“Herbicides and Their Mechanisms of Action” Integrated Pest Management & Certification Training Richard D.
Download ReportTranscript “Herbicides and Their Mechanisms of Action” Integrated Pest Management & Certification Training Richard D.
“Herbicides and Their Mechanisms of Action” Integrated Pest Management & Certification Training Richard D. Lee IPM Specialist USDI-BLM Journey in Time 20 companies 1984: Cyanamid Miles Dow Stauffer ICI Americas Monsanto Union Carbide Rohm & Haas Zoecon FMC BASF Eli Lilly DuPont Shell CIBA-Geigy Nor-AM Hoechst Velsicol ISK Biotech Ortho Journey in Time Early 2002: Syngenta Bayer BASF Dow AgroSciences DuPont Valent Monsanto FMC 8 companies Active Ingredients Approved for Use on BLM Atrazine Bromacil Chlorsulfuron Clopyralid 2,4-D Dicamba Diuron Fosamine Ammonium Glyphosate Hexazinone AAtrex Nine-O Hyvar ® Telar ® Transline ® various Clarity ® Vanquish ® Karmex ® Krenite ® Roundup Pro ® AquaMaster ® Velpar L ® ® Syngenta DuPont DuPont Dow AgroSci. several BASF Syngenta Griffin DuPont Monsanto Monsanto DuPont Active Ingredients Approved for Use on BLM Imazapyr Imazapic Mefluidide Metsulfuron methyl Picloram Simazine Sulfometuron methyl Tebuthiuron Triclopyr Arsenal ® Plateau ® Embark ® BASF BASF PBI Gordon Escort XP ® Tordon 22K ® Princep ® DuPont Dow AgroSci. Syngenta Oust XP ® Spike 20P ® Garlon 3A, 4 DuPont Dow AgroSci. Dow AgroSci. ® Classification of Herbicides Application Method Foliar Applied • Plant contact Soil Applied • Soil contact Broadcast • Entire area Spot • Specified area Classification of Herbicides Application Timing Preemergence • Prior to seed germination Postemergence • After seed germination and active growth Post-directed • Directed to particular portion of plant once emerged and growing Classification of Herbicides Plant/Soil Environment Selectivity • Selective vs nonselective Systemic • Mobile vs nonmobile in the plant Residual Activity • Extended vs nonextended soil activity Classification of Herbicides Formulation Liquid • Solution • Emulsifiable conc. • Flowable Dry • • • • Soluble powder Wettable powder Dry flowable Granular Classification of Herbicides Mechanism of Activity “Why You See What You See When You See” Focus of the discussion Lets take some time discussing how herbicides kill their target and what it looks like. What To Do If Herbicide Injury is Suspected. 1. Seek background information. History of the area. 2. Evaluate what is seen. Look at the roots. Loot at the stems. Look at the leaves. Consider all possible options or situations. What To Do If Herbicide Injury is Suspected. Identify possible source. Off-target movement. Wrong herbicide. Improper Application. Other options/ideas??? Herbicide Behavior in Plants To understand herbicide injury we need to understand the ways in which herbicides do their job. Remember!!!! “Herbicide injury, in most cases, is the result of the herbicide, doing what it was designed to do, in the wrong place at the wrong time.” Active Ingredients Approved for Use on BLM Atrazine Bromacil Chlorsulfuron Clopyralid 2,4-D Dicamba Diuron Fosamine Ammonium Glyphosate Hexazinone AAtrex Nine-O Hyvar ® Telar ® Transline ® various Clarity ® Vanquish ® Karmex ® Krenite ® Roundup Pro ® AquaMaster ® Velpar L ® ® Syngenta DuPont DuPont Dow AgroSci. several BASF Syngenta Griffin DuPont Monsanto Monsanto DuPont Active Ingredients Approved for Use on BLM Imazapyr Imazapic Mefluidide Metsulfuron methyl Picloram Simazine Sulfometuron methyl Tebuthiuron Triclopyr Arsenal ® Plateau ® Embark ® BASF BASF PBI Gordon Escort XP ® Tordon 22K ® Princep ® DuPont Dow AgroSci. Syngenta Oust XP ® Spike 20P ® Garlon 3A, 4 DuPont Dow AgroSci. Dow AgroSci. ® Types of Herbicide Injury 1. 2. 3. 4. 5. 6. 7. 8. Plant Growth Regulation Photosynthesis Inhibitors Photosynthetic Pigment Inhibitors Plant Growth Inhibitors Amino Acid Synthesis Inhibition Lipid Biosynthesis Inhibition Cell Membrane Disruption Unclassified Activity Active Ingredients Approved for Use on BLM Atrazine Bromacil Chlorsulfuron Clopyralid 2,4-D Dicamba Diuron Fosamine Ammonium Glyphosate Hexazinone Photosynthetic Inhibitor Photosynthetic Inhibitor Amino Acid Biosynthesis Plant Growth Regulator Plant Growth Regulator Plant Growth Regulator Photosynthetic Inhibitor Plant Growth Regulator Amino Acid Biosynthesis Photosynthetic Inhibitor Active Ingredients Approved for Use on BLM Imazapyr Imazapic Mefluidide Metsulfuron methyl Picloram Simazine Sulfometuron methyl Tebuthiuron Triclopyr Amino Acid Biosynthesis Amino Acid Biosynthesis Plant Growth Regulator Amino Acid Biosynthesis Plant Growth Regulator Photosynthetic Inhibitor Amino Acid Biosynthesis Photosynthetic Inhibitor Plant Growth Regulator Types of Herbicide Injury 1. 