Báo cáo Nghiên cứu khoa học Pesticides

PESTICIDES Tran Van Hai, Ph.D., Associate Professor Plant Protection Department, College of Agriculture & Biotechnology, Can Tho University A. INSECTICIDES 3.1. ORGANO-CHLOR GROUP Chemical pesticides have been available after World War II. - DDT is the first product. - Other organo-chlor insecticides have been subsequently produced. They are composed of C, H, O, S… and Cl. Advantages - Simply produced - Cheap - Diverse formulations (soluble powder, emulsifiable concentrate, dust, granular, etc.) - Easily applied in field conditions - Broad-spectrum, high and long-term effect - Stable and therefore easily stored - Easily degraded in basic condition Disadvantages - Long-term persistence in soil and plants - Polluting environment - In natural conditions, DDT totally degraded within ten years. - Persisting in food chains and residing mainly in adipose tissues of animal and human bodies - Having chronic toxicity and therefore causing cancers, monstrosity, etc. - Having high toxicity on fish and natural enemies SOME ORGANO-CHLOR INSECTICIDES COMMONLY USED IN THE PAST 1. DDT (Dichloro-diphenyl-trichloetan) - Commercial products : DDT, GESAROL, ZEDAN - Common formulations: 30EC, 75WP, 10D, 5G, etc. - Technical name: 1,1,1- Trichloro- 2,2 bis (p- chlorophenyl) ethane - Toxicity: LD50 (on mice) = 113mg/kg (the first toxic class) - Being banned 2. BHC - Commercial names: LINDAFOR 90, lindane, 6-6-6, HCH, etc. - Common name: Benzen hexa chlorit - Structural formula: C6H6Cl6 - Toxicity: LD50 = 125mg/kg (the first toxic class) - Being banned 3.ENDOSULFAN - Commercial products: Thiodan 35EC, Thiodol 35EC, Tigiodan 35EC, Endosol 35EC, Thasodan 35 EC - Products are dark red in color and easily degraded in basic condition. - Having light toxicity on honey bees and some natural enemies - Having high toxicity on fish - LD50 (on mice): 40-100mg/kg - Commonly applied on corn, bean, cotton, tobacco, and coffee - Dosage: 350-500g ai/ha (1-1,5 l/ha) -Thiodan belongs to the first toxic class. It is reduced from use in Vietnam. ACTION MECHANISM OF INSECTICIDES Cruiser Plus tác động trực tiếp đến hệ thần kinh của bọ trĩ, đặc biệt là the post synaptic nerve. Sodium Channel: Pyrethroids Acetylcholine esterase: OP’s, Carbamates Acetylcholine receptor: Neonicotinoids Pre-synapse Post-synapse Synaptic Cleft Actara acts on signal receptor of the central nervous system. 3.2. ORGANO-PHOSPHATE GROUP - Composed of C, H, O, S… and P. - Broad spectrum (effective on Coleoptera, Lepidoptera, Homoptera, Orthoptera, Diptera,Hemynoptera and Hemiptera, etc.) - Mode of action: contact, oral and fumigation - Persisting shortly in environment - Rapid effect - Having high acute toxicity due to fast accumulation and strong effect on the nervous system - Excreted via urination - Atropine is one of the detoxicators. - Having high toxicity on warm-blooded animals and natural enemies - Easily degraded in either acidic or basic condition - Easily soluble in organic solvents but low in water 1. METHYL PARATHION - Commercial names: Metaphos, Wofatox, Folidon M, Metacid - Common formulations: 50EC; 1.5D - Toxicity: LD50 (on mice) = 25-50mg/kg (the first toxic class) - Methyl parathion is oxidized inside insects to form Paraoxon which has higher toxicity. - Being banned 2. METHIDATHION ( Supracide 40EC, Suprathion 40EC) 3.DIAZINON (Basudin 40EC, 50EC, 10H) 4. NALED (Dibrom 50EC, 96EC) 5. ENTHOPROPHOS, ETHOPROP (Mocap 10G, NoKaph 10G, 20EC, Vimoca 20EC) 6. DIMETHOATE (Bini 40EC, Bian 40EC, Bi58 40EC, Dithoate 40EC, Tigithion 40EC) 7.ACEPHATE (Monster 40EC, 75WP; Mytox 75SP; Orthene 97 Pellet) 8.DICHLOROVOS, DDVP (Demon 50EC): reduced from use 9.MONOCROTOPHOS (Azodrin 40DD, Nuvacron 40SC, Magic 50SL, Apadrin 50SL) the first toxic class, being banned 10.METHAMIDOPHOS (Monitor 50EC, Filitox 70SC) the first toxic class, being banned 3.3 CARBAMATE GROUP - Structural formula: derivative of carbamic acid (NH2- COOH) - Narrow-spectrum, specific on sucking & chewing insects - Mode of action: contact, oral and some of fumigation - Persisting shortly in environment - Rapid effect - Having high acute toxicity due to fast accumulation and strong effect on the nervous system - Excreted via urination - Atropine is one of the detoxicators. - Having lighter toxicity on warm-blooded animals, natural enemies and fish as compared to the organo- phosphate insecticides. - Easily degraded in either acidic or basic condition - Easily soluble in organic solvents but low in water 1. CARBARYL - Commercial products: Sevin 50 WP, 15 EC - Stable under UV and high temperature - Easily degraded in basic condition - Toxicity: LD50 (on mice) = 560mg/kg - Non-persistence in animals - Usage: Sevin acts via surface contact or oral entry. It is used with the concentration of 1- 3%o to control fruit-tree insects (Leaf folder, Mealy bug, Scale, etc.), industrial-crop insects (cotton, tobacco army worms.) 2. ISOPROCARB (MICP) Mipcin 20 EC, Mipcide 20 EC, Vimipc 20EC, Tigicarb 20EC, 20 WP 3.PHENOBUCARB (BPMC) Bassa 50EC, Bassan 50EC, Bassatigi 50 EC, Vibasa 50EC, Hopkill 50EC, 4.CARBOFURAN Furadan 3G, Vifuran 3G, Kosfuran 3G The first toxic class, reduced from use 5.METHOMYL Lannate 40SP, Cofitex 24 SL The first toxic class, reduced from use 3.4. SYNTHETIC PYRETHROIT GROUP - Pyrethrin was extracted from Pyrethrum cinerariaetrifolium in the 1960s. - Broad spectrum: specific on chewing & sucking insects, especially on larva of Lepidoptera - Mode of action: contact and oral, weak effect by fumigation and non systemic - Persisting shortly in environment and easily degraded under sunlight and high temperature - Applied with much lower dosages as compared to that of organo-chlor, organo-phosphate, and carbamate insecticides - Having weak acute toxicity - Acting on the nervous system and causing oxygen deficiency - Excreted via urination - Having light toxicity on warm-blooded animals - Causing pest resistance rapidly in case of uncontrolled use - Easily soluble in organic solvents but low in water 1. CYPERMETHRIN -Commercial products: Sherpa 10EC, 25EC, Shertox 5EC, 10EC, 25EC, Sherbush 5EC, 10EC, 25EC, Shertox 5EC, 10EC, 25EC, , Southsher 5EC, 10EC, 25EC, Visher 25DC, Cyperan 5EC, 10EC, 25EC, Cyperkill 5EC, 10EC, 25EC Cypermap 10EC, 25EC Cypersect 5EC, 10EC, Arrivo 5EC, 10EC - Easily degraded in basic condition - The second toxic class, LD50 per os: 215mg/kg - Mode of action: contact and oral - Used to control sucking insects, especially on Lepidoptera such as chewing insects - Dosage: 25-200g a.i/ha (depending on kind of crops) 2. ALPHA CYPERMETHRIN Fastac 5EC, Alpha 5 EC, Alphan 5 EC, Vifast 5 EC, Cyper Alpha 4 ND 3. DELTAMETHRIN Decis 2,5EC, Delta 2,5EC, Deltox 2,5EC, Appendelta 2,8 EC 4. CYHALOTHRIN Karate 2,5EC, Vovinam 2,5EC, Sumo 2,5EC, FastKill 2,5EC. 5. FENPROPATHRIN Danitol 10 EC, Vimite 10ND 6. FENVALERAT Sumicidin 10EC, 20EC; Pyvalerate 