The pear tree is native to China and is one of the major fruit trees in China. The cultivated area ranks third in terms of the area of ​​apple and citrus, the output is second only to apple production, and ranks first in the world. Pear fruit is rich in nutrients, crisp and juicy flesh, sweet and refreshing, with the effect of helping digestion, lungs and pure heart, expectorant and cough, and antipyretic fever. Pear fruit has a long period of supply. Many varieties are more resistant to storage and transportation, which is of great significance in regulating the fruit market and ensuring the supply of fruits. However, it is also very prone to cause diseases during storage, with the exception of latently infected ring vein disease and brown rot. Diseases such as diseases continue to be cleaned up during the storage period and should be cleared in time. Other major diseases include black heart disease, pedicel base rot, penicillium, melanosis, mold heart disease, cold injury, and carbon dioxide poisoning. During storage, timely and effective prevention and treatment of these diseases can have a multiplier effect. 1. Black heart disease (1) Symptoms of early onset of storage, first in the heart of the heart of the ventricular wall and the vascular junction of the stem, the formation of sesame seed size light brown lesions, and then extended to the ventricle, so that the whole fruit into black Brown, flesh tissue hair, bad taste. In general, the appearance of the fruit does not change significantly. If the fruit surface is squeezed by hand, there will be a mild soft cotton sensation. In severe cases, the skin color will be dark and inedible. (2) Onset of disease Due to calcium deficiency, enzymatic browning of polyphenolic compounds in fruits results in the formation of black hearts and brown meat. Pear black heart disease begins with browning from carpels or vascular bundles near the ventricular tachycardia and gradually spreads throughout the heart of the fruit. Mildly affected ventricle remains white, and the severely affected pear fruit completely darkens. Pleurotus eryngii lesions started from the flesh tissue, and the pulp tissue became red-brown, and the fruit hardness was significantly reduced. In severe cases, the entire pulp tissue became brown or lightly corked. (3) Prevention and control approach 1 Storage in the shortest time possible; 2 Pay attention to slow cooling after storage, and reduce the temperature of the reservoir to 0°C-4°C within 15 days-20 days. 2. Fruit basal rot (1) Symptoms from the base of the stalk start rot. There are 3 types: 1 Water erosive type, which begins to produce light brown, water-stained spots on the base of the stalk. Rot; 2 brown rot type, starting from the base of the stem to produce brown ulceration lesions, to the fruit surface expansion rot, rotten fruit slower than the water rotten type; 3 black rot, the base of the fruit stem began to produce black rot lesions, to Fruit surface expansion, rotten fruit slower than brown rot. (2) Incidence of disease The base rot of pear pedicel is mainly caused by complex infections of Alternaria, Auricularia, Scabella and other fungi. Subsequent infections such as Rhizopus and other rot-producing molds further saprophyte and promote fruit rot. . Shaking the fruit handle to cause internal injuries when harvesting is the main cause of the disease. Dehydration of stems often aggravates the disease. (3) Prevention and cure method 1 Try not to shake the fruit handle to prevent internal injuries when harvesting; 2 Use 50% of carbendazim to wash the fruit after 1000 days to reduce the occurrence of diseases; 3 Keep the humidity at 90% during storage— 95% can effectively prevent dried fruit stems. 3. Penicillium (1) Symptoms at the onset of the onset of symptoms in the wounds of the fruit surface produced pale yellow-brown small lesions. In the late onset, the diseased tissue was water-stained and spread to the ventricle with a pungent odor. When the temperature is right, the pear fruit will soon be muddy and the disease minister will have a greenish moldy texture. (2) Incidence of disease Penicillium piriosa is caused by Penicillium. Its germs are widespread in nature and invaded by pear fruit. Storage temperature is high and the incidence is heavier. (3) Prevention and control methods 1 Remove wounds and wounds, prevent wounds, to reduce the invasion of pathogens; 2 Before storage of the fruit should be disinfected and