2. 3. 4. 5. 6. 7. 8. Plant Growth Regulation Photosynthesis Inhibitors Photosynthetic Pigment Inhibitors Plant Growth Inhibitors Amino Acid Synthesis Inhibition Lipid Biosynthesis Inhibition Cell Membrane Disruption Unclassified Activity Mechanism of Action & Herbicides Used Plant Growth Regulating Herbicides Plant Growth Regulation Activity is similar to that of IAA. Addition of “synthetic IAA” results in an imbalance of the growth regulating hormone. Cells of the leaf vein rapidly divide while cells between the veins do not. Cell division and respiration increase, while photosynthesis does not. Plant Growth Regulation What are you going to see visually? 1. Strap-like leaves - parallel veins in the leaves. 2. Downward twisting and cupping of the leaves. 3. Excessive adventitious root formation will be stimulated upon root contact. Plant Growth Regulation Inter-venal Cells Do Not Divide Leaf Vein Cell Divide Plant Growth Regulation Examples include: 2,4-D Dicamba Picloram Clopyralid Triclopyr How does this type of injury occur? Drift - both particle and vapor. Improper cleaning of equipment. Applying when air temperatures exceed those listed on the label. Exceeding the labelled rate. Mechanism of Action & Herbicides Used Photosynthetic Inhibiting Herbicides Photosynthesis Inhibitors The photosynthetic process is shut down. Generally applied to the soil, moves through the plant in the xylem system. Foliage and stems are affected, yet the root system is not. Photosynthesis Inhibitors Plants exposed to treated soil will germinate and emerge, take up the herbicide and move it to the leaves where it will result in injury. Photosynthesis Inhibitors What are you going to see visually? 1. Plants turn yellow and die as a result of chlorophyll breakdown. 2. As the injury proceeds, the plant will turn brown and die from the bottom of the plant to the top of the plant. 3. Leaves initially turn yellow between the veins, dying from the tip towards the base, and from the outer edge to the center. Photosynthesis Inhibitors Examples Include: Atrazine Bromacil Diuron Hexazinone Simazine Tebuthiuron How does this type of injury occur? Movement of treated soil - these herbicides are residual. Lack of incorporation into the soil. Applying in an area where the root system of desirable plants can take up the herbicide. NOT READING THE LABEL. Failing to understand the residual capability of these herbicides. Mechanism of Action & Herbicides Used Amino Acid Synthesis Inhibiting Herbicides Amino Acid Synthesis Inhibition Injury is associated with a particular enzyme, which, in turn, is associated with a particular amino acid process. Visual results are the result of secondary injury – the injury as the beginning of a chain of events that take place in the plant. This is why the visual symptoms take time to develop – it is not an immediate process. Amino Acid Synthesis Inhibition Amino Acid Synthesis Inhibition May or may not have soil activity. Activity associated with a particular amino acid synthesis sequence. Acetyl CoA Carboxylase (ACCase) - Select Acetolacte Synthase (ALS) - Arsenal, Escort EPSPase Inhibitor - Roundup Interference is translated to protein synthesis and inhibition of growth which takes time - slow acting. Amino Acid Synthesis Inhibition What are you going to see visually? Initially there will be a general yellowing of the treated plants. After 5 to 10 days, chlorosis results in necrosis. Amino Acid Synthesis Inhibition Imidazolinones Arsenal Plateau Sahara Top Site Glyphosate Roundup Sulfonylureas Escort Oust Telar How does this type of injury occur? Drift - application on a windy day. Movement of treated soil. Failure to apply the correct amount – the use rates are small and an error in measuring can make a large difference. Summary Ideas By taking time to learn about the visual symptoms associated with the different classes of herbicides you can more easily understand what you see, when you see it. Summary Just Remember: “Worrying has killed more people than work because more people worry than work.”