lecture 14n15

lecture 14n15 - 3/16/11 Herbicide Mode of Ac1ons...

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Unformatted text preview: 3/16/11 Herbicide Mode of Ac1ons Botany 304 Mode of Ac)ons 1.  Growth Regulator Herbicides 2.  Amino Acid Inhibitor Herbicides 3.  Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides 4.  Carotenoid Pigment Inhibitor Herbicides 5.  Photosynthe1c Inhibitor Herbicides 6.  Cell Membrane Disrupter Herbicides 7.  Cell Growth Inhibitor Herbicides 1. Growth Regulator Herbicides •  The most obvious effects of these herbicides on suscep1ble plants are twis1ng and downward curvature (epinesty) of stems and leaves soon aTer applica1on. Auxin herbicide formula1ons are primarily: –  Salts of the acid –  Low ­vola1le esters. •  Subject to long distant driT damage to non ­target plants. 1 3/16/11 1. Growth Regulator Herbicides Phenoxy Acids •  2,4 ­D  ­ (2,4  ­ dichlorophenoxy) ace1c acid (2,4 ­D) Used in grass crops to control broadleaf weeds •  2,4 ­DB – (2,4 – dichlorophenoxy) butanoic acid –  used in established legumes and soybeans for small weeds like cocklebur, morningglories, and ragweeds. –  Trade Names: Butyrac, Butoxone 1. Growth Regulator Herbicides Benzoic Acids •  Dicamba – 3,6 – dicloro ­2 ­methoxybenzoic acid formulated as potassium or dimethyanime salt –  Used in corn, small grains, pastures, rangelands, turf. Dicamba is not a^racted to soil colloids and is quite mobile in the soil, but with a half ­life of only 14 days, leaching is not a major problem. –  Trade Names: Banvel, Clarity, Dis1nct 1. Growth Regulator Herbicides Picolinic Acids •  Picloram – Tordon •  Clopyralid – S1nger, Reclaim, etc. •  Triclopyr – Garlon, Grandstand, Turflon Ester, etc. •  Most of these herbicides are used for control of woody plants and perennial broadleaf weeds in non ­croplands, rangelands, and individual tree and shrub treatments. 2 3/16/11 2,4 ­D Symptoms 2. Amino Acid Inhibitor Herbicides Amino Acid Deriva)ves * •  Glyphosate – N ­(phosphonomethyl) glycine  ­ Roundup –  All Roundup and related product formula1ons are salts of glyphosate – isopropylamine (IPA), diammonium (NH4), or potassium (K) –  Glyphosate reacts rapidly with and is inac1vated by most soils par1cularly by calcium, iron and aluminum. It degrades in the soil by microbes and leaching is minimal. –  Many weeds are now showing resistance to this herbicide * Prevents forma1on of amino acids (phenylalanine, tyrosine) 3 3/16/11 2. Amino Acid Inhibitor Herbicides Branch ­Chain Amino Acid Inhibitor Herbicides (ALS* Inhibitors) •  Two main groups of chemistries: –  Sulfonylureas (SU’s) –  Imidazolinones (Imi’s) * ALS = Acetolactate Synthase (enzyme) blocks produc1on of branch ­chain amino acids (valine, lucine, isoleucine) 2. Amino Acid Inhibitor Herbicides ALS Inhibitors, Sulfonylureas (SU’s) •  A large group of herbicides mostly used postememgence in grass crops, but a few used preemergence –  Chlorimuron – Classic –  Nicosulfuron – Accent –  Primisulfuron – Beacon 4 3/16/11 2. Amino Acid Inhibitor Herbicides ALS Inhibitors, Sulfonylureas (SU’s) •  Soil pH is a major considera1on when using these compounds since degrada1on is greatly reduced at pH levels of 7.0 or above. Persistence into the next season can limit rota1onal crops due to carryover injury. •  These herbicides can cause an interac1on with some organophosphate insec1cides in injure corn. Used mostly in corn but a few of these products are used in soybeans, turf and other areas. 