There are two ways of action of fungicides: one is a protective fungicide, and the other is a systemic fungicide. The protective fungicide directly contacts the pathogenic bacteria in vitro or on the surface of the plant, killing or inhibiting the pathogenic bacteria, making it unable to enter the plant, thereby protecting the plant from the pathogen. These fungicides are called protective fungicides. They have two functions: one is to contact the pathogen after spraying, and directly kill the pathogen, that is, “contact sterilizationâ€; the other is to spray the agent on the surface of the plant. In the above, when the pathogenic colony is exposed to the agent on the plant body and is poisoned, it is called "residual bactericidal effect". The protective fungicides mainly include the following types: sulfur and inorganic sulfur compounds, such as sulfur suspension agents, solid stone sulfur compounds, etc.; copper preparations, mainly Bordeaux liquid, copper ammonia mixture, etc.; organic sulfur compounds, such as thiram, Daisen Zinc, dexamethasone, mancozeb, etc.; phthalimide, such as captan, captan and sterilized Dan; antibiotics, such as Jinggangmycin, quercetin, polyoxymycin, etc.; Other types, such as Ye Kuling, Ye Kuojing, Baijingqing, Hesuining and so on.
The systemic fungicide is applied to a part of the crop body and can be absorbed by the crop and transported to other parts of the crop body. The fungicide with this property is called a "systemic fungicide". Systemic insecticides have two modes of conduction. One is apical conduction, that is, the drug is absorbed into the plant body and then transmitted to the top of the plant with transpiration to the top leaves, buds and leaves, and leaf margins. Most of the current systemic fungicides are of this type. The other is to conduct to the base, that is, the drug is absorbed by the plant body and then transmitted downward along the transport of the photosynthesis product in the phloem. Less of this type of systemic fungicide. Some fungicides such as ethyl phosphine oxide can be conducted in both directions. The systemic fungicides mainly include the following types: benzimidazoles, such as benomyl, carbendazim, thiabendazole, thiophanate and thiophanate; diimide, such as different bacteria Urea, ethylene nucleus, etc.; organic phosphorus, such as rice glutinous rice, glutinous rice, aluminum triethylphosphinate, etc.; phenyl amides, such as metalaxyl; sterol biosynthesis inhibitors, such sterilization The agents include tridemorpholine, oxazinamide, dinsetide, meconazole and ethyl pyridine, imazalil and imidate, triazol and triazolone, etc., from the chemical structure, they belong to morpholine, respectively. Pyroline, pyridine, pyrimidine, imidazole, 1,2,4-triazole compounds. The sterol synthesis inhibitor fungicide has both protective and therapeutic effects, and has a broad spectrum of sterilization.
The principle of bactericides for controlling plant diseases: Simply put, bactericides are compounds that have a toxic effect on pathogenic microorganisms. However, the term "sterilization" is not limited to "killing" the growth of pathogenic microorganisms or the two layers of spore germination. The fungicide capable of killing the pathogenic microorganism can play a bactericidal action, and can inhibit the bactericidal action of the spore germination or growth of the pathogen, and both of the effects can achieve the purpose of preventing disease and treating diseases in agricultural production. The action of fungicides is different, and the methods of use are also different, but fundamentally, the principle of fungicides to control diseases is nothing more than three kinds of chemical protection, chemical treatment and chemical immunity.
Chemical protection is the spraying of fungicides to prevent the occurrence of plant diseases before the plants are sick. There is a meaning of "the rabbit is not seen before the eagle." Some of the common fungicides have only two protective measures: one is to remove the source of infection at the source of the pathogen. The source of the pathogen is mainly the place where the bacteria overwinter, the intermediate host and the soil. The purpose of eliminating or reducing the source of infestation by the application of a bactericide is to reduce the likelihood of infection of the crop by the pathogen. For example, in winter, weeding weeds in orchards and eliminating wintering bacteria; specific means such as disinfection of bacteria and soil disinfection are such chemical protection measures. The second is to spray a fungicide on the crops that are not infected in the field and may be infected by the pathogens to prevent pathogen infection. After spraying the fungicide on the surface of the crop, it can kill the pathogenic cells or spores that infect the crop. In order to control the infestation of crops by soil-borne pathogens, it is a measure to treat crop seeds with fungicides before planting or to treat seedling roots with fungicides before transplanting.
