logging in or signing up Herbicides aSGuest116411 Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 44 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: October 07, 2011 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide 1: Herbicide Demand When & why?Slide 2: Herbicide R & D Costs 13 yr to breakeven 7 yrSlide 3: Herbicide R & D Costs 140 mil $USSlide 4: Herbicide Modes of Action Contact vs systemic Acute toxicitySlide 5: Herbicide Modes of Action Inorganic (contact) Ex. Cu2SO4, NH4SO4 Plasmolysis 2. Auxin-like (systemic) Phenoxy-acids: 2,4-D; 2,4,5-T Rapid stem elongation Cells starve 2,4,5-T = agent orange - contam. W/ dioxinSlide 6: 3. Photosynthesis Inhibitors Most target ‘light’ rxnSlide 7: Light-dependent Rxn Atrazine Diquat, paraquat Atrazine inhibits photolysis of waterSlide 9: Ex. Triazines Contact Pre-emergent Corn, soybeans, wheat, blueberries Acute Toxicity Mammals: 1500-3000 ppm Fish: 10-15 ppm Daphnia: 7 ppm Sub-lethal Toxicity Aq. Insect comm. Structure: 20 ppb Algal growth: 1 ppb Aq. Spp richness Rel. AbundanceSlide 10: Atrazine Fate in environment Moderate persistence 7-9 mo. Half-life “dry-year carryover” Surface water 1-70 ppb – rural creeks 1000 ppb – agric. ditches etc.Slide 11: 4. Metabolic Inhibitors Dintrophenols – x electron transport “Round-Up”- Amino Acid Synthesis Inhibitor AA synthesis in plants vs animals 9 “essential” amino acids – dietary only for animals Histidine Isoleucine Leucine Lysine Methionine Threonine Tryptophan Phenylalanine ValineSlide 12: Round-Up (A.I. = glyphosate) Non-selective Post-emergent Low residual activity Water soluble- great systemic Good for rhizomes Phosphophono- amino acidSlide 13: EPSP enzyme Aromatic a.a. Glyphosate ‘kills’ EPSP enzyme; so no aromatic a.a. Not toxic to animals?Slide 14: Glyphosate Toxicity to Plants Primary: Slow, 3 weeks+ Depletes aromatic a.a. no protein synthesis NH3+ accumulates (toxic) Secondary: Aromatic a.a. sustain auxin So- glyphosate speeds auxin breakdown More lateral growth Shallow root “tillering”Slide 15: Herbicide Resistant Crops How? Insert constitutive EPSP gene Examples “Round-up Ready” Corn & Soybeans Pros & Cons Others: insect resistant crops (StarLink corn- Bt genes) You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.