Basic introduction Chinese name: bactericide mbth: industrial bactericide Pinyin: sand definition: classification of chemicals for preventing and controlling various pathogenic microorganisms: bactericide, virus killer and algicide-induced events: organic mercury compounds for preventing and controlling wheat smut components: mode of action of inorganic compounds: protective bactericide, systemic fungicide background, main types, agricultural bactericide, industrial bactericide by application field, raw material source of bactericide by inorganic bactericide, Organosulfur bactericides, organophosphorus and arsenic bactericides, substituted benzene bactericides, oxazole bactericides, antibiotic bactericides, compound bactericides and other bactericides, classified according to the use mode of bactericides, protective agents and therapeutic agents, classified according to the conductivity characteristics, systemic fungicide, non-systemic fungicide, protective bactericides, development history, operation methods, important functions, industrial application fields, application in industrial circulating cooling water, application in water-based coating industry, Matters needing attention, determination method, spore germination determination method, bacteriostatic circle method, growth rate determination method, development prospect and background According to investigation, pathogenic microorganisms (fungi, strong bacteria, rickettsia and mycoplasma) are harmful to plants all over the world. Plant diseases have caused great losses to agriculture. The annual output of crops in the world is about 500 mt, and there have been many disasters in history, such as severe famine and even a large number of people starved to death due to the prevalence of a certain plant disease. Using fungicides is an economical and effective method to control plant diseases. The main types of fungicides, also known as biocides, fungicides and microbicides, usually refer to chemical agents that can effectively control or kill microorganisms-bacteria, fungi and algae in water systems. Mainly divided into agricultural fungicides and industrial fungicides. Agricultural fungicides are a kind of pesticides used to prevent and control plant diseases caused by various pathogenic microorganisms, generally referring to fungicides. However, it is usually regarded as the general name of drugs for preventing and treating various pathogenic microorganisms in the world. With the development of fungicides, they can be divided into three categories: fungicides, virus killers and algaecides. Industrial fungicides can be divided into oxidizing fungicides and non-oxidizing fungicides according to sterilization mechanism. Oxidative bactericide is usually a strong oxidant, which mainly oxidizes with metabolic enzymes in bacteria to achieve the purpose of sterilization. Commonly used oxidizing bactericides include chlorine, chlorine dioxide, bromine, ozone, hydrogen peroxide, etc. Non-oxidizing bactericides act on the special parts of microorganisms in the form of toxic agents, thus destroying the cells or living bodies of microorganisms and achieving the sterilization effect. Common non-oxidizing fungicides include chlorophenols, isothiazolinone and quaternary ammonium salts. Fungicides Fungicides are classified according to their sources. Except for agricultural antibiotics, which belong to biological fungicides, the main varieties are chemical synthetic fungicides, which are a kind of drugs used to prevent and control plant diseases. Any agent that can kill pathogenic bacteria or inhibit growth, but does not interfere with the normal growth of plants, is collectively called fungicide. Fungicides can be classified according to the mode of action, source of raw materials and chemical composition. According to the application fields, it can be divided into industrial fungicides and agricultural fungicides. Inorganic bactericide, such as sulfur powder, stone sulfur mixture, copper sulfate, mercuric chloride, lime Bordeaux solution, copper hydroxide, cuprous oxide, etc. According to the source of raw materials, fungicides are classified. Bactericide Organic sulfur bactericide, such as amobam, diclofenac sodium, thiram zinc, zineb, mancozeb, thiram, etc. Organophosphorus and arsenic fungicides, such as Daowenjing, Kewen powder, ethyl phosphate, methyl chlorophosphate, tuijunte, Daojiaoqing, etc. Substitute benzene bactericides, such as thiophanate-methyl, chlorothalonil, trichlorfon, pentachloronitrobenzene, etc. Azole fungicides, such as triadimefon, carbendazim, hymexazol, benomyl, thiabendazole, etc. Antibiotics and fungicides, such as Jinggangmycin, polyoxin, kasugamycin, agricultural streptomycin, antifungal mycin 120, etc. Compound fungicides such as mirex, shuangxiaoling, Fu Mei anthrax, antiviral alum M8, metalaxyl copper, DT fungicide, metalaxyl manganese zinc, seed dressing agent, thiophanate-methyl manganese zinc, broad sterilization milk powder, metalaxyl thiram wettable powder, etc. Other fungicides such as metalaxyl, carbendazim, procymidone, chlorpheniramine, chlordane, Teflon, dichlorvos, Ralstonia solanacearum, formalin, high-fat film, mycotoxin, propamocarb, quinconazole, dimethomorph