Crop Bacterial Diseases and Prevention Technology Program

Crop Bacterial Diseases and Prevention Technology Program

Bacterial diseases are diseases caused by bacterial infections, such as soft rot, ulcer disease, bruising, and the like. Bacterial diseases are important diseases that affect China's agricultural production.

There are about 500 kinds of bacterial crop diseases worldwide, and there are 60-70 kinds of major bacterial crop diseases in China.

Bacterial diseases often cause serious losses, and it is estimated that potatoes are reduced by 25% annually due to bacterial diseases.

In order to increase crop yield and quality, the control of plant diseases is particularly important.

Therefore, from a general perspective, it is necessary to make an overview of bacterial diseases. This article will initially discuss this.

I. Introduction to important bacterial genera and representative species

At present, the phytopathogenic bacteria belong to the genus Proteobacteria of the genus Firmamentaris and the phylum Laminaria, with a total of 25 genera, 115 species, 17 subspecies and 217 pathogenic species. However, there are seven of the most common and important bacterial genera, including Xanthomonas, Pseudomonas, Escherichia, Bacillus, Corynebacterium, and Rostonia.

1, Xanthomonas

Xanthomonas is a member of the phylum. The bacteria are short-barreled, more solitary, less twin, single flagellate, extremely polar, Gram-negative, negative and strict. Xanthomonas bacteria are plant pathogens. The plant diseases caused by it spread all over the world, such as rice bacterial leaf blight, rice bacterial leaf streak disease, Karma jaundice pathology, citrus canker disease, cruciferous vegetables black rot and cotton leaf spot disease. This genus bacterium currently contains 6 species, namely, Xanthomonas campestris, Xanthomonas oryzae, Xanthomonas lanobensis, Xanthococcus luteus, Xanthomonas or Xanthomonas oryzae. The Xanthomonas campestris includes 140 pathogenic species.

2. Pseudomonas

Pseudomonas is a model genus of Pseudomonas: a short rod-shaped, solitary, flagella 1–4, extremely polar; Gram negative reaction, strict aerobic, metabolic respiratory. Some species produce water-soluble fluorescent pigments. The oxidase reaction was generally negative, with a few positive, and the catalase reaction was positive. Some species of Pseudomonas are important plant pathogens, such as Pseudomonas syringae is an important plant pathogenic bacteria. Its host range is extremely wide, and can infect many kinds of woody plants and herbs, cause leaf spots or necrosis and stem cankers and other symptoms. Pseudomonas syringae includes 41 pathogenic species.

3, Erwinia

Erwinia is a member of the family Enterobacteriaceae. The bacteria are short-barreled, with multiple twins, short chains, and even solitary, flagellate weeks. Gram-negative reaction was negative, facultative aerobic, metabolic to respiratory or fermentation. Most Erwinia species are phytopathogenic bacteria. Caused by plant necrosis, ulcers, wilting, leaf spots, flow plastic and soft rot and other symptoms. According to the characteristics of parasitic and pathogenicity, combined with physiological and biochemical indicators, the genus can be divided into two groups. The first group is the amyloplast group, and the other group is a carrot soft rot group, which includes a total of 17 species. . The important pathogenic bacteria in the amylolytic group were E. amylovora; carrot soft rot bacteria and Erwinia chrysanthemi in carrot soft rot were the common and important pathogens. The genus Pantoea was established based on the bacterium belonging to the genus Erwinia.

4. Agrobacterium

The Agrobacterium genus is a member of the Rhacobacteriaceae family. Bacteria short rod-like. Single cattle or twins, 1-6 flagella, week or lateral, no spores, good air. Metabolism is respiratory type, Gram negative reaction, negative oxidase reaction, positive catalase reaction. Agrobacterium contains 4 species, among which Agrobacterium tumefaciens and A. rhizogenes are important plant pathogens. They contain oncogenic plasmids and hair rooting plasmids, respectively, causing abnormalities such as crown gall tumors and hair roots.

5, Corynebacterium

The genus Corynebacterium was established by the former Corynebacterium genus, belonging to the genus Firmarum. The cells were short to irregular, with no flagella, no spores, Gram positive reaction, aerobic, metabolically respiratory, negative oxidase reactions, and positive catalase reactions. The genus Corynebacterium contains 5 species and 7 subspecies, among which C. miliata is a model species, and includes potato rot, sub-species of phalaenopsis, subspecies of mosaic, Nebraska subspecies and Michigan subspecies. Potatoes infected with Corynebacterium circulans infested 5 kinds of Solanum plants.