Chemotherapy is "seeing the rabbit square eagle." That is, the bactericide is applied to the protected crop or to the pathogen after the plant is infected or susceptible, and the pathogenic process of the pathogen is changed, thereby achieving the purpose of reducing or eliminating the disease. Prevention is more important than treatment, and the effect of preventing disease is better than that of treating diseases. Therefore, the plant protection policy of “prevention-based, comprehensive prevention†proposed by China's plant protection science and technology workers is very instructive. Chemotherapy can be divided into three types according to the degree of infection of the pathogen and the mode of administration: one is surface chemistry. Some pathogens, such as powdery mildew, are mainly attached to the surface of plants. Stone sulphur can kill germs and provide surface treatment. Non-systemic fungicides can prevent such diseases. One is internal chemotherapy, which introduces a fungicide into the body of the crop to treat germs that have invaded the interior of the plant. Only systemic insecticides such as methyl thiophanate and carbendazim have internal chemotherapeutic effects. The effect of internal treatment of systemic fungicides is twofold: on the one hand, it is directly toxic to the pathogen; on the other hand, it changes the metabolism of the plant, and changes its response to the pathogen or the pathogenic process of the pathogen. However, most systemic fungicides have only one of them, and some fungicides have two effects. One is external chemotherapy, which is often used in the control of fruit trees or forest diseases. It is external chemotherapeutic treatment. It is to scrape the diseased spots on the outside of the trunk or branches infected by pathogens, and the wounds are disinfected with fungicides. Apply a protective or water repellent to prevent further spread of infection.
Chemical immunization is the use of chemicals to give protected crops resistance to pathogens. The compounds with chemical immunological functions that are relatively positive at present are three compounds such as 2,2-dichloro-3,3-dimethylcyclopropanecarboxylic acid, ethylphosphonium bromide and thiazolazole. Among them, thiazolidine is the most typical chemical immunizing agent. It can be used to treat rice plants to induce several antibacterial substances to make rice resistant to rice blast.
There are many ways to use fungicides, and each method of use is designed according to the law of disease occurrence. The common methods of use are: spraying the crops on the ground, disinfecting the soil and disinfecting the inoculum.
For the field crop spraying, the factors affecting the field defense effect of the fungicide are not only the three aspects of the agent, the environment, and the crop, but the application technology of the fungicide is higher than the application technology of the insecticide and the herbicide, especially It is necessary to fully understand the law of the occurrence and development of diseases, because the occurrence and development of diseases are not as clear as pests and grasses. There are two points to note about spraying crops in the field: first, the type and concentration of the agent. The choice of the type of the drug depends on the type of disease, so it is necessary to make a correct diagnosis of the type of disease before it can be prescribed. For example, rice blast can be selected from rice glutinous rice, rice glutinous rice, tricyclazole, wheat powdery mildew, rust, triazolol, triadimefon, etc., and peanut leaf spot should be selected from methyl thiophanate. However, it should also be noted that if the same disease occurs on different crops, sometimes the same agent cannot be used. For example, Bordeaux mixture can prevent downy mildew, but it is easy to cause phytotoxicity to cabbage, so it is not suitable for controlling cabbage downy mildew. After the type of the drug is selected, an appropriate application concentration is selected according to the type of the crop and the growth period, the type of the bactericide, the dosage form, and the environmental conditions. The general pesticide instruction manual has recommended concentrations, which can be used according to the instructions, but it is best to apply according to the concentration used by the local plant protection technical department based on the efficacy test. In dry or hot summers, the concentration should be reduced to avoid phytotoxicity. Secondly, when using the fungicide, pay attention to the period of use and the number of uses. The key to mastering the spraying period is to master the law of disease occurrence and development, to predict the forecast of disease occurrence, or to predict the crop disease according to the local plant protection department. It is predicted to prepare for spraying the fungicide. Under normal circumstances, the spraying of fungicides is carried out in the early stage of the disease, such as rice blast, especially in high temperature weather, rice blast develops rapidly, and should be sprayed immediately. However, the development of peanut leaf spot disease is relatively slow. Do not spray easily when the disease is on, and it is not possible to spray before the onset of the disease, but to start spraying when a certain development trend is formed after the onset of the disease. The climatic conditions are conducive to the rapid development of the disease, and should be sprayed immediately. Sometimes, in order to control the disease, it is necessary to spray the medicine when it is drizzling. The spraying period is determined by the law of disease development, and the growth period of the crop is also taken into consideration. Many diseases occur in connection with a certain growth stage of the crop. In addition, attention should also be paid to the tolerance of the fungicides during the growth period of the crops to prevent phytotoxicity. The occurrence and development of plant diseases often takes a while, and it is difficult to solve the problem once by spraying the fungicide. It often needs to be sprayed several times. The number of sprays is mainly determined by the reinfection of the bacteria, the residual period of the fungicide, as well as climatic conditions, light, temperature and rainfall.
