The causes of post-harvest diseases in “fruit and vegetables†are complex. The pre-harvest sickness, post-harvest mechanical damage, temperature and humidity conditions, and physiological disorders caused by improper management are all contributing factors. Disease control measures are closely related to these factors. According to the survey, most post-harvest diseases and field diseases are the same pathogen. If rot, gray mold, soft rot, epidemic and bovine diseases, cotton rot, anthracnose, etc., the “fruits and vegetables†harvested on the plots where these diseases occur are often accompanied by a large number of pathogenic bacteria, although diseases are not seen at the time of harvest. , but it is very likely that the germs have invaded and are temporarily in a latent state, and after this fruit is harvested, there is a large number of diseases. Some pathogens, such as Rhizopus, do not cause diseases in the field and only cause rot after harvesting, but this pathogen can also multiply in the field. According to the test, the fungicide is sprayed 5 to 6 weeks before the harvesting of the tomatoes, then sprayed the second time 18 to 20 days before the harvesting, or sprayed once every 2 weeks before the harvesting. Continuous treatment 3 times can prevent the field The fungus reproduces on dead or aging leaves and can effectively control the occurrence of rot in tomatoes. Spraying appropriate bactericides before harvesting can also effectively reduce decay caused by post-harvest root mold. Therefore, the prevention of pre-harvest disease is closely related to the occurrence of post-harvest diseases. Even if the disease is not caused in the field and only after the harvest, the measures to reduce the density of field pathogens before harvest are also effective. Pre-harvest disease prevention shall adopt various comprehensive cultivation measures to guarantee the healthy growth of “fruits and vegetablesâ€, including selection of resistant and resistant varieties, cultivation of field crops, good management of field hygiene, selection of appropriate chemical control (safety interval is 7 to 14 days), etc. . When harvesting, healthy plots should be selected for harvesting, and no disease-free and undamaged fruits can be selected from diseased plots. This cannot be ignored. Some pathogens in post-harvest diseases of "fruit and vegetable" are highly parasitic, such as Phytophthora, anthrax, etc., which can directly invade from the epidermis of fruit and cause disease. However, more germs are weakly parasitic or saprophytic. They need to take place from the time the wound penetrates or the product is subjected to physiological injury (such as cold damage). For example, gray mold and rhizopus are invaded by wounds or soft petals. Because the petal opened by the green pepper is easy to fall off, the flower end is less susceptible to disease, and most of the rot is caused by invasion of the pathogen from the incision of the handle. The petals of cucumbers often adhere to melons, so the gray mold of cucumbers occurs at the flower ends. For these diseases, the following measures have certain control effects. 1. Minimize mechanical damage. 2. Use sharp scissors to cut the stalk to a smooth incision, making the incision form the callus as soon as possible; 3. Remove the withered petals. In the process of harvesting and transportation, attention should also be paid to the cleanliness of the used packaged goods. The vegetable baskets used for food should be disinfected before use. Because the vegetable baskets are used to hold the dishes for many years, they will inevitably contain rotting bacteria, if not sterilized. It will infect the healthy fruit in the process of harvesting, causing the disease. The proper temperature should be strictly controlled during storage. Most post-harvest diseases develop rapidly at higher temperatures, and proper low temperatures can control their development, but fruits and vegetables should not cause cold damage due to low temperature. Fruit rot, gray mold, etc. often occur in large quantities in the case of cold damage to the fruit. Therefore, proper storage temperature should be strictly controlled to reduce decay loss. In order to prevent moisture loss, “fruits and vegetables†are often packaged in plastic film, so they are often in a high-humidity state. Treating with appropriate chemical agents can significantly reduce decay. Such as BF anti-mildew fumigation agent (including 50% sec-butylamine), SB (secondary butylamine derivatives), CHC (calcium hypochlorite preparations) for fruit and vegetables have a better effect. However, most of these agents have a good inhibitory effect on pathogens such as anthrax, gray mold, and fruit rot that adhere to the surfaces of fruits and vegetables, but pathogens such as soft rot and epidemics have invaded fruit and vegetables before use. The effect is not ideal. Storage should always check the storage situation and find the diseased fruit timely. However, when picking out, it is important to note that diseased fruit and fruit should be avoided. That is, the sap of the diseased fruit should not be dripped on the fruit. If you pick up the diseased fruit, you must first wash your hands and disinfect the fruit, and then contact the fruit. Or use a convenient bag wrapped in bad fruit, otherwise it will cause good fruit rot. During the storage and selection process, no attention is paid to the isolation of diseased and healthy fruit, which is the root cause of the more and more bad fruits in the storage. Including cabbage, potatoes, radishes, carrots and other storage, there are more and more bad phenomenon, the reason is also here. In short, the prevention and treatment of post-harvest diseases should start with pre-harvest prevention and control. From the plants that grow robustly and have almost no pests and diseases, they should be harvested, transported and transported with healthy fruits. Mechanical damage and various physiological injuries should be avoided to ensure that they are stored and stored. No sick, less bacteria. After entering the storage, appropriate temperature and humidity conditions should be controlled, and appropriate fresh-keeping packaging should be used, such as a TY storage bag with suitable air permeability and moisture permeability. Appropriate preservative treatment is also an effective aid.
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