6. Phytobacter

The phloem genus is a newly established genus and is a type of bacterium that infests the phloem of plants. It is represented by pathogenic bacteria of citrus yellow dragon disease. This type of bacteria has not yet been purely cultivated. Under the electron microscope, the morphology of the H. solanacearum strains was fusiform in short rods, Gram-negative responses were negative, and Bacillus bacillus included 2 species. They are the yellow turmeric pathogens that occur in Asia and the citrus bacterium pathogens that occur in Africa.

7. Streptomyces

Streptomyces is a class of high-grade bacteria that combines both bacterial and fungal traits. It grows in the air into filamentous branched filaments of slender filaments, and some branches break into many short rod-shaped bacteria such as fungal powders. Spores, sheathing at the time of rupture, bacteria do not move, Gram stain reaction positive. This is an important pathogenic bacteria, such as potato acne disease, the disease caused by acne disease in China and Europe, the United States and other places, the main potato disease. This bacterium stimulates local tissue hyperplasia and paraffinization of the epidermal cells of the host and forms helium, which affects yield and quality. The fungus grows in alkaline, moist soils containing organic matter.

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B. Parasitic nature of plant pathogenic bacteria

The parasitic nature of the plant pathogens found so far can be divided into two categories.

The first type of bacteria are facultative parasites that can both parasite and grow on the medium. The parasitic ability of these bacteria is different, and the bacteria with strong parasitic ability can damage the green part of the plant.

If the parasitic ability is weak, it mainly damages the storage organs and weak resistance parts of the plants, or can only be immersed in the host body under certain conditions;

Plant pathogenic bacteria, which are highly parasitic, can mostly survive in living plant tissues or unresolved plant debris, but they can quickly die in soil or water.

For example, Bacterial blight bacterial and cotton leaf spot pathogenic bacteria are not easy to overwinter in the soil, while the vegetable soft rot bacteria are able to overwinter in the soil.

The phytopathogenic bacteria with strong saprophytic ability, although they can survive for a long time outside the plant, cannot reproduce in large numbers and may soon lose their pathogenicity and maintain their viability. Bacteria belonging to this group include bacterial wilt and crown gall bacteria.

The second type of bacteria is a parasite that cannot be cultivated artificially. This type of bacteria contains X. sclerotiorum, phloem bacteria, and phytoplasma. Plant pathogenic bacteria have a certain range of hosts, some species have a wide range of hosts, and some species have a narrow host.

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III. Pathogenicity, dissemination and spread of phytopathogenic bacteria

1, pathogenicity

Pathogenicity is the characteristic that the pathogenic bacteria cause damage to the host when establishing a parasitic relationship on the plant. Parasitism and pathogenicity are two different traits. Rhizobium disease and Pseudomonas fluorescens and plants can establish a parasitic relationship, but generally do not cause harmful diseases to plants. The bacterial rot of Chinese cabbage is weak, but it causes severe rot during the storage period.

2, dip dyeing route

The invasion of plants by plant pathogenic bacteria is a passive intrusion, that is, they cannot form invasive structures when they invade, but can only invade from natural orifices and wounds. Stoma, water holes, skin wood (holes), and nectaries are natural holes that bacteria invade. mouth. Infestation of Spodoptera fissa from the stomata causes angular spot disease. Invasion of stomata and lenticels caused by citrus canker and mulberry pathogens caused citrus canker and mulberry diseases. Xanthomonas oryzae invaded through rice leaf pores; E. amylovora invaded through the nectaries.

Wind, hail, frost damage, insects, nematodes, and other natural factors as well as various agricultural operations such as ploughing, fertilizing, grafting, harvesting, and transportation are also excellent ways for bacteria to invade. In general, bacteria invading from natural orifices can invade through wounds, whereas bacteria invading from wounds cannot necessarily establish parasitic relationships with plants from natural orifices. For example: Chinese cabbage soft rot bacterium and Agrobacterium tumefaciens can only invade from the wound, rarely invade from the natural orifice.

