Thakur

Pesticide By Thakur.Shashank.B

Introduction 

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The increasing pressure for food to production meet current demand requires protection of crops from pests. The use of pesticides is inevitable & constitutes an integral part of modern crop management practices. Pesticides include chemical to protect crops from insects(insecticides),weeds((herbicides),disease causing micro-organism (fungicide &bactericides), mites(acaricides), nematodes(nematicides),and rodents(rodenticides).

pesticides also include chemical that control pets directly hazardous to animals and humans,particularly vectors,suchas,mosquitoes,fleas,ticks and lice that transmit diseases.  “Natural” or “Organic” pesticide controls a pest. Organic pesticides are usually those pesticides that come from natural sources.  These natural sources are usually plants, as is the case with pyrethrum (pyrethins), rotenone or ryania (botanical insecticides), or minerals, such as boric acid, cryolite, ordiatomaceous earth. Organic pesticides are largely insecticides. 

History 

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Since before 500 BC, humans have used pesticides to prevent damage to their crops. The first known pesticide was sulfur. By the 15th century, toxic chemicals such as arsenic, mercury and lead were being applied to crops to kill pests. In the 17th century, nicotine sulfate was extracted from tobacco leaves for use as an insecticide. The 19th century saw the introduction of two more natural pesticides, pyrethrum which is derived from chrysanthemums, and rotenone which is derived from the roots of tropical vegetables. In 1939, Paul Müller discovered that DDT was a very effective insecticide. It quickly became the most widelyused pesticide in the world.

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However, in the 1960s, it was discovered that DDT was preventing many fish-eating birds from reproducing which was a huge threat to biodiversity. Rachel Carson wrote the best-selling book "Silent Spring" about biological magnification. DDT is now banned in at least 86 countries, but it is still used in some developing nations to prevent malaria and other tropical diseases by killing mosquitoes and other disease-carrying insects . -Pesticide use has increased 50-fold since 1950, and 2.5 million tons of industrial pesticides are now used each year

Characteristic of pesticides      

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They have a narrow target range They have a specific mode of action They are slow acting and have relatively critical application times They can suppress, rather then eliminate a pest population They have a limited field persistence and a short shelf life They are safer to human and the environmental than conventional pesticides They have a short residual effect.

Types of pesticide Bactericides for the control of bacteria  Herbicides for the control of weeds  Fungicides for the control of fungi  Insecticides for the control of insects these can be Ovicides, Larvicides or Adulticides  Miticides for the control of mites  Nematicides for the control of worms  Rodenticides for the control of rodents 

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Virucides for the control of viruses

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A bactericides or bactericide is a substance that kills bacteria and, Preferably, nothing else. Bactericides are either disinfectants, antiseptics Or antibiotics Phenolic substances (such as phenol (also called "carbolic acid"), Cresols (called "Lysole" in combination with liquid potassium soaps), Halogenated (chlorinated, brominated) phenols . Strong oxidizers, such as ozone and permanganate solutions;

Bacteriocide

Bacteriocidal antiseptics: An antiseptics (i.e germicide agents that can be used on human or animal body, skin, mucoses, wounds), few of the above mentioned disinfectants can be used, under proper conditions (mainly concentration, pH, temperature and toxicity toward man/animal). Among them, important are some * Diluted chlorine prepn * Iodine prepn * Phenolic compounds • Cation-active compounds Bacteriocidal antibiotics: 1. Bacteriocidal antibiotics e.g, Penicillin 2. Bacteriostatic antibiotics e.g,Aminoglycosidic

Herbicide A herbicide is a pesticide used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often based on plant hormones.  Classification of herbicides By activity, use, chemical family, mode of action, or type of vegetation controlled. By activity: Contact herbicides Systemic herbicides Soil-applied herbicides Pre-emergent herbicides Post-emergent herbicides 

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Mode of action: ACCase inhibitors ALS inhibitors EPSPS inhibitors Synthetic auxin Photosystem II inhibitors Organic Herbicides:. Organic herbicides are expensive and may not be affordable for commercial production. They are much less effective than synthetic herbicides but of course do not inject unnatural chemicals into the environment. Spice Vinegar Steam Flame

Major herbicides in use today • 2,4-D, a broadleaf herbicide in the phenoxy group used in turf and in notill field crop production • Atrazine, a triazine herbicide used in corn and sorghum for control of broadleaf weeds and grasses • Dicamba, a persistent broadleaf herbicide active in the soil, used on turf and field corn. 