manganese zinc, etc. According to the use of fungicides, the protective agent is to treat plants or the surrounding environment with chemicals before pathogenic microorganisms contact or soak plants, so as to inhibit the germination of pathogenic spores or kill the germinated pathogenic spores, thus protecting plants from harm. This function is called protection. Preparations with this effect are protective agents. Such as Bordeaux solution, zineb, copper sulfate, green milk copper, mancozeb, chlorothalonil, etc. Therapeutic agent The therapeutic agent pathogenic microorganism has been immersed in the plant, but the symptoms of the plant are in the incubation period. Drugs penetrate into plant tissues from plant epidermis, and kill or inhibit pathogenic bacteria through transportation, diffusion or production of metabolites, so that diseased plants are no longer harmed and their health is restored. Agents with this therapeutic effect are called therapeutic agents or chemotherapeutic agents. Such as thiophanate-methyl, carbendazim and kasugamycin. 3. Eradicator refers to the pathogen that can directly kill the invading plants after plant infection. The agent with this eradication effect is the eradicator. Such as thiram arsenic, sodium pentachlorophenol, stone sulfur mixture, etc. Systemic fungicide systemic fungicide can be absorbed by leaves, stems, roots and seeds of plants, transported, diffused, retained or produced metabolites by plant body fluids, which can prevent and treat some diseases that go deep into the endosperm of plants or seeds, thus protecting crops from infection by pathogenic bacteria or treating infected plants, so it has therapeutic and protective effects. For example, carbendazim, rickettsia, Luheng No.2, Duomuqing, first frost Epidemic Prevention, clothianidin, metalaxyl, dihydrophosphorus phosphate, thiophanate-methyl, dixone, triadimefon, metalaxyl, antiviral alum, seed dressing double, etc. Non-systemic fungicide and non-systemic fungicide means that drugs cannot be absorbed, conducted and retained by plants. Most of the varieties are non-systemic fungicide, which is not easy to make pathogenic bacteria resistant and economical, but most of them only play a protective role and cannot prevent and control diseases that go deep into plants. Such as zinc sulfate, copper sulfate, carbendazim, chlorothalonil, green milk copper, surfactant, synergist, sulfur mixture, plant ash, Bordeaux mixture, mancozeb, thiram, chlorothalonil, etc. In addition, fungicides can also be classified according to the use method, such as seed treatment agent, soil disinfectant, spraying agent and so on. Protective fungicides mainly include the following categories: sulfur and inorganic sulfur compounds, such as sulfur suspending agent and solid stone sulfur mixture; Copper preparation, mainly Bordeaux solution, copper ammonia solution, etc. Organic sulfur compounds such as thiram, zineb, mancozeb, mancozeb, etc. Phthalimide, such as captan, Di Jun and bactericidal Dan; Antibiotics, such as validamycin, insecticide, adriamycin, etc. Other classes, such as Yekuling, Yekujing, Chlorothalonil, Hesuining, etc. Bactericides with early development history are all inorganic compounds, such as sulfur powder and copper preparation (see Bordeaux mixture), which have been used to this day. 19 14, I Rim Company of Germany used organic mercury compounds to control wheat smut for the first time, which marked the beginning of the development of organic fungicides. 1934, W.H. teasdale and others in the United States discovered the bactericidal characteristics of dimethyl dithiocarbamate, and then organic fungicides began to develop rapidly. In the 1940s and 1950s, there were three series of organosulfur fungicides: thiram, Dyson (such as zineb) and trichloromethylthiodicarboxylimide. In addition, organochlorine, organomercury and organoarsenic fungicide also developed. Most of these fungicides are protective agents, and their application is limited. Since 1960s, more and more chemical fungicides have appeared, the most important of which is systemic fungicide. 1965, organophosphorus fungicide Daowenjing developed in Japan, 1966, benomyl developed in the United States, 1967, thiophanate-methyl, Japan, 1969, Federal Republic of Germany, United States, 1975. The systemic agent represented by the above has become the mainstream of bactericide development since 1970s. At the same time, agricultural antibiotics have also developed rapidly. Organomercury, organoarsenic and some organochlorine fungicides are gradually eliminated due to toxicity or environmental pollution. The new generation of internal absorbents has further expanded the market of fungicides due to the improvement of control effect. By 1980s, there were more than 200 kinds of fungicides. According to the survey, in 1985, the global sales of fungicides reached 2.54 billion US dollars, accounting for 18.4% of the total sales of pesticides. 