Parasitic bacteria are generally invasive from the wound; and highly parasitic bacteria can invade from the wound, but also from the natural orifice. In the group of important plant pathogenic bacteria, Pseudomonas and Xanthomonas bacteria mainly invaded by natural orifices. The bacteria belonging to the genus Agrobacterium, Corynebacterium, and Erwinia are mainly invaded by wounds, and the phlebobacteria, phytoplasma, and spiroplasma are invaded by wounds caused by insect feeding.

The distribution of plant pathogenic bacteria in plants can be divided into two types: local distribution and systematic distribution.

The former bacteria are confined to parenchyma, spread through cells, and multiply in dead cells, leading to localized lesions such as leaf spots, rot and tumors;

The latter bacteria enters the vascular tissue through parenchyma or water holes, mainly spreading in the xylem or phloem of vascular tissue. The bacterial wilt fungus was propagated and spread in the xylem to acquire wilting symptoms. The Xanthomonas oryzae cultivars are slow to propagate and spread in parenchyma cells and can only form local spots. After entering the vascular tissue, they quickly spread along the veins and form long-formed leaves.

3, the transmission route

Plant pathogenic bacteria are transmitted through rainwater, mediator organisms, seedlings, and grafts. Bacteria multiply in plant tissues and exude to the surface of the plant in the form of pyoderma. Splashes of rain and water droplets cause bacteria to spread from plant to plant. Therefore, the severity of many plant bacterial diseases is closely related to the amount of rainfall. In addition, pathogenic bacteria can only successfully invade plants in the presence of water.

The biological mediators that transmit pathogenic bacteria are insects and nematodes. Maize bacterial wilt pathogens can be transmitted by many kinds of insects, among them, corn columb is the main mediator of infection; yellow striped triceps, adult pods, green leaves, diamondback moth, vegetable larvae, and leafhopper larvae can carry and Spread the cabbage soft rot bacteria; bees are the important mediators of the epidemic of pear fire; the mediator of citrus yellow globus disease is hibiscus. In the nematode mediators, it is relatively certain that wheat grain nematodes transmit wheat ear disease. In addition, nematodes and some pathogenic bacteria such as bacterial wilt, Corynebacterium form a complex pathogen.

Some phytopathogenic bacteria can pass through winter and summer over the seeds or vegetative propagation materials (roots, tubers, bulbs), and spread with the transfer of seeds and seedlings. Xanthomonas oryzae, citrus canker, potato ring rot, sweetpotato disease, etc. can all be spread long distances through the proliferation of seedlings. Phytoplasma, xylem bacillus, and phloem bacillus can be infected by grafting and spread long distances by grafting. The application of unfertilized fertilizer containing these pathogens can also be transmitted to disease-free fields. Other pathogenic bacteria have a shorter survival period in the soil, but they can survive in sick tissues. The pathogenic bacteria in the diseased body have a longer survival period under low temperature and dry conditions. Therefore, proper treatment of sick tissues can inhibit the spread of pathogenic bacteria.

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IV. Ecological factors affecting the occurrence of plant pathogenic bacteria

1, pathogenic bacteria itself

The genetic constitution and variation mechanism of the pathogenic bacterial population have an impact on the occurrence of bacteria. Non-toxic or attenuated strains producing bacteriocins were found in the Xanthomonas, Agrobacterium, Pseudomonas, and E. coli populations. Experiments have shown that the Agrobacterium tumefaciens K84 strain has a significant inhibitory effect on Agrobacterium tumefaciens infection, and has been registered in many countries as a biocontrol agent K84 has a competitive mechanism and produces the bacteriocin Agrocin84.

2, plant factors

The resistance of plants to pathogenic bacteria affects both the size of the population of pathogenic bacteria. At the same time, it also influences the group toxicity of the pathogenic bacteria. In many plant-pathogenic bacterial interaction systems, the difference in resistance between plant varieties is significant. For example, there are varieties (lines) in rice resistant to Xanthomonas and Bacteria, but there are a few plants. The resistance of plants in the bacterial system is not obvious. For example, the plants have little resistance to Ralstonia solanacearum and Agrobacterium tumefaciens and the difference between the varieties is small. At present, it has been proved that the interaction between some species of Xanthomonas and Pseudomonas and the plants conforms to the "gene-to-gene" hypothesis.

3, environmental factors

The first is environmental biological factors. Mediator organisms have spread the pathogenic bacteria mentioned above. It is discussed here that the parasites of bacteria are bacterial viruses (phage) and solitary bacteria.