20EC, Sanvalerate 20EC, Vifenva 20ND, 7. PERMETHRIN Peran 10EC, 50EC, Perkill 50EC, PER Annong 100EC, 500EC, Ambush 50EC,Tigifast 10EC 3.5 BIO-INSECTICIDES 1. HORMONES - Hormones are substances produced from endocrines of living organisms to control their physiological activities. Hormone juvenin: -Etofenprox (Trebon 10EC, 20EC, 30EC) -Buprofezin (Applaud 25WP, 40SC, 2G) -Telubenzuron (Nomolt 5SC) -Chlorfluazuron (Atabron 5EC) -Lufenuron (Match 50 EC) -Tebufenozide (Mimic 20F) 2. PHEROMONES - Pheromones are substances produced by insects to form their inter-species relationship. -Methyl eugenol which could attract fruit fly Dacus dorsalis in fruit orchards - Methyl eugenol 75% + Naled 25%: Ruvacon 90 L and Vizubon D for 2-3 traps/1.000m2 - Methyl eugenol applied to remove male of fruit fly in order to reduce density of current populations - Advantages: highly selective ability, harmless to environment, and preventing insect resistance 3. MICROBIAL INSECTICIDES + Fungal insecticides: -Abamectin (Vertimec 1,8EC, Vibamec 1,8EC, Abatimec 1,8EC, Nockout 1,8EC, Tap ky 1,8EC): Streptomyces avermitilis -Spinosad (Success 25SC): Actinomycetes -Beauveria bassiana: (Beauverin, Boverit 5x108 CFU ) -Metarhizium ansopliae: (Mat 5.5x108 spores/g) Coconut beetles and larvae of armyworm infected by Metarhizium anisopliae + Bacterial insecticides: -Bt. is one of the bacterial insecticides produced from Bacillus thuringiensis. - Applied to control: Plutella xylostella, Trichoplusia ni, Pieris brassicae, etc. It is also capable of controlling insects which are less susceptible to Bt. such as Spodoptera litura and Heliothis armigera * Common bio-insecticides derived from Bacillus thuringiensis: -Bacillus thuringiensis var. kurstaki ( Biocin 16 WP, Dipel 6.4 WP, Forwabit 16 WP, Thuricide HP, MVP 10FS) -Bacillus thuringiensis var. aizawai (Aztron 7000 DBMU, Bathurin 3-5xIO9, Xentari 35 WDG) Action mechanism of Bt. Bacillus thuringiensis Cry Parasporal body δ -endotoxin Spore Mode of action of Bacillus thuringiensis Ingestion Producing activated toxin Columnar cell Cells are swollen Specific binding site toxin Crystal toxin of Bt. + Viral insecticides: - NPV (Nucleotid Polyhedrosis Virus): Insects become glassy and stop eating. Their bodies swell. Their skins turn necrosis and color greyish black. When being killed, larvae bodies attach to plant tissues and hang on the plants. - GV (Granulosis Virus): Insects become glassy and stop eating. Their body segments become stunt, discolor and turn to white or yellowish white. Oclusion bodies of NPV observed under electron and fluorescent microscopes A larvae infected by NPV Larvae infected by GV B. FUNGICIDES 3.1. CLASSIFICATION BASED ON MODES OF ACTION 3.1.1 Protective fungicides: This kind of fungicides is to prevent diseases. They are normally sprayed when plants are not diseased or slightly infected. 3.1.2 Preventive fungicides: This kind of fungicides is to kill fungi in infected areas right after the pathogens penetrate plant cells. Ex: Mercury and sulfur fungicides, lime, etc. 3.1.3 Therapeutant: This kind of fungicides is capable of + lessening disease symptoms by inactivating toxins produced from pathogens + inducing plant resistance (SAR= Systemic Acquired Resistance) 3.2 CLASSIFICATION BASED ON CHEMICAL STRUCTURES 3.2.1 Copper fungicides - Usage: spraying, seed treating, soil treating - Inhibiting fungi by surface contacting and persisting in the environment - Cu++ acts on spores or mycelia of fungi, precipitates or denatures their proteins, and deactivates their enzymes. Advantages: being cheap, having wide-range effect, and being relatively safe for warm-blooded animals and human Disadvantages: could harm plants in case of high concentration of free Cu++, especially in frosty condition. a. Bordeaux mixture - Formulation: 4CuSO4 + 3Ca(OH)2  CuSO4.3Cu(OH)2 + 3CaSO4 - Amount of Ca(OH)2 is normally added to neutralize pH. - Bordeaux 1% is made by ratio CuSO4 : Ca(OH)2 : H2O =1:1:100. - At concentration of 3-6%, the mixture can control moss, algae and lichen. - Usage: the mixture is competent in controlling fungi and bacteria + Spraying: control many fungal pathogens causing leaf spot, blast, downy mildew, rust, brown spot… + Bordeaux 5% can be applied directly on lesions to control trunk canker Phytophthora palmivora on rubber, citrus, and durian. + Nursery treating: control Pseudomonas sp. causing seedling damping-off COPPER-ZINC (ZINC-COPPER) + Zinc-copper: 35% Oxychlorua Cu+ 15% Zineb +50% adjuvant + Copper - zinc: 60% Dry Bordeaux + 25% zineb + 15% adjuvant Seed treatment: mix 2-4g mixture/kg seed in 4-5 hrs before seed soaking or sowing Soil treatment: applied 1 - 3 l/m2 (0,1%) to prevent root diseases COPPER - B - 45% Dry Bordeaux + 20% Zineb + 10% Benomyl + 25% adjuvant + Rice sheath blight: spray 0,2- 0,3% mixture for 2 times in 10-15 days + Other diseases: grain discoloration; yellow leaf, brown spot of rice + On citrus: brown spot, canker, root rot. b. OXYCHLOR COPPER - Common products: COC 85 WP, Cuivre Oxyclorua 80 WP, 50 HP - Formula: 3Cu(OH)2 .CuCl2 or 3CuO.CuCl2. 4H2O - Usage: to control many fungal & bacterial pathogens such as brown spot, rust, anthracnose, downy mildew, black mildew, algae spot and canker - Dosage: 5-7 liters Copper Oxychlorua 30HP/ha. Note: Do not applied together with basic pesticides. c. HYDROXID COPPER - Commercial products: Champion 77 WP, Kocide 61 DF, Funguran 50 WP - Formula: Cu(OH)2 - Usage: leaf and stem canker, algae spot, lichen on citrus… - Apply 0,2-0,3% by spraying on leaves or watering into root areas. Note: Do not applied together with basic pesticides. 3.2.2 SULFUR FUNGICIDES 3.2.2.1 Inorganic sulfur (S) - Common names: Kumulus, Microthiol - Application rate: 2-5 kg of commercial product 80WP/ha - Fungi disease of Oidium sp.: applied in early stage of infection - Mode of action: S is oxidized to SO2 or reduced to H2S therefore inhibits respiration. - Belonging to the third toxic class, relatively harmless to animal and human MRL: 25-50mg/kg; PHI: 3 days, medical herbs: 14 days. - Also applied to control red, broad, and rust mites on citrus 3.2.2.2 Organic sulfur: (Dithiocacbamat metal compounds) derivatives of dithiocarbamic acid a. Zineb - Common products: Dithane 72 WP, Tigineb 80 WP, Zin 80 WP - Technical name: Zinc-etylenbis (dithiocacbamat ) b. Mancozeb - Common products: Dithane M-45 80WP, Penncozeb 80 WP, Man 80 WP, etc. - Technical name: Mangan-etylenbis (dithiocacbamat), zinc complex c. Propineb - Other names: Mezineb, Antracol - Technical names: Polymeric-zinc-propylenebis (dithiocacbamat) 3.2.3 Mercury fungicides - High toxicity on warm-blooded animals and human, persisting in their bodies - Inorganic compounds: HgCl, HgCl2 - Mercury compound: the first toxic class, reduced from use 3.2.4 DICACBOXIN FUNGICIDES - Contact, low in systemic, safe for use - Capable of controlling