2,4-Dichlorophenoxyacetic acid

General Systematic name 2-(2,4-dichlorophenoxy)acetic acid

Other names

2,4-D hedonal trinoxol

C8H6Cl2O3 Molecular formula Appearance

white to yellow powder Properties

Solubility in water

900 mg/L (25 °C)

Melting point 140.5 °C (413.5 K)

Fungicide . Fungicides are chemical compounds used to prevent the spread of fungi in gardens and crops, which can cause serious damage to the plants. Fungicides are also used to fight fungal infections.  Fungicides can either be contact or systemic  A contact fungicide kills fungi when sprayed on its surface.  . A systemic fungicide has to be absorbed by the fungus before the fungus dies. 

2-Phenylphenol

Chemical name 2-phenylphenol

Other names

o-phenylphenol biphenylol 2-hydroxybiphenyl orthophenyl phenol o-xenol orthoxenol

C12H10O Chemical formula Molecular mass 170.21 g/mol Density

1.293 g/cm³

Melting point55.5-57.5 °C Boiling point 280-284 °C

Insecticide An insecticide is a pesticide used against insects in all developmental forms. They include ovicides and larvicides used against the eggs and larvae of insects. Insecticides are used in agriculture, medicine, industry and the household  Systemic insecticides  Contact insecticides  Natural insecticides  Inorganic insecticides.  Organic insecticides 

DDT

Chemical name

4,4'-(2,2,2-trichloroethane1,1-diyl)bis(chlorobenzene)

Chemical formula

C14H9Cl5

Molecular mass

354.49 g/mol

Melting point

108.5 °C

Boiling point

260 °C

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Properties

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DDT is a colourless crystalline substance which is practically insoluble in water but highly soluble in fats and most organic solvents. DDT is created by the reaction of trichloroethanol with chlorobenzene (C6H5Cl). DDT has potent insecticidal properties

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Miticide  

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Miticides are pesticides that kill mites. Antibiotic miticides, carbamate miticides, formamidine miticides, mite growth regulators, organochlorine, permethrin and organophosphate miticides are all in this category Acaricides: Methoprene is virtually harmless to non-insects . It is widely available in supermarkets, ctc. Hydroprene is toxic to fish & perhaps birds. Both are for indoor use only, as they break down in sunlight. Methoprene is applied as a wetting spray, hydroprene as an aerosol space spray. Neither will affect adult insects; they work on future generations by preventing growth or maturation.

Carbamate:  Carbamates or urethanes are a group of organic compounds sharing a common functional group with the general structure -NH(CO)O-. Carbamates are esters of carbamic acid, NH2COOH, an unstable compound. Since carbamic acid contains a nitrogen attached to a carboxyl group it is also an amide  Carbamates in Biochemistry 

Nematicide A

nematicide is a type of chemical pesticide used to kill parasitic nematodes (a phylum of worm A nematicide is obtained from a Neem tree's Seed Cake; that is the residue of neem seeds after oil extraction. Neem tree is known by several names in the world but was first cultivated in India since the ancient times

Rodenticide Rodenticides are a category of pest control chemicals intended to kill rodents.  Single feed baits are chemicals sufficiently dangerous that the first dose is sufficient to kill.  Rodents are difficult to kill with poisons because their feeding habits reflect their place as scavengers 

Phosphine

General Systematic name

Phosphane

Molecular formula

Phosphine Phosphamine Phosphorus hydride Phosphorated hydrogen PH3

Molar mass

34.00 g/mol

Appearance

colorless gas

Other names

Properties Density and phase

1.379 g/l, gas (25 °C)

Solubility in water

31.2 mg/100 ml (17 °C)

Solubility in organic solvents

Soluble

Melting point& Boiling point

−134 °C & -87.8 oC

Bio-pesticides Biopesticides are pest management tools that are based on beneficial microorganism (bacteria, viruses, fungi and protozoa), beneficial nematodes or other safe, biologically based active ingredients.  Biopesticides include naturally occurring substances that control pest (biochemical pesticides), micro-organism that control pest (microbial pesticides),and pesticidal substances produced by plants containing added genetic PIP (Plant Incorporated Protectants) materials. 

Advantages of biopesticides  

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1. Biopesticides are inherently less harmful in comparison to Conventional pesticides 2. Biopesticides are designed to affect only one specific pest or, in some cases, a few organisms, in contrast to conventional pesticides, that may affect organisms as different as birds, insects, and mammals, across a broad spectrum. 3. Biopesticides are effective in very small quantities and often decompose quickly, thereby resulting in lower exposures and largely avoiding the pollution problems caused by conventional pesticides. 4. When used as a component of integrated pest management (IPM) programmers, biopesticides can greatly decrease the use of conventional pesticides, while crop yields remain high well.

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