Slide Presentation

TITLE    (click title to view slides)
Herbicide Modes of Action

AUTHOR
Eric P. Prostko
Extension Weed Specialist
Department of Crop and Soil Sciences
The University of Georgia

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TABLE OF CONTENTS
  1. Herbicide Modes of Action
  2. Some things to remember...
  3. Mode of Action
  4. Mechanism of Action (Site)
  5. ACCase Inhibitors
  6. Rotted meristem
  7. ALS Inhibitors
  8. Commonly Used ALS Herbicides
  9. Cadre 'yellow flash'; Staple+ on Sorghum
  10. Resolve 25WG (rimsulfuron) Injury to Field Corn
  11. Photosystem II Inhibitors
  12. Bladex; Cotoran
  13. Photosystem I Inhibitors
  14. Paraquat
  15. PPO Inhibiting Herbicides
  16. Blazer Injury on Peanut; Valor Injury on Peanut; Cobra on Soybeans
  17. Carotenoid Biosynthesis Inhibitors
  18. Command; Zorial; Laudis
  19. EPSP Synthase Inhibitor
  20. Injury
  21. Glutamine Synthetase Inhibitors
  22. Injury
  23. Mitosis Inhibitors
  24. Prowl Injury on Corn
  25. Dual Injury
  26. Fatty Acid and Lipid Biosynthesis Inhibitors
  27. Injury
  28. Synthetic Auxins
  29. Injury
  30. Unknown MOA
  31. MSMA on Peanut and Zoysia
  32. UGA Weed Science



SLIDE CONTENTS
  1. Herbicide Modes of Action Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia April 2008
  2. Some things to remember…. photosynthesis (food) respiration (energy) amino acids (proteins/growth) lipids (cell membranes) pigments (energy/light capture) chlorophyll, carotenoids mitosis (cell division)
  3. Mode of Action the sequence of events that leads to plant death or growth interruption 2 phases * movement to target site * interaction at target site
  4. Mechanism of Action (Site) Location at which a herbicide exerts its toxicity at the cellular level more specific
  5. ACCase Inhibitors Inhibit acetyl-CoA-carboxylase (ACCase) enzyme Enzyme needed for fatty acid synthesis Dim’s and Fop’s Achieve, Assure, Axial, Fusilade, Poast, Select
  6. Source: W. K. Vencill, UGA “rotted” meristem
  7. ALS Inhibitors Inhibit acetolactate synthase (ALS) enzyme enzyme needed to produce certain amino acids (isoleucine, leucine, valine)
  8. Commonly Used ALS Herbicides Accent Ally/Cimarron Beacon Beyond Cadre Classic Envoke Exceed Express Finesse FirstRate Glean Harmony Extra Maverick Pro Osprey Peak Permit Pursuit Python Scepter Staple Strongarm
  9. Cadre “yellow flash” Staple+ on Sorghum
  10. Resolve 25WG (rimsulfuron) Injury to Field Corn Pictures @ 18 DAT 1.0 oz/A Applied PRE
  11. Photosystem II Inhibitors Inhibit photosynthesis by binding to QB-binding niche on D1 protein Evik, Caparol, Atrazine, Basagran, Buctril, Direx, Cotoron, Lorox, Sencor, Simazine
  12. Bladex Cotoran Source: W. K. Vencill, UGA
  13. Photosystem I Inhibitors Accept electrons from PSI to form radicals Super radicals formed to create peroxides Diquat, paraquat
  14. Paraquat Source: Purdue University
  15. PPO Inhibiting Herbicides PPO or Protox Protoporphyrinogen oxidase Enzyme found in chloroplast and mitochondria needed for formation of chlorophyll Cell membrane destruction Many common herbicides have this mode of action!! Ultra Blazer, Cobra, Goal, Reflex, Ronstar, Resource, Aim, Valor, Storm, Spartan, ET
  16. Blazer Injury on Peanut Valor Injury on Peanut Cobra on Soybeans
  17. Carotenoid Biosynthesis Inhibitors Inhibit phytoene desaturase (PDS) or hydroxyphenyl pyruvate dioxygenase (HPPD) Command, Callisto, Laudis, Solicam/Zorial, Impact
  18. Command Zorial Laudis
  19. EPSP Synthase Inhibitor EPSP synthase needed for production of certain amino acids (tryptophan, tyrosine, and phenylalanine) glyphosate
  20. Source: Purdue University Weed Science Source: MSU Weed Science
  21. Glutamine Synthetase Inhibitors Glutamine synthetase converts glutamate and ammonia to glutamine Causes ammonia accumulation in plants Liberty, Ignite
  22. Source: University of Missouri Weed Science
  23. Mitosis Inhibitors Microtubule inhibition Treflan, Prowl, Sonalan, Surflan, Dacthal Inhibition of very long-chain fatty acids Dual Magnum, Outlook, Intrro
  24. Prowl Injury on Corn
  25. Source: University of Wisconsin Weed Science Dual Injury
  26. Fatty Acid and Lipid Biosynthesis Inhibitors Inhibition of lipid synthesis (not ACCase) Prefar, Sutan, Eptam, Eradicane, Ordram, Tillam, Bolero
  27. Source: Purdue University Weed Science Source: UC-Davis Weed Science
  28. Synthetic Auxins Disrupt hormonal balance 2,4-D, Banvel, Clarity, Status, Stinger, MCPA, Facet, Remedy, Grazon P+D
  29. Source: Purdue University Weed Science Source: Purdue University Weed Science
  30. Unknown MOA DSMA, MSMA Cell membrane destruction???
  31. MSMA on Peanut MSMA on Zoysia
  32. UGA Weed Science www.gaweed.com