Bacteriophages can cause the destruction of bacteria and form plaques on the colonies. Using the relationship between bacteriophage and bacteria can predict the amount of bacteria. China is more successful in using bacteriophage to predict bacterial blight in rice. Others are also studying the use of bacteriophages to control bacterial diseases.

Thallium is a kind of micro-gram-negative bacteria that swims very fast. When it comes into contact with the host bacteria, it rotates at high speed into bacteria, and makes the host bacteria become "empty shell" within 1-24 hours. The common host is G bacteria such as Pseudomonas syringae. Under the controlled conditions, the scorpion bacterium has control effect on some bacterial diseases. There are many types of microorganisms that have antibiotic effects on bacteria in the soil and plant environment. Certain strains and strains of Pseudomonas fluorescens in the bacteria, and some strains of certain panicle-producing bacteria of Bacillus can inhibit some pathogenic bacteria. Paecilomyces, Penicillium, Trichoderma and Gliocladium spp. in fungi (can produce some antibacterial antibiotics; Streptomyces produced by streptomycin and tetracycline have obvious control effect on bacteria and phytoplasma caused diseases.

Second, the physical and chemical factors in the environment such as temperature, humidity and moisture have an impact on the occurrence of bacteria.

The optimum temperature for the growth of plant pathogenic bacteria is generally around 26-30°C. With a few exceptions, the optimum temperature for the growth of P. solanacearum is 35°C, and the optimum temperature for the growth of C. circulans is 20-23°C. Humidity and moisture affect the spread and infestation of pathogenic bacteria on the one hand and the survival of bacteria on the other.

The survival of many pathogenic bacteria in the soil depends on the remnant tissue of the plant.

Under high temperature and high humidity, residual tissue decomposition and rot can be promoted, and the survival of bacteria is unfavorable. Soil habitual pathogenic bacteria such as Bacteroides solanacearum, Agrobacterium tumefaciens and Streptozotocin are aerobic bacteria. High-humidity soils will inevitably affect soil aeration and reduce its survival.

Ventilation conditions have different effects on different pathogenic bacteria. For aerobic bacteria, good ventilation results in their survival and infestation, but for facultative bacteria such as Erwinia carotovora, it is most suitable for anaerobic conditions. Infection and symptoms.

Field distribution.

In the early stage of field distribution, diseased plants had epidemic centers, which spread along the direction of water flow, low-lying terrain, deep-water irrigation, greenish seedlings, and aggravated disease after severe storms and human- and insect-infested wounds.

Crop cultivation and management measures also have a significant impact on the occurrence of pathogenic bacteria. Through selection and promotion of anti-resistant (resistant) varieties, reasonable rotation, intercropping and timely sowing, and reasonable fertilization measures can be used to create a microclimate conducive to plants that are not conducive to pathogenic bacteria, so as to inhibit the occurrence of pathogenic bacteria.

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V. Identification of Plant Bacterial Diseases

In the large family of plants that identify bacterial diseases, the types of diseases caused by fungal infections are the most, followed by the diseases caused by the original bacteria. To effectively prevent and treat bacterial diseases, it is necessary to understand the characteristics of bacterial diseases, and to grasp the correct diagnosis and identification. Technology can achieve the right remedy.

1, the disease caused by plants infected with bacteria

(1) Spot type: Diseases caused by Pseudomonas infestation in plants, and a considerable amount of oceanography was spotted. Such as bacterial brown spot in rice, cucumber bacterial leaf spot disease, cotton bacterial leaf spot disease and so on.

(2) Leaf blight type: Most of them are caused by infection with Xanthomonas and eventually the leaves will wither. Such as rice bacterial blight, cucumber bacterial leaf blight, konjac bacterial leaf blight and so on.

(3) Green and dry type: In general, Pseudomonas spp. invades the vascular bundles of plants, obstructs the transmission pathway, and causes stems and leaves of the plants to wither. Such as tomato bacterial wilt, potato blight, strawberry bacterial wilt and so on.

(4) ulcer type: generally caused by Erwinia of the genus Xanthomonas, the latter stage of wood thrombosis, the edge of the uplift, the central depression was ulcerated. Such as citrus canker, vegetable soybean bacterial blight, bacterial fruit bacterial leaf spot disease.