sclerotia-forming fungi such as Rhizoctonia sp., Sclerostinia sp. - Active ingredient: Iprodione - Commercial product: Rovral 50 WP. - Iprodione 0,1-0,2% is applied to control Sclerotium, Alternaria, Fusarium, Helminthosporium, Rhizoctonia on vegetables and fruit-trees. - Apply 1,5-1,7 kg/ha of commercial products to control rice sheath blight and grain discoloration 3.2.5 SYSTEMIC ORGANO-FUNGICIDES 3.2.5.1. Organo-phosphate fungicides - Systemic and Preventive effect - Relatively narrow spectrum effect - Relatively harmless to warm-blooded animals and human - Capable of controlling some insects + Active ingredient: Iprobenfos (IBP) - Commercial products: Kitazin, Kian, - Common formulation: 50ND, 5H,10H - Usage: applied to control leaf blast, panicle neck rot, and foot rot diseases on rice + Active ingredient: Edifenfos - Commercial products: Hinosan 30ND, 40ND; Canosan 20EC,40DC,50EC, Agrosan 40EC, 50EC - Usage: Applied to control leaf blast, sheath blight, and sheath rot diseases on rice 3.2.5.2. Carbamate Fungicides - Having broad spectrum effect, especially effective on sclerotia-forming fungi, however, showing weak effect on Phycomycetes: Alternaria sp., Helminthosporium sp. - Relatively harmless to animals and human + Active ingredient: Benomyl - Common names: Fundazol, Fundozol - Commercial products: Bemyl 50 WP, Ben 50 WP, Bendazol 50 WP, Viben 50 WP, Benlate 50 WP, etc. - Usage: having systemic and wide-range effect, being capable of controlling fungal diseases on vegetables, industrial crops, fruit-trees, and bonsais - 1-2 kg/ha of Benomyl 50 WP is applied to control sheath blight, grain discoloration of rice; anthracnose and soft rot of fruits. + Active ingredient: Carbendazim - Commercial products: Carbenzim 50 WP, Carban 50 SC, Bavistin 50 FL, Derosal 50 SC, Carosal 50 WP, Appencarb supper 50 FL, etc. - Sharing the same characters with Benomyl - Being applied to control root fungal diseases 3.2.5.3. Triazole fungicides - Very commonly used in recent years - Strong systemic, wide-range and hight effect - Applied to control downy mildew, rust, black mold, root rot of vegetables and fruit trees; sheath blight of rice. - This fungicide inhibits Ergosterol biosynthesis as well as appressoria and haustoria formations. a. Hexaconazole - Anvil 5SC b. Diniconazole - Dana Win 12,5 WP , Sumi- Eight 12,5 WP c. Propiconazole - Tilt 250EC d. Cyproconazol -Bonanza 100L e. Triadimenol - Bayfidan 25 EC, Samet 15 WP. 3.2.6 OTHER SYNTHETIC ORGANO-FUNGICIDES a. Isoprothiolane - Fuji-one 40 ND b. Pencycuron - Monceren 25WP c. Fosetyl-aluminium - Aliette 80WP d. Cymoxanil - Curzate M8 e. Metalaxyl - Ridomil 240 WP, Vilaxyl 25 WP 3.2.7 Microbial fungicides - Products extracted from microorganisms + Antagonistic microorganisms: Trichoderma lignorum,Trichoderma harzianum Products made by the Dept. of Plant Protection, CTU: Trico-DHCT, applied to control root rot diseases on fruit-trees and vegetables + Antibiotics: * Active ingredient: Kasugamycin Extracted from Streptomyces kasugaensis, applied to control rice leaf blast and bacterial diseases. - Common products: Kasumin 2 L, Cansumin 2 L - Applied to control bacterial pathogens on citrus * Active ingredient: Validamycine - Extracted from Streptomyces hygroscorpicus - Commercial products: Validan 3 L, 5 L; Validacin 3 L, 5 L , - Applied to control rice and corn sheath blight diseases; seedling damping-off, root rot, etc. C. Herbicides3.11.1 Definition of Weeds Weeds are plants which grow unexpectively at the time and in the cultivated areas therefore adversely affect crop production. 