Seedling disinfection. For soaking seeds, use emulsions and solutions. Do not use suspensions. Wet powders should not be used for soaking seeds. The key to soaking seeds is the concentration of the liquid and the time of soaking. Improper handling can result in poor sterilization or phytotoxicity. Other factors such as temperature, seed type, and the location of the pathogen also affect the soaking effect. Under normal circumstances, after the seed type, temperature, and drug type are determined, the concentration of the drug and the soaking time can be coordinated, and the high concentration can appropriately prolong the soaking time. If the pathogen is deep or the seed coat is hard, the soaking time can be extended appropriately. The high temperature can shorten the soaking time. Seed dressing and powder must be dry when seed dressing, otherwise it will cause uneven seed dressing, produce phytotoxicity, and affect the germination rate of seeds. The dosage of the powder generally accounts for 0.2%~0.5% of the weight of the seed. When the seed is mixed, the medicament and the seed are divided into 3~4 batches, and then the seed dressing container is appropriately rotated to make it evenly mixed. After the emergence of systemic fungicides, a new method of seed dressing, wet mixing, has emerged in recent years. That is, the powder is wetted with a small amount of water, and then seeded, or the dried powder is mixed on the wet seeds, so that the powder adheres to the surface of the seed. After being sown, the medicament is slowly dissolved and absorbed into the plant to conduct upward.
Soil-borne diseases such as cotton wilt and cucumber wilt may be controlled by soil disinfection, in addition to being controlled by soaking or seed dressing. Soil disinfection should first select the appropriate fungicide according to the type of disease, and then select the appropriate soil treatment method according to the physical and chemical properties of the drug and the soil structure and properties. The watering method is suitable for the water-soluble bactericide. After adjusting the medicinal agent to the appropriate concentration, watering about 5~10 kg of liquid per square meter of ground can be used. When the soil is dry, a lower concentration of the liquid can be used, and the watering volume is appropriately increased. When the soil is wet, high-concentration and small-volume watering can be used. The bactericide with higher vapor pressure can be applied by plowing or furrow, that is, the powder or liquid is evenly sprinkled into the bottom of the first plough, and the soil is covered by the soil of the second plough. This method is not suitable. For heavy soil, the powder or liquid can be applied to the surface of the soil, and then the soil is buried in the soil.
The systemic fungicide is applied to a part of the crop body and can be absorbed by the crop and transported to other parts of the crop body. The fungicide with this property is called a "systemic fungicide". Systemic insecticides have two modes of conduction. One is apical conduction, that is, the drug is absorbed into the plant body and then transmitted to the top of the plant with transpiration to the top leaves, buds and leaves, and leaf margins. Most of the current systemic fungicides are of this type. The other is to conduct to the base, that is, the drug is absorbed by the plant body and then transmitted downward along the transport of the photosynthesis product in the phloem. Less of this type of systemic fungicide. Some fungicides such as ethyl phosphine oxide can be conducted in both directions. The systemic fungicides mainly include the following types: benzimidazoles, such as benomyl, carbendazim, thiabendazole, thiophanate and thiophanate; diimide, such as different bacteria Urea, ethylene nucleus, etc.; organic phosphorus, such as rice glutinous rice, glutinous rice, aluminum triethylphosphinate, etc.; phenyl amides, such as metalaxyl; sterol biosynthesis inhibitors, such sterilization The agents include tridemorpholine, oxazinamide, dinsetide, meconazole and ethyl pyridine, imazalil and imidate, triazol and triazolone, etc., from the chemical structure, they belong to morpholine, respectively. Pyroline, pyridine, pyrimidine, imidazole, 1,2,4-triazole compounds. The sterol synthesis inhibitor fungicide has both protective and therapeutic effects, and has a broad spectrum of sterilization.
