Causes
The occurrence and prevalence of melon disease must have three conditions in greenhouses and greenhouses: melon plants susceptible to disease; a certain number of pathogens; environmental conditions suitable for the onset of temperature and humidity.
Pathogen. The presence of pathogens is a prerequisite for disease, and the pathogens mainly include fungi, bacteria and viruses. These germs have attached or parasites on certain objects and are transmitted to the plants through certain routes when the conditions are appropriate.
The route of transmission is: 1 seed carrier. Seed carriers are the main means of disease transmission. Such as melon bacterial leaf spot, anthracnose, vine and other pathogens can be overwinter or summer on the seeds; 2 seedbed with bacteria. Seedbed bacteria are the main route of transmission of seedlings. The seedbed is taken from the planting block of the melon crop or the organic fertilizer with the pathogen and not decomposed is used to cause the seedbed to carry the bacteria; In the seedlings and planting, the seedlings are not strictly selected and eliminated. If the diseased plants are not checked and removed in time after planting, the diseased seedlings will grow in the field and develop into a central disease plant; 4 diseased plants, weeds and Unfermented organic fertilizer with bacteria. After harvesting, the melons are not picked up in time. The remaining roots, alfalfa, leaves and fruits are not cleaned, buried or burned. A large number of pathogens remain in the field. Once the conditions are suitable, the plants will be infested; In the greenhouses and greenhouses that have been re-emerged for many years, the more the pathogens accumulate, the more serious the disease is. Therefore, soil-borne bacteria are also an important transmission route for melons; 6 irrigation water-borne bacteria. The pathogens contained in the water are usually washed out from the contaminated soil and pathogen residues. Irrigation water flows through the soil of the bacteria, or the residue of the diseased plant can spread the disease; 7 insects carry bacteria. Insects that are mainly sucking mouthparts, such as mites eating plants with viral diseases, then sucking healthy plants and spreading the virus at the same time; 8 airborne bacteria. In the onset of melon, the air contains a large number of pathogenic bacteria, once the conditions are appropriate, it is infected and infected; 9 Others. Greenhouses, greenhouse facilities, racks, agricultural tools, human bodies, etc. can also carry bacteria and spread diseases.
Suitable environmental conditions. Appropriate temperature and humidity are the main conditions for the onset, especially humidity. Higher humidity is required for the germination of most fungal spores and the development of hyphae. For example, blight, black spot, and gray mold, the relative humidity of the air needs to be above 90%, and the bacterial angular spot disease requiring low humidity is more than 70%.
Causes of suitable humidity: 1 continuous rain. Insufficient sunshine in the rainy days, low temperature in the shed, poor ventilation, and high outdoor humidity, so the humidity in the shed is very high, which creates conditions for the occurrence and prevalence of diseases. 2 less wind. In greenhouses and greenhouses, in order to keep warm during the cold season, the air release time is short and small, so the humidity in the greenhouse is increased. 3 insufficient bottom water or less tillage, resulting in more irrigation times and greater humidity in the field. Before planting or after planting, the bottom water is not poured; in addition, the floor panel will cause evaporation and the soil will lose water quickly, which will increase the number of watering and accelerate the occurrence and prevalence of the disease. 4 planting density is too large. The plants are not too dense and cause poor ventilation, which makes the humidity in the shed too large. 5 The quality of the land preparation is not high. The soil is not flat, the surface is too large, the watering is uneven, and the low water is easy to accumulate water, which is easy to become the center of the disease. 6 shed film dripping. When the temperature difference between the inside and outside of the greenhouse is large, water droplets and water film are easily formed on the inner side of the greenhouse film. The soil with a lot of dripping water has a large humidity and is prone to disease.
