants possess at least one mechanism that allows them to survive from herbicide treatment. Introduction 6/16/2022 6

7. What is Herbicide Resistance (HR) Herbicide resistance is the naturally occurring, inheritable ability of some weed biotypes within a given weed population to survive from herbicide treatment that should otherwise, effectively control the weed population. 6/16/2022 7

8. History The first herbicide resistant weed Senecio vulgaris L(common names groundsel and old-man-in-the-spring)., was identified in 1968 in a nursery in Washington State. To date, 261 different herbicide-resistant biotypes have been identified . In some instances, the same species has been identified with resistance to different herbicides in different locations. Resistance has occurred to most herbicide chemical families. 6/16/2022 8

9. Mechanisms of Herbicide Resistance For a herbicide to reach its active site in the plant, it must be taken into the plant and moved in lethal concentrations to the site where it has activity will initiate. Once it reaches the target site, it must be able to bind to the active site and stop that particular pathway. For a plant to be resistant, there must be a change that will allow it to avoid one or more of these steps. Theoretically, there could be a change in any one of these necessary steps beginning with uptake of the herbicide into the plant. 6/16/2022 9

10. Potential mechanisms that could be responsible for resistance: Target-site mutation there is a change in the binding site that prevents the herbicide from binding or interacting. Reduced uptake the herbicide is not taken up in lethal quantities. Reduced translocation the herbicide is not transported to the site in the plant where it has activity. Sequestration the herbicide is physically removed from the target site. Metabolism the herbicide is modified into a nontoxic molecule before it reaches the target site . 6/16/2022 10

11. Altered target site or Target-site mutation An herbicide has a specific site (target site of action) where it acts to disrupt a particular plant process or function (mode of action ). If this target site is somewhat altered, the herbicide no longer binds to the site of action and is unable to exert its phytotoxic effect. This is the most common mechanism of herbicide resistance. 6/16/2022 11

12. Enhanced metabolism : Metabolism within the plant is one mechanism a plant uses to detoxify a foreign compound such as an herbicide. A weed with the ability to quickly degrade an herbicide can potentially inactivate it before it reaches its site of action within the plant. 6/16/2022 12

13. compartmentalization or sequestration Some plants can restrict the movement of foreign compounds (herbicides) within their cells or tissues to prevent the compounds from causing harmful effects . In this case, an herbicide may be inactivated either through binding (such as to a plant sugar molecule) or removed from metabolically active regions of the cell to inactive regions, the cell wall, for example, where it exerts no effect. 6/16/2022 13

14. Mode Of Action (MOA), And Site Of Action (SOA) Mode of Action (MOA ) All herbicide interactions with the plant, from application to final effect, are considered the mode of action. The mode of action involves absorption into the plant, translocation or movement in the plant, metabolism of the herbicide, and the physiological plant response. Site of Action (SOA ) Herbicide Site of Action is the specific process in plants that the herbicide disrupts to interfere with plant growth and development. The SOA is the most important aspect of herbicides when dealing with prevention and control of herbicide resistant weeds. 6/16/2022 14

15. 6/16/2022 15 Mode of Action (MOA) Site of Action (SOA) Product Examples Light dependent herbicide Photosynthesis Inhibitors Inhibit of pigment production Cell membrane disrupter and inhibitor Glyphosate, Bentazon, Metribuzin Fatty acid biosynthesis inhibitor Lipid Synthesis Inhibitors Inhibitor of acetyl CO enzyme Inhibitor of biosynthesis of very long chain of fatty acid fenoxaprop (Whip/Acclaim) Poast, Select Max Cell growth inhibitor Inhibitor of micropule assembly Inhibitor of mitosis Inhibitor of cell wall synthesis Aim, Valor , Sharpen Gramoxone SL Amino Acid Synthesis Inhibitors Inhibitor of aceto-lactat synthase Inhibitor of 5-etnol pyruvate synthase Inhibitor of glutamine synthase Ally, Everest, Pursuit Roundup, Touchdown 15

16. 6/16/2022 16 Growth Regulators (Auxin like action) Synthesis of auxin Mineral of IAA Clarity, Starane, 2,4D component of Status Nitrogen Metabolism Inhibitors 10-Glutamine Synthetase Inhibitor Liberty, Cheeta Seedling Root/ Shoot Growth Inhibitors 3-Microtubule Inhibitors Prowl H20, Treflan Bolero, Far-Go Harness, Duel Magnum, Zidua Norton Inhibitors of respiration Un-coupler of oxidized popoxylation Sonar Command Callisto , Laudis Undefined MSMA

17. How does herbicide resistance develop? A small number of plants in any weed population are naturally resistant to a given herbicide. A repeated application of this herbicide alone will thus lead to a selection of these plants. The result : over a period of several such “selections” the resistant biotype can dominate the complete weed population. 6/16/2022 17

18. Development of herbicide resistance in a weed population Normal population After continued selection pressure Resistant population 6/16/2022 18

19. General principles to manage herbicide resistance Apply integrated weed management practices that include both chemical and non chemical practices such as cultural, biological and mechanical measures in context with the cropping system. Use herbicide mixtures, sequences, or rotations with overlapping weed spectra and multiple, distinct sites-of-action (SOA). Use the full-recommended herbicide rate and the proper application timing. Scout fields after herbicide application to ensure control has been achieved. Prevent weeds that escape control from producing seed. Monitor site and clean equipment between sites . 6/16/2022 19

20. Conclusion Herbicide resistance will continue to be a weed management problem as long as herbicides are used for weed control. Repeated use of a herbicide increases the risk that a resistant biotype will be selected. The major mechanisms for resistance are either a change in the herbicide's target-site or increased herbicide metabolism . For annual cropping situations, also consider the following: Start with fields free of weeds and control weeds early by using a treatment or tillage in combination with a pre-emergence residual herbicide. Use cultural and mechanical practices such as crop rotation, cover crops, intercropping, choice of competitive cultivars, seeding time, and tillage as appropriate and fit. Use good agronomic principles that have positive effects on crop competitiveness and yield by negatively affecting weed flora and weed development. 6/16/2022 20

21. Vote Of Thanks Suggestion / questions Thank you for your Keen attention 6/16/2022 21