3.11.2 Characteristics of weeds - Rapid growth: a seed of Co long vuc can (Echinochloa colona) could bear 50 seedlings after 45 days of sowing - Drought resistance: Co Tuc Hinh (Digitaria sanguinalis), Co Tranh (Imperata cylindrica), Co Cu (Cyperus rotundus) - Dormancy: when being buried deeply under soil layers, physiological processes of weed seeds are repressed, therefore they stop growing and developing. Co Long Vuc seeds (Echinochloa spp.) could continue growing within 4 months after being buried under soil layers. - Broad propagation: weed seeds are light and hairy hence could be dispersed by winds broadly. They are aeriferous therefore could float and be dispersed by water flows. Weed seeds have hook-like structure so could attach to insect hairs. Additionally, cultivation activities of farmers are also favorable for weed seed dispersion. a. Life cycle - Annual herbs: life cycle is within a year. Life cycle of this kind of weeds normally follows crop rotation. Ex: Co Long Vuc (Echinochloa spp.), Co Duoi Phung (Leptochloa chinensis) - Biennial herbs: life cycle is within two years; the first year is for vegatative growing and the second year is for reproduction. Ex: Carduus nutans (Compositae) - Perennial herbs: life cycle is more than two years. Flowering is normally in the second year and continuously in the third year. Ex: Co Man Trau (Cynodon dactylon), Co Cu (Cyperus rotundus), Rau Ma (Centella asiatica) c. Morphology CO HOA BAN: Grass (Poaceae group) - Stem is cylindrical, hollow, being internodes. - Leaf blades envelope the stem in form of sheaths. Leaves are long, narrow, hairy, erect vertically with the stem. - Veins of the leave are parallel. Two sides of the leaves got similar structure. - The leaf blades and the leaves are easily differentiated. Seeds are hermetically structured. - The inflorescence is a pannicle - Rhizomes are spreading, slender and fleshy. Ex: Co Long Vuc (Echinochloa spp.), Co Duoi Phung (Leptochloa chinensis), Co Long Tay ( Brachiaria mutica), Co Tuc Hinh (Digitaria spp.) CO CHAT LAC: Sedges (Cyperaceae group) - Stems are erect, unbranched, rigid, porous, smooth and triangular, usually distributed in 2 opposite leaves per round of axial stem. - Leaf blades and leaves are not easily differentiated. The leaves are long, narrow. Veins of the leaves are parallel. - Leaves are erect vertically with the stem, usually distributed in 3 leaves per round of axial stem. - Infloresence is simple or compound - Rhizomes are spreading, slender and fleshy. Ex: Co Chac (Fimbristylis miliaceae), Co Chao (lac Mo) (Cyperus difformis), Lac Ran (Cyperus iria), Co Cu (Cyperus rotundus), Co nang (Eleocharis dulcis). Broadleaf weeds: - Stem is normally cylindrical, round, branched. - Leaves are wide, diverse in forms, and different in structure at two sides. - Veins of the leaves are usually branched such as Co Xa Bong (Sphenoclea zeylanica), Rau Den (Amaranthus spinosus), Rau Muong (Impomea aquatica), Rau Muong (Lugwigia octovalvis). - Veins of the leaves are parallel from top of stalk such as Rau Mac Bao (Monochoria vaginalis), Rau Bo (Marsilia minuta). - Flowers well develop and possess many petals. - Inflorescences are diverse: simple, dense or compound, etc. 3.11.3 Herbicides 3.11.3.1 Definition Herbicides are agro-chemicals which are chemically or biologically synthesized, applied to either kill weeds or repress their growth and development. 