2. Amino Acid Inhibitor Herbicides ALS Inhibitors, Imidazolinones (Imi’s) •  These herbicides are used both foliar and soil applied primarily in soybeans and other legume crops as well as forest, industrial sites, and prairie restora1on. 2. Amino Acid Inhibitor Herbicides ALS Inhibitors, Imidazolinones (Imi’s) •  Unlike the sulfonylurea herbicides, which are persistent at high pH levels, the imidazolinones persist under low pH, low moisture, and high organic ma^er (OM). –  Imazethapyr – Pursuit –  Imazapyr – Arsenal –  Imazaquin – Scepter 5 3/16/11 2. Amino Acid Inhibitor Herbicides Other Branch ­Chain Amino Acid Inhibitor Herbicides •  Sulfonanilides –  Flumetsulam – Python –  Cloransulam – FirstRate –  Flucarbazone – Volcano 6 3/16/11 3. Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides (Growing ­Point Disintegrators) •  Like many of the other classes of herbicides, weed resistance has been reported in this group of herbicides. •  Mixing these herbicides with postemergence broadleaf herbicides frequently results in reduced grass control (antagonism). 3. Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides* •  There are two groups of chemistries in this class of herbicides known as: –  Fops –  Dims * Acetyl ­CoA Carboxylase Enzyme Inhibitors (ACCase) There is a different form of this enzyme in non ­grass plants that is not sensi1ve to this reac1on. 7 3/16/11 Fops 3. Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides •  Fluazifop –P* – Fusilade use: Agriculture crops, vegetables, tree fruits, woody ornamentals, roadsides, parks, and residen1al areas •  Diclofop – Hoelon use: wheat, barley, turf •  Quinalofop  ­P – Assure use: agronomic crops, mint, eatable beans, and establishment of wildflowers *The P in the common name indicates that the formula1on has the para or ac1ve isomer in the product. Some products have both the ac1ve and the inac1ve isomers in them. 3. Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides Dims •  Sethoxydim – Poast, Vantage use: many broadleaf crops (can be used in some turf areas such as cen1pede grass and some veri1es of fescue) •  Clethodim – Select, Envoy, Prism use: many crops but less extensive than sethoxydim 3. Grass ­Specific Lipid Biosynthesis Inhibitor Herbicides •  The fops and dims have a short half ­life in soils (5 to 15 days) and degrade rapidly. The fops can cause temporary suppression or control of germina1ng grass seeds, but for the most part there is li^le soil ac1vity. 8 3/16/11 4. Carotenoid Pigment Inhibitor Herbicides (Bleachers) •  The herbicides in this group are used on a wide range of cropping sites: agronomic crops, industrial sites, tree fruits, grapes, vegetables, and non ­croplands. The are long residual compounds that last a growing season and many can carry over into next year’s crop. 4. Carotenoid Pigment Inhibitor Herbicides (Bleachers) •  Norflurazon – Zorial, Predict, Solicam use: preemergence in alfalfa, co^on, soybeans, peanuts •  Amitrole – Amitrol ­T use: postemergence for non ­selec1ve control of woody perennials, par1cularly poison ivy and poison oak •  Clomazone – Command 3ME use: preemergence in soybeans, cucurbits, mint, pepper, rice, beans and peas, sweet potatoes (highly vola1le, must use the microencapsulated formula1on – ME) 9 3/16/11 4. Carotenoid Pigment Inhibitor Herbicides (Bleachers) •  Fluridone – Sonar, Avast use: submersed weeds in aqua1c sites •  Isoxaflutole – Balance use: preemergence in corn •  Mesotrione – Callisto, Tenacity, others use: postemergence or preemergence in corn, postemergence in turf for broadleaf weeds 10 3/16/11 5. Photosynthe)c Inhibitor Herbicides •  There are two mode ­of ­ac1on groups included is this class of herbicides: –  the “classical” photosynthe1c inhibitors –  the “rapidly ac1ng” photosynthe1c inhibitors. 