The principle of bactericides for controlling plant diseases: Simply put, bactericides are compounds that have a toxic effect on pathogenic microorganisms. However, the term "sterilization" is not limited to "killing" the growth of pathogenic microorganisms or the two layers of spore germination. The fungicide capable of killing the pathogenic microorganism can play a bactericidal action, and can inhibit the bactericidal action of the spore germination or growth of the pathogen, and both of the effects can achieve the purpose of preventing disease and treating diseases in agricultural production. The action of fungicides is different, and the methods of use are also different, but fundamentally, the principle of fungicides to control diseases is nothing more than three kinds of chemical protection, chemical treatment and chemical immunity.
Chemical protection is the spraying of fungicides to prevent the occurrence of plant diseases before the plants are sick. There is a meaning of "the rabbit is not seen before the eagle." Some of the common fungicides have only two protective measures: one is to remove the source of infection at the source of the pathogen. The source of the pathogen is mainly the place where the bacteria overwinter, the intermediate host and the soil. The purpose of eliminating or reducing the source of infestation by the application of a bactericide is to reduce the likelihood of infection of the crop by the pathogen. For example, in winter, weeding weeds in orchards and eliminating wintering bacteria; specific means such as disinfection of bacteria and soil disinfection are such chemical protection measures. The second is to spray a fungicide on the crops that are not infected in the field and may be infected by the pathogens to prevent pathogen infection. After spraying the fungicide on the surface of the crop, it can kill the pathogenic cells or spores that infect the crop. In order to control the infestation of crops by soil-borne pathogens, it is a measure to treat crop seeds with fungicides before planting or to treat seedling roots with fungicides before transplanting.
Chemotherapy is "seeing the rabbit square eagle." That is, the bactericide is applied to the protected crop or to the pathogen after the plant is infected or susceptible, and the pathogenic process of the pathogen is changed, thereby achieving the purpose of reducing or eliminating the disease. Prevention is more important than treatment, and the effect of preventing disease is better than that of treating diseases. Therefore, the plant protection policy of “prevention-based, comprehensive prevention†proposed by China's plant protection science and technology workers is very instructive. Chemotherapy can be divided into three types according to the degree of infection of the pathogen and the mode of administration: one is surface chemistry. Some pathogens, such as powdery mildew, are mainly attached to the surface of plants. Stone sulphur can kill germs and provide surface treatment. Non-systemic fungicides can prevent such diseases. One is internal chemotherapy, which introduces a fungicide into the body of the crop to treat germs that have invaded the interior of the plant. Only systemic insecticides such as methyl thiophanate and carbendazim have internal chemotherapeutic effects. The effect of internal treatment of systemic fungicides is twofold: on the one hand, it is directly toxic to the pathogen; on the other hand, it changes the metabolism of the plant, and changes its response to the pathogen or the pathogenic process of the pathogen. However, most systemic fungicides have only one of them, and some fungicides have two effects. One is external chemotherapy, which is often used in the control of fruit trees or forest diseases. It is external chemotherapeutic treatment. It is to scrape the diseased spots on the outside of the trunk or branches infected by pathogens, and the wounds are disinfected with fungicides. Apply a protective or water repellent to prevent further spread of infection.
Chemical immunization is the use of chemicals to give protected crops resistance to pathogens. The compounds with chemical immunological functions that are relatively positive at present are three compounds such as 2,2-dichloro-3,3-dimethylcyclopropanecarboxylic acid, ethylphosphonium bromide and thiazolazole. Among them, thiazolidine is the most typical chemical immunizing agent. It can be used to treat rice plants to induce several antibacterial substances to make rice resistant to rice blast.
There are many ways to use fungicides, and each method of use is designed according to the law of disease occurrence. The common methods of use are: spraying the crops on the ground, disinfecting the soil and disinfecting the inoculum.
