More than 20 kinds of diseases can occur during the storage of citrus fruits after harvesting. Penicillium, green mold, black rot, coke rot and anthracnose are the infectious diseases. Physiological diseases include edema and brown spots. Illness and so on. 1, green and green mildew. The conditions of the two diseases are basically the same. In the early stage, it was a water-stained hazel-like round lesion. The diseased tissue was moist and soft, and the skin of the diseased part was easily broken with the fingers. The diseased department first grows white mycelium and quickly turns into a blue or green mold layer. Afterwards, the disease department continues to expand, causing the whole fruit to rot. The symptoms of the two diseases are slightly different. Penicillium: blue, white mold layer with a very narrow, slow decay, rotten fruit does not stick fruit paper, moldy smell. Green mold: blue-green, white mold layer is wider, decay faster, tightly sticky fruit paper, aromatic odor. 2, black rot. The fruit began to develop from the fruit pedicle. The first time there was a water-stained hazel-like lesion. After the enlargement, it was slightly depressed, dark brown, and the lesion had irregular edges. When the weather was wet, the disease minister was initially white and later became a dark green moldy layer. The rotted fruit also had a dark green mold layer. Some fruits do not show symptoms, but fruit and flesh have decayed. Rotten fruit also has a dark green mold layer. 3, coke rot, also known as black pedicel. Occurs before storage of the fruit after harvest. At the beginning of the disease, the skin surrounding the fruit pedicle appeared water-stained and brownish soft rot. After the disease, the lesion quickly spread outwards and the edge was wavy. The skin of the diseased part was dark purple-brown and extremely soft, and the peel was easily crushed. The root of the diseased department rots from the fruit pedicle to the umbilicus, causing "wounding through the heart," and the disease is black and bitter. 4, brown rot. The occurrence of sweet orange fruit was more, and at the early stage of disease, pale brown spots appeared on the peel, which spread rapidly and caused the whole fruit to decay within a few days. Under high-humidity conditions, the disease minister sparsely formed a layer of white mold with an aromatic odor. 5, edema disease. This disease is a kind of physiological disease, which occurs in the storage period of sweet orange and other fruits. Its characteristics are that the whole skin and pulp tissue are light brown water stains like edema, and then turn to dark brown, the pulp produces alcohol smell, completely lost Product value. The symptoms do not show symptoms of soft rot. 6, brown spot. The initial disease only showed brown leathery lesions on the hull layer of the skin, and finally reached the flesh, causing the odor of the pulp to spoil. Brown, irregular brown spots appear on the skin such as nets, flakes, and spots. The disease is a common physiological disease of orange fruit in the late storage period. In addition, brown pedicel and anthrax should also pay attention to prevention and treatment. How should we control it? Most of the pathogenic bacteria that cause diseases in the storage period of oranges are fungi with weaker parasitic characteristics. These pathogens invade the fruits and generally have to pass through various wounds on the peel. Therefore, they are collected, transported, and stored. In the middle, if the measures are improper, injuring the fruit will increase the incidence of the disease. Therefore, in order to reduce the occurrence of diseases during storage, the following prevention and control measures must be taken: (1) To prevent fruit injuries? To prevent fruit from mechanical damage during harvesting, storage and transportation. Timely harvesting of fruits and appropriate early harvest can prevent the occurrence of various storage diseases. Do not pick fruit when it rains, after rain, heavy fog or when dew is dry. (2) The fruit of the crown was sprayed about 10 days before the harvest to reduce the disease. Can spray 70% thiophanate-methyl wettable powder 1200-1500 times or 50% carbendazim wettable powder 1000 times. (3) Impregnation of fruit by medicine The current best medicine for dipping fruits is imazalil, which can overcome the penicillium and green molds that produce resistance to carbendazim and benzoate. Treating fruits with 75% imazalil 700 times and 0.02% 2,4-d can not only prevent fruit rot caused by green mold, but also have good control effect on black rot, peduncle and acid rot. . Or with 30% Tektronix 300 times plus 75% imazalil 700 times plus 0.02% 2,4-d dipping fruit, in addition to the above diseases have better control effect, but also have good prevention and treatment of anthrax The effect will be better if the fruit is processed immediately after harvest. (4)Single fruit packaging and storage? Single fruit packaging is more effective than large ones, and plastic film single fruit packaging is better than paper single fruit packaging. Agricultural polyvinyl chloride film is better than polyethylene film packaging. (5) Storage sterilize Before storage of the fruits, the warehouse shall be fumigated with 5-10 g of sulfur powder per cubic meter or 1:40 times of formalin, 30-50 ml/m3, closed fumigation 3 -4 days, before the medicine gas can be stored in storage. (6) Control the warehouse temperature and humidity Orange generally requires 3-4 °C and relative humidity of 80-85%. And pay attention to proper ventilation. China Agricultural Network Editor