Prevention
Reduce pathogens. 1 reduce seedbed pathogens. Avoid using the soil of the old seedbed, and use the soil of the fertile land that has not been planted for more than 3 years to make the seedbed soil. The bed land is disinfected and the fertilizer applied to the seedbed is fully decomposed. 2 to prevent seed poisoning. Strengthen quarantine, try to transport seeds in the disease-free area. If the seeds are transported in the ward, the seeds should be disinfected. The methods include warm soaking, chemical dressing, and dry heat treatment. 3 Prevent the sick seedlings from entering the field. Before planting, careful inspection should be carried out to eliminate sick and weak seedlings. Spraying a broad-spectrum fungicide in the seedbed for prevention. 4 Implement rotation and pay attention to intercropping. The melons that planted melons try not to plant other melon crops. 5 soil disinfection. Deeply turn 30 cm and make a ridge. When the greenhouse is closed in the summer, the temperature in the shed is raised, so that the surface temperature reaches 50 °C - 60 °C, and the treatment is for 10-15 days, and 50% of carbendazim 500 times solution is sprayed before planting. 6 shed room disinfection. 10-15 days before sowing or planting, 1 to 1.5 kg of sulfur powder per acre chamber, 3 kg of sawdust, 5 to 6 places on iron pieces, or 4 g of 45% chlorothalonil. Close the shed. 7 clean the countryside. During the growth of melon, the weeds are removed in time, the leaves and fruits of the disease are removed, and the diseased plants are removed, and the fields are buried or burned. After the melon is pulled, the debris is cleaned up or burned in time.
Reduce humidity. Before sowing, the planting water should be poured after the planting, and the seedlings should be poured after the seedlings are slowed down. If you need to water the growth period, you should ditch the small water to cover the no-drop film; the ridges cover the mulch; the reasonable dense planting, use the large-scale cultivation to facilitate ventilation; the cold season watering should be carried out in the sunny morning.
Adjust the temperature. The onset temperature of melon downy mildew is 22 °C - 22 °C, avoiding this disease during cultivation can avoid the occurrence of disease. To this end, greenhouses and temperatures can be kept at a low temperature of 15 ° C - 18 ° C during the night, and the temperature in the greenhouse and greenhouse can be rapidly increased to 25 ° C - 28 ° C in the morning.
Cut off the source of infection. When working in the field, try to avoid the cross-contact of sick and healthy plants, pay attention to timely control of aphids, and take the sickness out of the field.
Agricultural control. 1 Select resistant varieties. Such as Elizabeth, Taiwan Cuixiang and so on. 2 Strengthen field management. To increase the application of organic fertilizer, it is necessary to maintain sufficient light, suitable temperature and humidity, and pruning in time. 3 grafting. The use of black seed squash for grafting can be used to control blight. 4 external top dressing. The application of nutrient elements outside the roots, such as the use of sugar and urea mixture (sugar 0.75 kg, urea 0.75 kg, water 50 kg) spray once every 5-7 days, can reduce the occurrence of downy mildew. Top dressing. 0.2% potassium dihydrogen phosphate also has the effect of preventing disease.
Chemical control. In the early stage of the disease, the central disease plant should be prevented in time to control the occurrence of the disease. The pesticides used are best biological pesticides, followed by low-toxicity and low-residue pesticides. For the prevention and treatment of bacterial diseases, 72% of agricultural streptomycin sulfate 4000 times solution and 14% copper complex water solution 200 times solution should be used. Control leaf foliar disease can be used for 45% chlorothalonil smoke, or 10% keeling smoked smoke, 250 grams per mu of greenhouse, sprayable pesticides with 75% chlorothalonil or 70% mancozeb Zinc, 500-600 times liquid, 40% ethyl phosphorus aluminum 200 times liquid, 200% liquid 2% agricultural resistance 120, Xiaosu want 500 times liquid. In the early stage of the disease, the virus A 500 times liquid or 1.5% phytopathogenic water emulsion 800-1000 times liquid, 0.5% mushroom protein multi-tang water 300 times liquid, can also use silver gray plastic film or black plastic film to avoid cockroaches Prevent disease.
