Pay attention to two diseases of apple during storage
As China's apple production is increasing year by year, and the proportion of fresh sales and processing is small, most fruits need to be stored after apple fruit is picked. During fruit storage, if management and preventive measures are not in place, it will lead to some diseases, resulting in fruit rot and economic loss. The major diseases occurring during storage of apple fruits and their control methods are described below for reference. YT-T15 YT-T15 Shenzhen Sunshine Technology Co.,Ltd , https://www.yatwinsz.com
I. Apple tiger skin disease
1. Symptoms. Apple tiger skin disease, also known as brown scald, halo, is a kind of physiological disease in the late storage of apple, the symptoms are mainly manifested in the fruit. The main feature is that the skin is now halo irregular browning. In the early stage of disease, irregular pale yellow-brown patches appear on the fruit surface, and the surface is flat or slightly undulating around the fruit point. At this time, browning is limited to the subepidermis cells near the epidermis, and the browning endangers the pulp cells. The color of the diseased part changes. It is brown to dark brown, and the diseased skin is slightly sunken. Severe diseased skin can be peeled off into pieces. The flesh is soft, slightly chewy and easy to be infected by fungi. After the pit is removed, the diseased fruit is likely to spoil. At the beginning of the disease, some of them became brownish, slightly sunken, and had tiny protrusions. The diseased fruit was dried and contracted. It was firm and the skin peeled off. The diseased part first occurred in the uncolored part of the fruit's dark side. In severe cases, the large part of the stained part that ran into a large piece appeared to be burned, affecting the appearance.
2. Causes. The cause of the disease has not yet been finalized. Studies have shown that water-soluble phenolic substances and polyphenol oxidase (PPO) in fruits are prerequisites for the occurrence of tiger skin disease; also, it is believed that the occurrence of tiger skin disease is an excessively high cellar temperature during storage, poor ventilation, and volatile substances— - excessive accumulation of esters, absorption of esters by the fruit to cause metabolic disorders or "self-toxicity" effects; also believe that partial application of nitrogen fertilizer, especially in the early and mid-term application of excessive nitrogen fertilizer causes the fruit to harvest early or insufficient maturity led to the tiger Dermatosis occurs. In recent years, it has also been shown that α-famesene oxides, ie, conjugated trienes, are pathogenic substances of tiger skin disease.
3. Transmission routes and conditions. The occurrence of tiger skin disease is related to variety, cultivation techniques and storage environment. Late maturing varieties such as Hongyu, Xu, Marshal, Red Star and other basic diseases, green bananas, India, immature Fuji, Golden Crown disease is more serious, the country's lightest incidence. The same species in different years or different climatic conditions, the incidence rate is also different. The occurrence of this disease is related to the content of calcium in the peel, and the highest incidence of calcium in the peel is high, which is exactly the opposite of bitter pit disease. Partial application of nitrogen fertilizer, rainy years or too heavy watering disease. Early harvesting, low fruit maturity, insufficient surface wax and cuticle formation, rapid evaporation of water, wilting, and severe disease. If the storage period is too high or the ventilation is poor, the disease will be heavy. Especially during the March-April period after the spring, the temperature will rise and it will be easy to develop.
4. Control methods.
1 Strengthen cultivation and management, apply no nitrogen fertilizer and increase organic fertilizer.
2 timely harvest. For countries susceptible to disease such as Guoguang, India, and green bananas, etc., harvesting should be carried out after the fruit is mature, avoiding premature harvesting; Red Star apple should be harvested 140 days after flowering.
3 Pre-cooling before storage to control storage conditions. After pre-cooling, the apple is harvested so that it can be stored and transported as quickly as possible, and the fruit should be reduced to 0°C after storage. During the later period of storage, it is necessary to prevent the temperature of the cellar from being too high, maintain good ventilation, avoid sudden temperature rise when venting or use activated carbon and other adsorbents in the cellar to suppress the occurrence of diseases. If the use of controlled atmosphere storage, an appropriate increase in carbon dioxide concentration to 20% can reduce the incidence. Conditional use of "biphasic variable atmosphere storage" technology. For example, in the cave dwellings, apples are stored in plastic film. The initial kiln temperature is 10°C-15°C, the carbon dioxide concentration is 12%, the post kiln temperature is reduced to 0°C, and the carbon dioxide and oxygen concentrations are maintained at about 3%. Apples stored in this way are more effective than ordinary cold storage, and they can make full use of cave dwellings and cellars to make full use of simple facilities.
4 storage processing. Fruits are treated with antioxidants such as diphenylamine, tiger skin, etc. before storage.
5 drug dip fruit. The effective critical period for preventing and treating tiger skin disease is 6-8 weeks after harvesting, ie, the early storage period, with 0.25%-0.35% ethoxyquin solution or 1.5%-2.0% diphenylamine solution, and 1%-2% lecithin. The solution or 2-4 g / kg of 50% tiger skin cream soaked apples, dried in the air after packing, the residual amount of the drug on the fruit should not exceed 4-5 mg / kg. After coating the paper with the above agents, or after soaking the fruit box to dry it and packing it, all have better control effect.
Second, apple penicillium
Apple Penicillium, commonly known as "water rot" and "mild rot," is an invasive disease that is common during storage and can cause large losses to apples.
1. Symptoms. The fruit was killed and the surface of the lesion was yellow-white, concave, round, and extremely moist. When the conditions are right, it will develop rapidly and the whole fruit will rot for more than 10 days after onset.
2. Transmission routes and conditions. The pathogens are invaded by wounds caused by mechanical operations and insects. Although the lenticels can invade, they are secondary. When sick and healthy fruit are mixed together, they can be contacted and spread. When the air is wet, small mold-like mold pieces are produced, which are initially white and then turn blue-green, covered with powdered material, which is the conidia of pathogens. Penicillium fungus is resistant to hypothermia. When the storage temperature is close to 0°C, the diseased part can still expand slowly. When the temperature is high at the early and late stages of storage, the disease spread rapidly.
3. Control methods. The prevention and control of Penicillium must be started before the fruit is harvested, combined with comprehensive prevention and treatment measures such as transportation and storage period management, in order to receive good results.
Pre-harvest control. Before spraying the fruit, spray 200 times lime twice (1:2:200) Bordeaux mixture or 25% carbendazim wettable powder 1000 times, evenly spray on the fruit, also can cure anthrax, black Star disease and powdery mildew.
Avoid mechanical damage. This is one of the important measures to prevent the disease. Prevent stab wounds, crushing, and bruising during harvesting, grading, packaging, and handling.
Storage place sterilization. Sterilize the storage area before storage. Acetaldehyde can be used to treat acetaldehyde in the air at 0.5% concentration for 180 minutes, or 1% concentration for 120 minutes, or 2% concentration for 60 minutes to prevent penicillosis.
Dip fruit. Use 25% carbendazim WP 1000 times to dip fruit after harvesting, that is, immersed and immersed for no more than 1 minute, stored after immersion. If 500 times 2,4-D butyl ester is added to the drug, it can not only improve the effect of fruit soaking, but also keep it fresh.