1984, sales of internal absorbent accounted for 44.2%, and non-internal absorbent accounted for 55.8%. In the past half century, the development of fungicides mainly focused on the drugs to prevent and treat fungal diseases, but the drugs to prevent and treat diseases caused by bacteria and viruses have not been sufficiently researched and developed. Since 1950s, China has mainly developed protective fungicides. Since 1970s, systemic fungicide and agricultural antibiotics have been developed, and the use of organic mercury has been stopped. Because of the complex application technology of fungicides, the development speed is not as fast as that of pesticides, but the protective effect of fungicides on agricultural production has been increasingly recognized by farmers. With the modernization of agriculture in China, the development of fungicides will be accelerated. Methods of use and operation There are many ways to use fungicides, and each method is designed according to the occurrence law of diseases. The common methods of use mainly include: field crop spraying, soil disinfection and seed bacteria disinfection. For spraying pesticides on field crops, the factors that affect the control effect of fungicides on field diseases are nothing more than chemicals, environment and crops, but the application technology of fungicides is more demanding than pesticides and herbicides, especially to fully understand the occurrence and development of diseases, because the occurrence and development of diseases are not as clear as pests and weeds. There are two points to pay attention to when spraying pesticides on field crops: the first is the type and concentration of pesticides. The choice of drugs depends on the type of disease, so we must make a correct diagnosis of the type of disease first, and then we can prescribe the right medicine. For example, rice blast can be selected from rice blast, rice blast, tricyclazole, etc. Triadimefon and triadimefon should be selected for wheat powdery mildew and rust, and thiophanate-methyl should be selected for peanut leaf spot. However, it should also be noted that if the same disease occurs on different crops, sometimes the same drug, such as Bordeaux mixture, can be used to control downy mildew, but it is easy to cause phytotoxicity to Chinese cabbage, so it is not suitable to control downy mildew of Chinese cabbage. After selecting the types of pesticides, it is also necessary to choose the appropriate application concentration according to the types and growth periods of crops, the types and dosage forms of fungicides, and environmental conditions. Methods to improve the efficacy of fungicides: both water and wettable powder drugs should be diluted with water before spraying. Different concentrations of fungicides have requirements, which need to be mixed in strict accordance with the instructions. Reasonable configuration concentration is more conducive to the effectiveness of fungicides. If mixed at will, too high concentration will cause phytotoxicity to crops; The concentration is too low to meet the control requirements. The suitable spraying time and spraying time of fungicides are directly related to the control effect. Spraying fungicides too early will waste chemicals and reduce the control effect. Too late pathogens have done harm to crops. Therefore, it is necessary to use drugs in time according to the occurrence law, prediction and specific conditions of different diseases. Generally speaking, the application time of fungicides can be selected before or at the early stage of onset. Improving the quality of drug use The quality of drug use of fungicides includes the quantity, frequency and quality of drug use. The dosage should be appropriate, too much medication will increase the cost and cause phytotoxicity, and too little medication will not achieve the prevention and control effect, and it should be increased or decreased according to the specific situation. The application frequency depends on the residual period and weather conditions. Generally, it is sprayed once every 10- 15 days and 2-3 times. If it rains after application, it needs to be sprayed again. The way to improve the quality of medicine is to spray the medicine evenly and carefully, and spray it all over the stems and leaves of plants. There are many reasons why fungicides cause phytotoxicity, including pesticides themselves, different crop sensitivities, crop growth stages and climatic conditions. Generally speaking, drugs and crops with strong water solubility are more likely to cause phytotoxicity at seedling stage, booting stage and flowering stage, such as high temperature, drought, fog and high humidity, which need to be handled carefully. Important functional bactericides have two modes of action: one is protective bactericide, and the other is systemic fungicide. Protective fungicides directly contact pathogenic bacteria in vitro or on the surface of plants, killing or inhibiting pathogenic bacteria from entering plants, thus protecting plants from the harm of pathogenic bacteria. This bactericide is called protective bactericide, which has two functions: first, contact with pathogenic bacteria after spraying directly kills pathogenic bacteria, that is, "contact sterilization"; The other is to spray chemicals on the surface of plants. When germs land on plants and come into contact with chemicals, they are poisoned. This is