(5) Rotten type: Most rot caused by infection with plants of Erwinia. Such as bacterial bacterial soft rot disease, Solanaceae and cucurbitaceous crop bacterial soft rot, and rice-based rot.

(6) Malformation: It is caused by the infection of the bacillus cerevisiae, which causes the roots and roots of the plants to become malformed on the lateral roots as well as on the stems. Such as chrysanthemum root cancer disease.

2, disease characteristics and identification methods

The above types of pathological conditions and plant fungal diseases also have similar performances, but there are significant differences in disease conditions. Bacterial diseases are moldless, while fungal diseases include molds (mycelium, spores, etc.). Bacterial diseases include:

(1) The site of the spotted and leaf-blight bacterial disease begins with a spotted, translucent, water-translucent lesion. When it is wet, there are a large number of stomata, pores, lenticels, and wounds on the leaf. The bacteria spilled out of the mucus--bacterial pus. Such as bacterial leaf blight of rice, bacterial blight of rice, bacterial leaf streak disease diagnosed, according to this judgment.

(2) Definitive diagnosis basis for the vegetative and leaf-blight bacterial diseases. Cut the diseased stem with a knife and observe whether the vascular bundle in the stem section has changed and squeeze it by hand. That is, a milky viscous liquid flows out of the catheter - bacteria. pus. The use of bacterial pus can be distinguished from fungal blight. Identification of bacterial wilt and blight of eggplant can be distinguished by this method.

(3) The common feature of rot-type bacterial diseases is that the diseased part has soft rot, sticky slip, no residual fiber, and odor of hydrogen sulfide. The rot caused by the fungus has fiber residues and no odor. Such as the identification of cabbage soft rot and sclerotinia commonly used this method.

(4) After the observation of the pathological condition and the initial diagnosis of the field distribution as a bacterial disease, it is necessary to further confirm the diagnosis. Select the standard disease samples in the field, rinsing in the room, wash away dirt and dirt, and then cut the typical part of the disease, rinse with distilled water (or cold water) a few times, and then make the specimen slice or squeeze out the disease sap On slides, the coverslip was microscopically examined and diagnosed according to the morphology.

The method is to cut a small piece of fresh disease tissue on a glass slide, place a small amount of water on it, cover it with a glass slide, and lightly press it. It can be seen that a large number of bacteria gushes out of the plant tissue and the cloud-like fungus spring springs out. Early detection of rice bacterial blight is often used this method.

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Sixth, commonly used agents for the control of bacterial diseases

The following will list some common bactericides that have a good effect against bacterial diseases. In fact, the bactericides introduced are often not only true to bacterial diseases, some formulations are equally effective against viral diseases and fungal diseases, but this article no longer distinguishes them.

1, organic copper fungicides

Common preparations include copper thiazolyl (Loncobacter), copper oxalate, copper rosinate (chloromycin, green copper, copper manufactory), copper succinate (DT), copper phthalocyanine (golden lake), quinoline Copper (Haizhen Thousand Bacteria, Must Green), Thousand Copper, etc. This kind of fungicide has good control effect on some bacterial diseases.

Advantages and Disadvantages: The advantages of this type of bactericide include: more safety, generally no phytotoxicity, flowering and young fruit can also be used; wide range of use and time, rice, vegetables, fruits, etc.; copper content is relatively low It will not cause the proliferation of crickets and the accumulation of copper will be small; it will have good compatibility, ease of use, and lightening of the burden. Disadvantages of organic copper preparations include: generally higher prices; the market is growing and is a latecomer to the market.

Due to space limitations, only the thiazole copper is briefly introduced. The structure of copper thiopia is composed of two groups. One is the thiazole group, which is a highly effective therapeutic agent in plants. In the pore conduits of the plants, the bacteria are severely damaged, and their cell walls become thinner and then collapse, leading to the death of the bacteria. The second is copper ion, which has the effect of killing bacteria and killing fungi. In short, under the joint action of the two groups, the sterilization is more thorough, the control effect is better, and the control objects are more extensive.