5. Photosynthe)c Inhibitor Herbicides •  Clorosis first appears between leaf veins and along the outer margins of leaves. This is followed by leaf necrosis. The older leaves die first and then injury and death progresses upward with the least injury at the growing points and younger leaves. Roots are not injured by photosynthe1c inhibitor herbicides, but shoot destruc1on can lead to eventual starva1on and death of underground structures. •  Several species of weedy plants have been reported to show resistance to several of the photosynthe1c inhibitor herbicides. 5. Photosynthe)c Inhibitor Herbicides Classical Photosynthe)c Inhibitors •  Triazines •  Uracils •  Ureas 11 3/16/11 5. Photosynthe)c Inhibitor Herbicides Triazines •  Persistence depends on soil moisture, soil type, and pH. Dry soils and high pH tend to prolong persistence while high organic ma^er tends to absorb these herbicides. •  Degrada1on of this group of herbicides is primary by water hydrolysis and microbial breakdown. Triazines 5. Photosynthe)c Inhibitor Herbicides •  Atrazine – Aatrex, generic atrazine –  use: corn (preemergence and early postemergence), sorghum, warm ­season turf grass, conifers, roadsides. –  Vegetables, seeded legumes and oats are especially sensi1ve to atrazine. •  Simazine – Princep –  use: corn, fruits and nut trees, Christmas trees •  Metribuzin – Sencor, Lexone –  use: soybeans, potatoes, tomatoes, established asparagus, alfalfa. This product can be applied early postemergence to some crops. 5. Photosynthe)c Inhibitor Herbicides Uracils •  These herbicides are mostly used on perennial crops such as citrus fruits, other tree crops, and mint. Selec1vity is based on crops having deep root systems (placement within 1me and space). •  Terbacil – Sinbar –  use; established mint, alfalfa, and tree crops 12 3/16/11 5. Photosynthe)c Inhibitor Herbicides Ureas (phenylureas) •  Urea herbicides are broken down primarily by microbial ac1on and rate response is associated with soil type and organic ma^er. Ureas (phenylureas) •  Linuron – Lorox, Linuron 5. Photosynthe)c Inhibitor Herbicides –  use: mostly premergence in carrots, celery, corn, potatoes and soybeans. Used early postemergence in carrots, celery and asparagus •  Tebuthiuron – Spike, Graslan –  use: general vegeta1on control, brush control in pastures and rangeland 5. Photosynthe)c Inhibitor Herbicides Rapidly Ac)ng Photosynthe)c Inhibitors •  Bentazon •  Bromoxynil •  Primarily Foliar Herbicides that Act Like Cell Disruptor Herbicides 13 3/16/11 5. Photosynthe)c Inhibitor Herbicides •  Bentazon – Basagran –  use: soybeans, corn, eatable beans and peas. Established mint, some nursery crops, and the control of nutsedge in established turf grass •  Bromoxynil – Buctril, Moxy, Broclean –  use: corn, small grains, onions, mint, seedling alfalfa 14 3/16/11 6. Cell Membrane Disruptor Herbicides Contact Herbicides •  All are applied to the foliage (post) and cause rapid disrup1on of cell membranes and rapid kill of plant 1ssue. •  All are subject to short distant driT damage to non ­ target plants •  Paraquat – Gramoxone Max, Cyclone Max –  use: preplant or premergence (prior to crop emergence) to control weeds in a verity of crops including agronomic and vegetable row crops, as a burndown in no ­1llage, for cover crops, and established sods. For dormant treatment in alfalfa and mint. Harvest aid in soybeans, sunflower and other crops. 