3.11.3.2 Classification a. Selective herbicides This kind of herbicides acts selectively on specific weeds. Ex: 2,4-D could control only broadleaf weed and sedge; Whip’s 75 EW could do selectively Co long Vuc and Co Duoi Phung b. Non-selective herbicides This kind of herbicides acts unselectively on all weeds and plants which they could contact, including cultivated plants. Ex: Gramoxone 20SL (Paraquat), Basta 15SL (Glyphosinate amonium) Glyphosan 480DD (Glyphosate), Spark 16WSC (Glyphosate) c. Usage - Pre-cultivation herbicides: Glyphosate (Touchdown 48SL, Roundup 480SC, Glyphosan 480DD), Paraquat (Gramoxone 20SL), Metolachlor (Dual 720ND). - Pre-emergency herbicides: kill weeds before their seeds are about to germinate or while they are germinating. Fields which are flat and humid enough enhance herbicide effect. Meco 60ND (Butachlor) and Sofit 300ND (Pretilachlor) enter weeds via young root and young leaf. - Post-emergency herbicides: kill weeds after they have grown. This kind of herbicides enters weeds and plants via mostly their leaves and partially their roots. Ex: Whip’s 75 EW, Saviour 10 WP (Cyclosulfamuron), Butanil 55EC (Propanil 27,5% + Butachlor 27,5%), Michelle 62EC, Echo 60EC, Vibuta 62EC (Butachlor), Sindax 10WP (Londax 8,25% + Ally 1,75% ), and Anco 720EC (2,4-D). d. Classification based on modes of action - Contact herbicides: This kind of herbicides could kill plant tissues where they contact as well as adjacent areas. Ex: Gramoxone 20SL (Paraquat), Butanil 55EC (Propanil 27,5%+ Butachlor 27,5%). - Translocative herbicides: Active ingredient moves far from where it contacts plant tissues Most of the recently year, commercial products are translocative herbicides. Ex: Glyphosate: (Touchdown 48SL, Roundup 480SC, Glyphosan 480L), 2,4-D: (Anco 720L, Vi 2,4-D 700L). e. Classification based on natural chemical structure Inorganic herbicides: recently unpopular due to their slow degradation and high persistence in environment. - Cyanamid calcit Ca(CN)2 - Chlorat natri (NaClO3) - Copper sulfat (CuSO4 . nH2O) Organic herbicides: commonly used recently 1. Phenoxycarboxylic acid group - 2,4-D (Vi 2,4D 80WP, Anco 720L), Vi 2,4D 600L,Vi 2,4D 700L) - MCPA (Methyl Chlor Phenoxy Acetic acid). - Acting similarly with auxin, disturbing weed growth, discoloring their leaves, and causing the leaves brownish black and twist. - Penetrating through leaves, being selective, and having post-germination mode. - Effective on broadleaf weeds and sedges. 2. Carbamate group Derivatives of carbamic acid (NH2-COOH) - Thiobencarb (Saturn 6H, 50ND) - Affect on photosynthesis, inhibit cell division, and repress lipid synthesis. - Penetrate via leaves, roots, and shoots: having pre-germination mode, being selective - Effective on sedges, poaceae,, and broadleaf weeds 3. Amides group - Propanyl (Wham 360EC), Butachlor (Cantachlor 60EC, 5G; Vibuta 62EC, 5G, Michelle 62EC, Meco 60EC), Pretilachlor (Sofit 300EC), Melolachlor (Dual 720EC) - Affect remarkably on Hill reaction of photosynthesis and inhibit chlorophyll synthesis. - Most of herbicides of this group are contact, got pre or post-germination mode, could be applied before or after weed growth. - Effective on sedges, poaceae, and broadleaf weeds. 