Author: Jiaorui Lian
Source: Shaanxi Science and Technology News
The occurrence and prevalence of melon disease must have three conditions in greenhouses and greenhouses: melon plants susceptible to disease; a certain number of pathogens; environmental conditions suitable for the onset of temperature and humidity.
Pathogen. The presence of pathogens is a prerequisite for disease, and the pathogens mainly include fungi, bacteria and viruses. These germs have attached or parasites on certain objects and are transmitted to the plants through certain routes when the conditions are appropriate.
The route of transmission is: 1 seed carrier. Seed carriers are the main means of disease transmission. Such as melon bacterial leaf spot, anthracnose, vine and other pathogens can be overwinter or summer on the seeds; 2 seedbed with bacteria. Seedbed bacteria are the main route of transmission of seedlings. The seedbed is taken from the planting block of the melon crop or the organic fertilizer with the pathogen and not decomposed is used to cause the seedbed to carry the bacteria; In the seedlings and planting, the seedlings are not strictly selected and eliminated. If the diseased plants are not checked and removed in time after planting, the diseased seedlings will grow in the field and develop into a central disease plant; 4 diseased plants, weeds and Unfermented organic fertilizer with bacteria. After harvesting, the melons are not picked up in time. The remaining roots, alfalfa, leaves and fruits are not cleaned, buried or burned. A large number of pathogens remain in the field. Once the conditions are suitable, the plants will be infested; In the greenhouses and greenhouses that have been re-emerged for many years, the more the pathogens accumulate, the more serious the disease is. Therefore, soil-borne bacteria are also an important transmission route for melons; 6 irrigation water-borne bacteria. The pathogens contained in the water are usually washed out from the contaminated soil and pathogen residues. Irrigation water flows through the soil of the bacteria, or the residue of the diseased plant can spread the disease; 7 insects carry bacteria. Insects that are mainly sucking mouthparts, such as mites eating plants with viral diseases, then sucking healthy plants and spreading the virus at the same time; 8 airborne bacteria. In the onset of melon, the air contains a large number of pathogenic bacteria, once the conditions are appropriate, it is infected and infected; 9 Others. Greenhouses, greenhouse facilities, racks, agricultural tools, human bodies, etc. can also carry bacteria and spread diseases.
Suitable environmental conditions. Appropriate temperature and humidity are the main conditions for the onset, especially humidity. Higher humidity is required for the germination of most fungal spores and the development of hyphae. For example, blight, black spot, and gray mold, the relative humidity of the air needs to be above 90%, and the bacterial angular spot disease requiring low humidity is more than 70%.
Causes of suitable humidity: 1 continuous rain. Insufficient sunshine in the rainy days, low temperature in the shed, poor ventilation, and high outdoor humidity, so the humidity in the shed is very high, which creates conditions for the occurrence and prevalence of diseases. 2 less wind. In greenhouses and greenhouses, in order to keep warm during the cold season, the air release time is short and small, so the humidity in the greenhouse is increased. 3 insufficient bottom water or less tillage, resulting in more irrigation times and greater humidity in the field. Before planting or after planting, the bottom water is not poured; in addition, the floor panel will cause evaporation and the soil will lose water quickly, which will increase the number of watering and accelerate the occurrence and prevalence of the disease. 4 planting density is too large. The plants are not too dense and cause poor ventilation, which makes the humidity in the shed too large. 5 The quality of the land preparation is not high. The soil is not flat, the surface is too large, the watering is uneven, and the low water is easy to accumulate water, which is easy to become the center of the disease. 6 shed film dripping. When the temperature difference between the inside and outside of the greenhouse is large, water droplets and water film are easily formed on the inner side of the greenhouse film. The soil with a lot of dripping water has a large humidity and is prone to disease.