6. Cell Membrane Disruptor Herbicides •  Diquat – Diquat, Reward –  use: limited crop use, primary as a harvest aid in potatoes, alfalfa for seed, and turf renova1on. Main use is for aqua1c weed control. 6. Cell Membrane Disruptor Herbicides •  Dyphenylethers ­These herbicides are used in a wide variety of crops including soybeans, mint, some vegetables, and tree crops. –  Aciflurofen – Blazer –  Fomesafen – FlexStar, Reflex –  Lactofen – Cobra, Phoenix 15 3/16/11 6. Cell Membrane Disruptor Herbicides –  Carfentrazone – Aim, Affinity, Quicksilver use: postemergence in corn, forage grasses, cole crops, tomatoes, pepper, cucurbits, fruit and nut trees, turf –  Sulfentrazone – Authority, Dismiss, Spartan Use: Preplant or preemergence in soybeans and peas 6. Cell Membrane Disruptor Herbicides Glutamine Synthesis Inhibitor Herbicide •  There is only one herbicide in this group: Glufosinate. •  A non ­selec1ve post herbicide •  MOA – not certain decreases several amino acids and inhibits photosynthesis, which leads to cell membrane disrup1on and cell death. 6. Cell Membrane Disruptor Herbicides Glutamine Synthesis Inhibitor Herbicide •  Glufosinate – Ignite, Rely, Finale –  Use: directed spray in apples, berries, grapes and tree nuts as Rely –  Use: postemergence in agronomic crops with the Liberty ­Link technology as Ignite, and in turf 16 3/16/11 Gramoxone (paraquat) 7. Cell Growth Inhibitor Herbicides •  There are two basic groups within this class of herbicides: –  Microtubule assembly inhibitor herbicides ­ Root inhibitor herbicides –  Cell division inhibitor herbicides  ­ Shoot inhibitor herbicides 17 3/16/11 7. Cell Growth Inhibitor Herbicides Root Inhibitor Herbicides •  There are three chemical families of herbicides that inhibit root development by interfering with cell division: –  Dinitroanilines – most widely used –  Pyridines –  Amides 7. Cell Growth Inhibitor Herbicides Root Inhibitor Herbicides •  Dinitroaniline Herbicides (DNA’s) –  Several of the products must be incorporated into the soil due to their vola1le proper1es and their suscep1bility to photodegrada1on. –  Their MOA – interferes with mitosis 7. Cell Growth Inhibitor Herbicides Root Inhibitor Herbicides •  Dinitroaniline Herbicides (DNA’s) –  Trifluralin – Treflan, Triflualin •  must be soil incorporated –  Pendimethalin – Prowl, Pendulum, Pentagon •  applied as incorporated or surface, used in many crops including vegetables and turf –  Prodiamine – Barricade, Endurance, Factor •  Used preemergence on turf and ornamentals 18 3/16/11 7. Cell Growth Inhibitor Herbicides Shoot Inhibitor Herbicides •  The shoot inhibitor herbicides consist of two chemistry groups: –  Acetamides (chloroacetamides) –  Thiocarbamates •  MOA – not known, may inhibit fa^y acids that stop the func1on of the plasma membrane. 7. Cell Growth Inhibitor Herbicides Shoot Inhibitor Herbicides •  Acetamides (Chloroacetamide Herbicides) –  Alachlor – Intrro, Lasso, Micro ­Tech, Partner •  Used mainly in broadleaf agronomic crops and corn, can be used with grain sorghum with safener ­ treated seeds •  Similar Herbicides –  Acetochlor – Harness, Degree, TopNotch –  Metolachlor – Dual –  Dimethenamid – Fron1er 19 3/16/11 7. Cell Growth Inhibitor Herbicides Shoot Inhibitor Herbicides •  Thiocarbamate Herbicides –  EPTC – Eptam, Eradicane –  Butylate plus safener – Sutan+ Used in corn to suppress nutsedge 20 ...
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This note was uploaded on 04/03/2011 for the course BTNY 304 taught by Professor Staff during the Spring '08 term at Purdue.

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