4. Ureas - Liuron (Afalon 50WP), Diuron (Karmex 80WP) - Affect on Hill reaction of photosynthesis and inhibit energy generation (ATP and ADP synthesis) - Selective and translocative - Effective on annual, sometimes on perennial weeds, ex: Bushes 5. Sulfonilureas - Bensulfuron-methyl (Londax 10WP), Metsulfuron-methyl (Ally 20DF). - Inhibit biosyntheses, stopping cell growth and division - Selective and up & down translocative via leaves and roots - Pre and post-germination modes - Effective on annual and perennial weeds 6. Triazines - Ametryne (Gesapax 500DD), Atrazine (Atra 500SC), Simazine (Visimaz 80WP). - Affect on Hill reaction of photosynthesis and inhibit electron transportation - Selective and translocative via leaves and roots - Effective on mono and dicotydon weeds 7. Bipyridylium - Paraquat (Gramoxone 20SC) (Farmers normally call Thuoc Co Chay.) - Affect on photosynthesis and destroy chloroplasts. - Contact, partially translocative via leaves - Unselective - Effective on annual, biennial, and perennial weeds 8. Organo-phosphate group - Glyfosinate ammonium (Basta 15L), Anilofos (Ricozin 30EC) - Affect on photosynthesis, inhibit NH3 transformation, and therefore be harmful to plants - Contact and semi-translocative, absorbable via leaves but rarely via roots - Non-selective, effective on poaceae and broadleaf weeds 9. Glycines - Glyphosate (Glyphosan 480L, Roundup 480SD, Vifosat 480L, Spark 16SC) - Affect on photosynthesis, inhibit amino acid and protein biosynthesis, and change chloroplast structure - Contact, high translocative and systemic, absorbable via leaves and roots - Non-selective, effective on poaceae and broadleaf weeds in orchards 10. Aryloxy-phenoxy-propionates - Phenoxaprop -P- ethyl (Whip’s 7,5EW), Fluazifop -P- butyl (Onecide 15EC), Cyhalofop - butyl (Clincher 10EC). - Inhibit biosynthesis of fatty compounds - Selective, translocative via leaves and stems - Post-emergency mode - Effective on sedges, poaceae and broadleaf weeds. Dịch hại Ngưỡng tác động Ưu tiên 1 Ưu tiên 2 Ưu tiên 3 Rệp sáp, vãy, dính 5-10% lá bị hại SK 99 Fenobucarb Methidation Rệp sáp giả, bọ xít 5-10% lá bị hại SK 99 Fenobucarb Dimethoate Rầy mềm 10-20% chồi non bị hại SK 99 Buprofezin Etofenprox Rầy phấn trắng 5-10% lá bị hại SK 99 Fenobucarb Methidation Rầy chổng cánh Bát đầu xuất hiện trứng, ấu trùng, thành trùng/đọt non SK 99 Fenobucarb MCPA Bù lạch 1-2 con/ hoa, chồi non, trái trong mùa khơ SK 99 Abamectin Thiamethoxam Sâu vẽ bùa 15-20 % lá bị hại SK 99 Bt. Lufenuron Sâu ăn lá 15-20 % lá bị hại SK 99 Chlorfluazuron Lufenuron Ruồi đục quả 1-2 thành trùng/trái SK 99 Methyl-eugenol Protein SOFRI Nhện hại Vài chục con/lá, trái, chồi trong mùa khơ SK 99 Propargite Hexythiazox Ngài đục quả Thành trùng bắt đầu xuất hiện trên trái SK 99 Cypermethrin Diazinon Table 1. Insects which could be controlled by applying mineral oils and agro-chemicals Table 2. Citrus diseases which could be controlled by applying agro-chemicals Dịch hại Ngưỡng tác động Ưu tiên 1 Ưu tiên 2 Ưu tiên 3 Thối rễ Vài lá bắt đầu vàng, rụng, rễthối Tricoderma Carbendazim Metalaxyl Ghẻ vi khuẩn Vài đốm bệnh xuất hiện trên lá mùa mưa Copper Bordeaux Kasugamycin Ghẻ do nấm 5-10% đốm bệnh xuất hiện trên lá mùamưa Copper Zineb Benomyl Xì mũ gốc 1-2% cây bắt đâu nhiễm bệnh Copper Metalaxyl Fosetyl aluminium Địa y, đốm đồng tiền, đốm rong 40-50% vết bệnh trên thân Copper Bordeaux Paraquat Đốm mỡ lá 40-50% % vết bệnh trên lá Zineb Carbendazim Benomyl Thán thư chồi, lá, bơng, trái 1-2% chồi non, hoa, trái nhiễm bệnh Mancozed Zineb Benomyl Thank you!