called "residual sterilization". Different bromogeramine fungicides act in different ways. When protective fungicides are applied to plant surfaces before infection, they are called protectants. Those that can destroy infected bacteria at the application site are called eradication fungicides; Systemic fungicide, which can be absorbed by plants and transmitted to the infected parts of bacteria in the body, is called "". Many eradicators are also systemic drugs, and most of them have chemotherapy effects. Therefore, in practice, fungicides are often simply divided into two modes of action: protective and systemic. Their mechanism of action can also be roughly divided into two categories: 1, which interferes with the respiratory process of bacteria and inhibits the production of energy. 2. Interfere with the biosynthesis of protein, nucleic acids, sterols and other biological substances. Most protective fungicides are products with broad bactericidal spectrum and low bactericidal power. Systemic fungicide generally has strong bactericidal power and narrow bactericidal spectrum, and some of them have specific selective toxicity to some pathogenic bacteria. Because the action point of systemic drugs in bacteria is relatively single, bacteria are prone to drug resistance due to gene mutation. In order to avoid or delay the emergence of drug resistance, appropriate protective agents and systemic agents can usually be mixed or used alternately to learn from each other's strengths and achieve better control effects. According to the characteristics of the disease, seed treatment, foliar spraying and soil treatment are adopted. 1 Application in industrial circulating cooling water In the field of industrial application, quaternary ammonium salt bactericides: dodecyl dimethyl benzyl ammonium chloride, dodecyl dimethyl benzyl ammonium bromide, tetradecyl dimethyl benzyl ammonium chloride, polyquaternary ammonium salt, etc. 2. Chlorine-containing bactericides: chlorine, chlorine dioxide, sodium dichloroisocyanurate (excellent chlorine), sodium trichloroisocyanurate, etc. 3. Peroxide bactericide: hydrogen peroxide, peracetic acid, etc. 4. Oxazoline: isothiazolinone, benzisothiazolinone, etc. 5. Application of aldehyde: glutaraldehyde, etc. In the water-based coating industry. Note: isothiazolinone, benzisothiazolinone, etc. Generally, the instructions for the use of pesticides have recommended concentrations, which can be used according to the instructions, but it is best to apply them according to the concentration proposed by the local plant protection technical department on the basis of efficacy tests. In dry or hot summer, the concentration should be reduced to avoid phytotoxicity. Secondly, when using fungicides, we should also pay attention to the duration and frequency of use. The key to master the application period is to master the occurrence and development law of diseases, make a good prediction of diseases, or prepare to spray fungicides according to the prediction of crop diseases by local plant protection departments. Generally speaking, fungicides are sprayed at the early stage of diseases, such as rice blast. Especially in hot weather when rice blast develops rapidly, it should be sprayed immediately. However, the development of peanut leaf spot disease is relatively slow, and it is not easy to spray drugs at the beginning of the disease, let alone before the disease, but when a certain development trend is formed after the disease. When the weather conditions are conducive to the rapid development of diseases, spraying must be started immediately, and sometimes spraying is necessary to control diseases when it rains in Mao Mao. Spraying period depends not only on the development law of diseases, but also on the growth period of crops. Many diseases are related to a certain growth stage of crops. In addition, attention should also be paid to the tolerance of crops to fungicides at various growth stages to prevent phytotoxicity. The occurrence and development of plant diseases often take a period of time, and it is difficult to solve the problem once by spraying fungicides, which often requires multiple spraying. The spraying times mainly depend on the reinfection of bacteria, the residual period of bactericide, climatic conditions, light, temperature and rainfall. Disinfection of seedlings. Seed soaking should use emulsion and solution, not suspension, that is, wettable powder. The key to seed soaking is the concentration of liquid medicine and soaking time. Improper operation will cause poor sterilization effect or phytotoxicity. Other factors, such as temperature, seed type and pathogen location, also affect the seed soaking effect. Under normal circumstances, after the seed type, temperature and drug type are determined, the drug concentration and seed soaking time can be coordinated, and the seed soaking time can be appropriately extended if the concentration is high. When the pathogen is deep or the seed coat is hard, the soaking time can be appropriately prolonged, and when the temperature is high, the soaking time can be shortened. Seed dressing requires that both seeds and powder must be dry, otherwise it will