sterilized, generally sulfur powder can be mixed with appropriate amount of sawdust burning fumigation method to control each 100 cubic meters of volume, available sulphur powder 2kg - 2.5kg, closed 48h after ignition, and then ventilation can be. 4. Dark skin disease (1) Symptoms During the storage of pome fruits, irregular black-brown patches are formed on the surface of the peel, and the heavy ones are even joined into large pieces, even spreading to the entire fruit surface, affecting the appearance and the value of the product. The performance of subcutaneous pulp was normal and did not affect the consumption. (2) Incidence of disease In the early stage of storage, a large amount of farnesene is produced in the epidermis of pear fruit. By the mid and late stages, the farnesene is oxidized to conjugated triene, which injure the cortical cells, resulting in the occurrence of black dermatosis. If there are many such substances, post-harvest pome fruit will not be able to be pre-cooled in time, so black skin disease will easily occur. (3) Prevention and cure method 1 Wrap the pear fruit with the wrapper wrapped with the negative 3rd power of Tiger Pi Ling medicinal liquid with a mass fraction of 110, which can significantly reduce the occurrence of diseases; 2 timely storage and pre-cooling to prevent pome fruit from being piled on The park was blown by the wind, the sun, and the rain. 5. Pear Mold Heart Disease (1) Symptoms A brown, dark brown spot develops on the wall of the pear's heart, and then the heart turns dark brown, and the disease minister produces gray or white hyphae. Ventricular pathogens continue to spread outwards, and the fruit rots outward from the inside, and when it reaches the fruit surface, it becomes a damp, rotten fruit. (2) Incidence of the disease Pear mold heart disease is the result of complex infestation by a variety of weak parasitic fungi. Among them, common pathogens include Alternaria, Fusarium, and Trichothecenes. These pathogens are common in pear orchards, and they invade from the stigma and saplings during the flowering and growing stages. (3) The prevention and control methods are discovered in time, collected in time, and disposed in a timely manner. 6. Cold damage (1) Symptoms The flesh tissue is dehydrated and necrotic, and it is stained with water stains. At the same time it induces the activity of Penicillium, Alternaria, and rotten bacteria on the surface of the peel and waxy layer to speed up the fruit rot. . (2) Incidence and regularity Pears were rapidly cooled in storage and entered the storage room around 0°C from a temperature of 20°C. It is easy to cause black heart disease. Pear fruit can withstand 0 °C low temperature during storage, if the temperature is lower than -5 °C, pear fruit water will gradually freeze. When icing, the first is the condensation of water in the intercellular space. When the temperature continues to fall, the ice crystals will gradually increase and absorb water from the cells. The concentration of the cell fluid will become higher and higher until the irreversible coagulation of the protoplasm occurs and the pulp will be necrotic. ,corruption. (3) Control method The freezing point temperature of pear fruit is -1.8°C-3°C. If it is lower than the freezing point temperature, pear fruit will be chilled. The general storage and preservation temperature is not lower than 0°C, but it cannot be higher than 5°C. If it exceeds 5°C for a long time, it will accelerate the aging of pear fruit and increase the decay rate. 7. Carbon dioxide poisoning (1) Symptoms The pear heart's ventricle becomes brown and dark and forms watery lesions, which cause ulceration of the heart wall, which in turn causes pulp rot. Some pulps have a honeycomb brown lesion, tissue necrosis, lighter fruit weight, and bouncing sounds. (2) Incidence of disease Pear fruit has more water content after harvest, and its internal physiological activity is very strong and sensitive to carbon dioxide. If the carbon dioxide volume fraction during storage is too high, a large amount of ethanol, succinic acid, acetaldehyde and other substances will be produced in the pear fruit tissue, which will cause the whole pear fruit to rot. (3) Control measures Control the volume fraction of carbon dioxide in the storage environment. It is appropriate to use oxygen gas fraction of 12%-13% and carbon dioxide gas fraction of 1% or less.
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