The main diseases during storage
Botrytis cinerea is the most dangerous during the storage process. The fruit is susceptible to the disease in the field. It develops at low temperature (0°C-8°C) and can grow and reproduce at -5°C. Moreover, the grapes have weak resistance to it. The pathogenic bacteria invade the stratum corneum and epidermis through the wound, and the onset is rapid, causing the fruit depressions to shrink, the peels easily broken, a large number of ash or yellow mycelium and spores accumulate on the skin, the internal chemical composition changes significantly, tannins and certain Aromatic substances are destroyed, causing the fruit to lose its commercial value.
Penicillium wilt Penicillium was infested from the wound and natural fracture of the fruit during cold storage at 0°C to 10°C, and spread deep pulp tissue. Rotten berries have a very musty smell. But it does not infect healthy fruits.
Alternaria alternata grapese were infected by Alternaria alternata and developed at 0°C to 2°C. The diseased part was in the fruit stem, the base of the fruit stem and the side of the fruit, which caused the fruit stem to shrink and the fruit to fall. Mycobacterium tuberculosis is susceptible to fruit and fruit stems and occurs at low temperature storage. Rhizopus and black mold occur in the hot season.
The site of infecting D. amylovora in D. abortus was mainly stems of stems and pedicels, and the fruit was not susceptible to disease. The onset of symptoms is similar to that of Alternaria alternata and occurs at 0°C to 2°C with other pathogenic bacteria inhibited. The bacteria can also grow at a temperature of -8°C, but it grows fastest at 24°C and stops growing above 34°C. Uninjured grapes are easily infected by wounds.
Soft rot Rhizopus has a fast pathogenicity, only 24 to 48 hours. The site of infection is mainly fruit. After the hyphae invaded the fruit, the infested areas were first immersed in water-infiltrated plaques, and then the fluids flowed and rotted, the peels easily fell off, and the healthy tissues were rapidly infected. Because the pathogenic bacteria cannot grow at -0.5°C to 0°C, the storage fruits can be stored for several days under high temperature and this disease can occur. The diseased fruit grows with gray bacilli.
Prevention of diseases during storage
Reasonable cultivation and management Reasonable cultivation techniques are conducive to the accumulation of sugar in grape berry, which is the premise to enhance the storage of fruits. Organic and P and K fertilizers should be added, and the use of nitrogen fertilizer should be strictly controlled in the later period. Water should be stopped within half a month prior to harvesting, and reasonable loads should be used to strengthen the comprehensive prevention and control of pests and diseases. In addition, pre-harvest calcium injection can increase the calcium content in the fruit, maintain the hardness of the fruit, enhance the fruit's storability, and improve the fruit's ability to resist decay.
The biochemical indicators for proper harvesting to avoid bumps harvesting at appropriate time are about 18% sugar content, 0.6% to 0.8% acid content, 20 to 35:1 sugar to acid ratio, total pectin and soluble fruit. The ratio of glue is 2.7 to 2.8:1. Appropriate late mining should be carried out to increase the sugar content of the fruit, reduce the moisture content, improve the quality, and ensure the integrity of the protective tissue of fruit stems and pericarps and enhance the toughness.
The antibacterial treatment of sulfur dioxide during storage and disinfection before storage is the best agent for storage disinfection and sterilization. The use concentration should be mastered. Different varieties have different tolerances for sulfur dioxide, and the appropriate concentration must be determined in advance through experiments. Sulfur treatment is generally performed at 20 grams of sulfur powder per cubic meter. In addition, sec-butylamine, peracetic acid, and the like can also be used. During storage, measures such as low temperature, gas regulation, radiation sterilization and chemical sterilization are adopted to create an environment that is not conducive to the growth of pathogens, improve the storage of grapes, and extend the storage period to achieve preservation.
Always inspect the refrigeration system to see if any ammonia is missing. If so, open the warehouse as soon as possible to change the air, spray water to clean the air, and also introduce sulfur dioxide to neutralize the ammonia gas. The concentration of sulfur dioxide must not exceed 1%.
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