The toxicity of copper thiazolybdate is very low, and 20% of copper thiazolyl SC is mildly irritating to the skin and eyes; 20% of copper thiazolyl SC is a weak sensitizer to the skin. The disease is not easily resistant to thienoa copper. Thiobacillus contains copper ions in its structure, and the copper preparation is a product with a history of more than two hundred years. The development of drug resistance is very slow. Thiobacillus copper does not produce phytotoxicity and the residue is extremely low. Because the effective copper content of Thiobacillus copper is 3.9%, it does not cause any serious problems. At the same time, in actual use in Daejeon, the residual copper content does not exceed the allowable residue level. Efficacy of endurance test, 20% SC copper in the usual dosage, the effective period of up to 10-14 days.

There are many suitable crops of B. thibetana and a wide spectrum of control. Can be widely used in more than 20 kinds of crops more than 60 kinds of bacteria and fungal diseases prevention and treatment. Bacterial diseases include rice bacterial leaf blight, rice bacterial blight, rice-based rot, citrus canker, pomelo canker, cucumber bacterial leaf spot, cotton leaf spot, and garlic leaf blight. Melon angular spot, cabbage soft rot, peanut bacterial wilt, tobacco wildfire, tobacco bacterial wilt, konjac soft rot, ginger ginger pod disease, pepper bacterial wilt, bacterial disease of flower seedlings, peach bacterial puncture Wait.

2, inorganic copper fungicides

Common inorganic copper bactericides include: hydrogen puncture copper (can kill 101, kill 2000, crown bacterium clear, copper crown, Ruifu 2000, etc.), urinary copper (copper master, backing, etc.), Basic copper sulfate (Bordeaux, etc.), itch copper chloride (Wang copper, etc.). Inorganic copper bactericides have become traditional products accepted by farmers and merchants, and the market is mature.

The advantages of this type of bactericide include: it is a protective bactericidal agent with advantages; some of the lower price, the cost has a comparative advantage; no business propaganda and more money.

However, it should be noted that inorganic copper preparations also have their disadvantages: they are prone to phytotoxicity and are prohibited or restricted in use at the flowering and young fruit stages; they are poorly miscible, and most inorganic copper preparations are alkaline pesticides and cannot be mixed with most pesticides. It is inconvenient to use; induces the proliferation of ticks and rust ticks, increases the cost of disguised prevention and control; the market is chaotic, the profit margin is small, the competition of similar copper preparations is fierce; the effect of treatment is not strong; it is not easy to use on rice.

3, antibiotic pesticides (agricultural antibiotics)

Some antibiotics are bactericidal substances produced in the process of microbial metabolism, have the effect of inhibiting the growth and development of other species of microorganisms, as well as hindering their physiological functions, and have a good control effect against bacterial diseases. The use of the more common streptomycin, gold nucleus, oxytetracycline hydrochloride, cycloheximide, mesitectin, Kang Leilei, etc., are currently the main widely used antibiotic varieties.

The use of agricultural antibiotics should be based on different plant diseases to choose the appropriate method of drug use.

For soil-borne plant diseases, it can be used as a soil disinfectant; for seed and seedling-infected plant diseases, it can be impregnated with antibiotics, such as soaking, immersing roots, immersing seedlings, etc., or spraying on the seedbed; the above-ground diseases of agricultural and forestry crops The plant can be sprayed with the sun at the right time. When used on fruit trees, it is mainly used as an ointment to prevent bacterial ulcers.

In order to improve the antibiotic effect of antibiotics, some synergist and metal ions are often added when antibiotics are used. Adding synergists can promote the spread and absorption of antibiotics. Common synergists include glycerol and other polyhydroxy compounds. At present, 190 glycerol is added to agricultural antibiotic preparations that are generally used as commercial products. Hydroxyl compounds have a strong water absorption effect, which can prolong the effective absorption period of the antibiotics, promote the hydration of the stratum corneum on the leaf surface of plants, and enhance the water permeability of the leaf surface. The addition of metal ions can make the antibiotics complex, so that the efficacy is significantly improved. For example, the addition of 1% to 2% copper sulfate compound endotherapy can prolong the life of the drug in the plant and enhance the disease resistance of the plant.