Prevention
Reduce pathogens. 1 reduce seedbed pathogens. Avoid using the soil of the old seedbed, and use the soil of the fertile land that has not been planted for more than 3 years to make the seedbed soil. The bed land is disinfected and the fertilizer applied to the seedbed is fully decomposed. 2 to prevent seed poisoning. Strengthen quarantine, try to transport seeds in the disease-free area. If the seeds are transported in the ward, the seeds should be disinfected. The methods include warm soaking, chemical dressing, and dry heat treatment. 3 Prevent the sick seedlings from entering the field. Before planting, careful inspection should be carried out to eliminate sick and weak seedlings. Spraying a broad-spectrum fungicide in the seedbed for prevention. 4 Implement rotation and pay attention to intercropping. The melons that planted melons try not to plant other melon crops. 5 soil disinfection. Deeply turn 30 cm and make a ridge. When the greenhouse is closed in the summer, the temperature in the shed is raised, so that the surface temperature reaches 50 °C - 60 °C, and the treatment is for 10-15 days, and 50% of carbendazim 500 times solution is sprayed before planting. 6 shed room disinfection. 10-15 days before sowing or planting, 1 to 1.5 kg of sulfur powder per acre chamber, 3 kg of sawdust, 5 to 6 places on iron pieces, or 4 g of 45% chlorothalonil. Close the shed. 7 clean the countryside. During the growth of melon, the weeds are removed in time, the leaves and fruits of the disease are removed, and the diseased plants are removed, and the fields are buried or burned. After the melon is pulled, the debris is cleaned up or burned in time.
Reduce humidity. Before sowing, the planting water should be poured after the planting, and the seedlings should be poured after the seedlings are slowed down. If you need to water the growth period, you should ditch the small water to cover the no-drop film; the ridges cover the mulch; the reasonable dense planting, use the large-scale cultivation to facilitate ventilation; the cold season watering should be carried out in the sunny morning.
Adjust the temperature. The onset temperature of melon downy mildew is 22 °C - 22 °C, avoiding this disease during cultivation can avoid the occurrence of disease. To this end, greenhouses and temperatures can be kept at a low temperature of 15 ° C - 18 ° C during the night, and the temperature in the greenhouse and greenhouse can be rapidly increased to 25 ° C - 28 ° C in the morning.
Cut off the source of infection. When working in the field, try to avoid the cross-contact of sick and healthy plants, pay attention to timely control of aphids, and take the sickness out of the field.
Agricultural control. 1 Select resistant varieties. Such as Elizabeth, Taiwan Cuixiang and so on. 2 Strengthen field management. To increase the application of organic fertilizer, it is necessary to maintain sufficient light, suitable temperature and humidity, and pruning in time. 3 grafting. The use of black seed squash for grafting can be used to control blight. 4 external top dressing. The application of nutrient elements outside the roots, such as the use of sugar and urea mixture (sugar 0.75 kg, urea 0.75 kg, water 50 kg) spray once every 5-7 days, can reduce the occurrence of downy mildew. Top dressing. 0.2% potassium dihydrogen phosphate also has the effect of preventing disease.
Chemical control. In the early stage of the disease, the central disease plant should be prevented in time to control the occurrence of the disease. The pesticides used are best biological pesticides, followed by low-toxicity and low-residue pesticides. For the prevention and treatment of bacterial diseases, 72% of agricultural streptomycin sulfate 4000 times solution and 14% copper complex water solution 200 times solution should be used. Control leaf foliar disease can be used for 45% chlorothalonil smoke, or 10% keeling smoked smoke, 250 grams per mu of greenhouse, sprayable pesticides with 75% chlorothalonil or 70% mancozeb Zinc, 500-600 times liquid, 40% ethyl phosphorus aluminum 200 times liquid, 200% liquid 2% agricultural resistance 120, Xiaosu want 500 times liquid. In the early stage of the disease, the virus A 500 times liquid or 1.5% phytopathogenic water emulsion 800-1000 times liquid, 0.5% mushroom protein multi-tang water 300 times liquid, can also use silver gray plastic film or black plastic film to avoid cockroaches Prevent disease.
Author: Jiaorui Lian
Source: Shaanxi Science and Technology News
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