For the field crop spraying, the factors affecting the field defense effect of the fungicide are not only the three aspects of the agent, the environment, and the crop, but the application technology of the fungicide is higher than the application technology of the insecticide and the herbicide, especially It is necessary to fully understand the law of the occurrence and development of diseases, because the occurrence and development of diseases are not as clear as pests and grasses. There are two points to note about spraying crops in the field: first, the type and concentration of the agent. The choice of the type of the drug depends on the type of disease, so it is necessary to make a correct diagnosis of the type of disease before it can be prescribed. For example, rice blast can be selected from rice glutinous rice, rice glutinous rice, tricyclazole, wheat powdery mildew, rust, triazolol, triadimefon, etc., and peanut leaf spot should be selected from methyl thiophanate. However, it should also be noted that if the same disease occurs on different crops, sometimes the same agent cannot be used. For example, Bordeaux mixture can prevent downy mildew, but it is easy to cause phytotoxicity to cabbage, so it is not suitable for controlling cabbage downy mildew. After the type of the drug is selected, an appropriate application concentration is selected according to the type of the crop and the growth period, the type of the bactericide, the dosage form, and the environmental conditions. The general pesticide instruction manual has recommended concentrations, which can be used according to the instructions, but it is best to apply according to the concentration used by the local plant protection technical department based on the efficacy test. In dry or hot summers, the concentration should be reduced to avoid phytotoxicity. Secondly, when using the fungicide, pay attention to the period of use and the number of uses. The key to mastering the spraying period is to master the law of disease occurrence and development, to predict the forecast of disease occurrence, or to predict the crop disease according to the local plant protection department. It is predicted to prepare for spraying the fungicide. Under normal circumstances, the spraying of fungicides is carried out in the early stage of the disease, such as rice blast, especially in high temperature weather, rice blast develops rapidly, and should be sprayed immediately. However, the development of peanut leaf spot disease is relatively slow. Do not spray easily when the disease is on, and it is not possible to spray before the onset of the disease, but to start spraying when a certain development trend is formed after the onset of the disease. The climatic conditions are conducive to the rapid development of the disease, and should be sprayed immediately. Sometimes, in order to control the disease, it is necessary to spray the medicine when it is drizzling. The spraying period is determined by the law of disease development, and the growth period of the crop is also taken into consideration. Many diseases occur in connection with a certain growth stage of the crop. In addition, attention should also be paid to the tolerance of the fungicides during the growth period of the crops to prevent phytotoxicity. The occurrence and development of plant diseases often takes a while, and it is difficult to solve the problem once by spraying the fungicide. It often needs to be sprayed several times. The number of sprays is mainly determined by the reinfection of the bacteria, the residual period of the fungicide, as well as climatic conditions, light, temperature and rainfall.
Seedling disinfection. For soaking seeds, use emulsions and solutions. Do not use suspensions. Wet powders should not be used for soaking seeds. The key to soaking seeds is the concentration of the liquid and the time of soaking. Improper handling can result in poor sterilization or phytotoxicity. Other factors such as temperature, seed type, and the location of the pathogen also affect the soaking effect. Under normal circumstances, after the seed type, temperature, and drug type are determined, the concentration of the drug and the soaking time can be coordinated, and the high concentration can appropriately prolong the soaking time. If the pathogen is deep or the seed coat is hard, the soaking time can be extended appropriately. The high temperature can shorten the soaking time. Seed dressing and powder must be dry when seed dressing, otherwise it will cause uneven seed dressing, produce phytotoxicity, and affect the germination rate of seeds. The dosage of the powder generally accounts for 0.2%~0.5% of the weight of the seed. When the seed is mixed, the medicament and the seed are divided into 3~4 batches, and then the seed dressing container is appropriately rotated to make it evenly mixed. After the emergence of systemic fungicides, a new method of seed dressing, wet mixing, has emerged in recent years. That is, the powder is wetted with a small amount of water, and then seeded, or the dried powder is mixed on the wet seeds, so that the powder adheres to the surface of the seed. After being sown, the medicament is slowly dissolved and absorbed into the plant to conduct upward.
Soil-borne diseases such as cotton wilt and cucumber wilt may be controlled by soil disinfection, in addition to being controlled by soaking or seed dressing. Soil disinfection should first select the appropriate fungicide according to the type of disease, and then select the appropriate soil treatment method according to the physical and chemical properties of the drug and the soil structure and properties. The watering method is suitable for the water-soluble bactericide. After adjusting the medicinal agent to the appropriate concentration, watering about 5~10 kg of liquid per square meter of ground can be used. When the soil is dry, a lower concentration of the liquid can be used, and the watering volume is appropriately increased. When the soil is wet, high-concentration and small-volume watering can be used. The bactericide with higher vapor pressure can be applied by plowing or furrow, that is, the powder or liquid is evenly sprinkled into the bottom of the first plough, and the soil is covered by the soil of the second plough. This method is not suitable. For heavy soil, the powder or liquid can be applied to the surface of the soil, and then the soil is buried in the soil.
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