The advantages of this type of fungicides include: high acceptance by the general public, relatively popular market, and some markets are deeply entrenched; they are traditional bactericides; they have a high dilution ratio and have a comparative advantage in price; they can also be purchased without advertising or promotion. No effort; inner suction and treatment are better. Disadvantages include: the dealer's profit margin is relatively small, the price is very transparent, the business is unprofitable; the product is very resistant to drugs, the control effect is poor; the harm of antibiotics to humans, animals and plants (the state will soon introduce the law "Antibiotics" As "prescription drugs" to prevent the abuse of antibiotics; more fakes, market chaos, price chaos. Agricultural antibiotics with good control effect against bacterial diseases such as:

Agricultural streptomycin is an efficient, low-toxicity, low-residue, pollution-free and environment-compatible antibiotic pesticide. It is used as both a therapeutic and protective agent. It is a systemic and environment-friendly fungicide. Streptomycin is a nuclear factor produced by Streptomyces griseus. The industrial product is the trihydrochloride of streptomycin which is a white amorphous powder. A city of honor is soluble in water and insoluble in most organic solvents. It has the advantages of wide antibacterial spectrum, strong selectivity, and easy absorption by crops, especially for bacterial diseases. Formulations include 72% soluble powders, effervescent tablets, and 20% soluble powders. Can be mixed with antibiotic pesticides to avoid mixing with alkaline pesticides and sewage, otherwise it is easy to fail. This medicine is widely used in diseases such as wildfire, bacterial wilt, angular spot, soft rot, ulcer disease, bacterial leaf blight, anthrax, and other diseases on tobacco, vegetables, fruit trees, and food crops. An ideal agent for sexual diseases. The use should be based on prevention, crops after the start of the drug, visible crop growth period and the severity of the adjustment of the amount of medication and the number of medication.

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VII. Bacterial Diseases in Agriculture and Physical Control

1. Agricultural control

(1) Use disease-free seed or resistant and disease-resistant varieties to retain seed from disease-free or disease-free plants.

(2) The intercropping intercropping of cruciferous vegetables should be carried out with leguminous vegetables, solanaceous vegetables and food crops, or with garlic.

(3) Implementing key cultivation to enhance the disease resistance of vegetables:

1 Reasonable fertilization. Apply sufficient farmyard manure and phosphorus and potassium fertilizers to cultivate strong seedlings and strong plants.

2 improve the soil, 1-2 times per minute application, can adjust the soil PH value, inhibit the propagation of bacteria, improve crop resistance to disease.

(4) Level land and refurbish irrigation and drainage systems. Prevent the accumulation of water in the field, adopt high ridge or sorghum cultivation methods, and timely watering the drought to prevent ripping of roots. After the rain, prepare for drainage and prevent the occurrence of bacterial soft rot.

(5) Strengthen field management:

1 timely control of pests. Reduce plant wounds. Chinese cabbage can control the occurrence of soft rot.

2 Protecting cultivation should avoid excessive humidity in the shed to prevent dripping and condensation.

3 Remove the diseased plant and remove the diseased fruit. When soft rot diseased plants first saw the field, they should be promptly removed and disinfected with lime.

2. Physical control

(1) Seed disinfection:

1 warm soup soaking. Seed soaked with cold water, and then placed in warm water immersed in 50 °C for 20 minutes, remove and re-germination after sowing with cold water.

2 high temperature dry heat disinfection. The dried seeds were sterilized by dry heat at 60°C for 6 hours.

3 biological, chemical agent soaking. Use 72% agricultural streptomycin sulfate wet acne 500 times liquid soak 2 hours, or 40% formalin 150 times soak 1.5 hours.

4 chemical seed dressing. With 50% ceric chloride copper wettable powder 0.4% seed size seed dressing.

(2) Solar energy soil disinfection: The use of solar energy to disinfect non-pollution, no pesticide residues, suitable for greenhouses.

Time: Generally selected during the high-temperature season in July-August, or in the idle period of open ground.

Method: The basal fertilizer was applied to the ground and ridged after ploughing. The ridge width was 60-70 cm and the height was about 30 cm. The ridge was covered with a polyethylene film with a thickness of 0.5 mm. The film was laid flat and tightened, and the soil was compacted around the soil. Drench the greenhouse greenhouse to close the doors and windows closed. The ground shall be covered with a layer of film and compacted with fine soil around it. During the disinfection period, the irrigation was performed 6-7 days according to the situation, and the soil moisture content was maintained at more than 60% of the maximum water holding capacity in the field, and was confined for 20-30 days. Using this method, the temperature of 0-20 cm soil layer in the soil can reach above 50°C, and the soil can be thoroughly disinfected.

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