cause uneven seed dressing, produce phytotoxicity and affect the germination rate of seeds. Generally, the dosage of medicinal powder accounts for 0.2%~0.5% of the seed weight. When seed dressing, the powder and seeds should be added in 3~4 batches, and then the seed dressing container should be rotated appropriately to make it evenly mixed. After systemic fungicide appeared, a new seed dressing method-wet mixing method appeared. That is, wet the powder with a small amount of water first, and then seed dressing, or mix the dry powder on the wet seeds to make the powder stick to the surface of the seeds. After sowing, the drug slowly dissolves and is absorbed by plants and conducted upwards. Soil-borne diseases such as cotton Fusarium wilt and cucumber Fusarium wilt can be controlled by soil disinfection besides soaking or dressing seeds. In order to disinfect the soil, it is necessary to choose a suitable fungicide according to the disease type, and then choose a suitable soil treatment method according to the physical and chemical properties of the fungicide and the structure and properties of the soil. Irrigation method is suitable for water-soluble fungicides. After the concentration of bactericide is adjusted to a suitable level, about 5~ 10 kg of liquid medicine is poured on the ground per square meter. When the soil is dry, a lower concentration of liquid medicine can be used to increase the irrigation amount appropriately. When the soil is wet, high concentration and small flow irrigation can be used. The bactericide with high vapor pressure can be applied by plough bottom or furrow, that is, the medicinal powder or liquid medicine is evenly sprinkled on the furrow bottom of the first plough, and the medicine is covered by the second plough. This method is not suitable for the soil with too much viscosity. You can smear the powder or liquid medicine on the soil surface, and then turn it over and bury the medicine in the soil. Determination method The insecticidal or bactericidal toxicity of chemicals is often expressed as "lethal median dose", that is, the dose (mg/kg) required to kill half (50%) of biological population is often abbreviated as LD50. If concentration refers to dose, it is "lethal concentration", abbreviated as LC50. The bactericide is expressed by ED50 or EC50, that is, the dosage or concentration required to inhibit 50% spore germination. Spore germination measurement method: spray different liquid medicines on the surface of glass slide or plate, and add spore suspension quantitatively. After the liquid drug was exposed, the percentage of spore germination was examined by microscope after a certain culture time. The bacteriostatic circle method is to mix the suspension of pathogen spores or hyphae with agar medium, and after concentration, put a sterile circular filter paper (about 6 mm in diameter) soaked with different concentrations of liquid medicine on the culture medium plane. After a certain period of constant temperature culture, the growth of pathogenic bacteria is inhibited due to the diffusion of liquid medicine, that is, an "inhibition circle" is formed. The size of bacteriostatic circle was determined to compare the toxicity of fungicides. Growth rate determination method The method of adding liquid medicine to agar medium, concentrating and inoculating bacteria, after 24-48 hours, observing the growth of colonies, calculating the growth rate, and comparing with the growth rate of the control group without medicine. Development Prospect The market speed of active ingredients of pesticides is obviously slower than in the past, among which the decline speed of herbicides is the most obvious, and pesticides have also declined to a certain extent, while the market introduction of new fungicides is very strong, especially in recent years. In 2009, there were *** 17 new pesticide varieties, including 9 fungicides, accounting for more than 50%, including 3 amides, 3 strobilurins, triazolopyrimidine compounds 1 one, quinoline compounds 1 one and others 1 one. During the "Eleventh Five-Year Plan" period, 34 pesticide varieties with independent intellectual property rights in China obtained the pesticide registration license, including bactericide 17, accounting for half of the country. The main varieties are flumorph, dimethoxystrobin, pyraclostrobin and dimethoxystrobin. The reason why the global fungicide production and application prospects are promising is 1, that is, agricultural intensification; 2. It is the frequent occurrence of extreme weather that drives the demand of bactericide market; 3. The demand for fungicides in the non-pesticide field continues to grow at a high speed, with a large profit margin; 4. Some patents of high-efficiency fungicides will expire during the Twelfth Five-Year Plan period; 5. During the "Twelfth Five-Year Plan" period, the state will continue to encourage scientific and technological innovation, and constantly develop varieties of fungicides with independent intellectual property rights and put them on the market; 6. The growing area of genetically modified crops will have a great negative impact on pesticides and herbicides, but little impact on fungicides.