1. Fruit shrinkage disease
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?1.1 Symptoms of fruit shrinkage disease
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?Apple fruit shrinkage disease is a physiological disease that occurs in the largest area in Fuxin. It mainly harms fruits. In severe cases, branches and leaves will also show abnormalities. According to its symptoms, it can be divided into two types. One is the dry spot type on the fruit surface. Symptoms generally begin to appear on young fruits about half a month after flowering. Brown, nearly round lesions appear on the fruit surface and yellow mucus is secreted. The fruits are deformed and prone to falling off early. One is the pulp cork type. Water-soaked lesions appear in the pulp tissue of diseased fruits, which are brown and spongy, and the fruits are soft.
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?1.2 Causes of fruit shrinkage
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?Fruit shrinkage is caused by boron deficiency. Generally, the occurrence of fruit shrinkage disease is more common in orchards on barren hillside and river beach sandy land. The main reason is that the boron element in the soil is lost by leaching with water, resulting in insufficient boron element in the fruit, thus causing fruit shrinkage disease. In addition, drought and compaction of the soil will also affect the absorption of boron by fruit trees. Fuxin belongs to an arid and semi-arid area, with low organic matter content in desertified soil, low precipitation all year round, and the occurrence of fruit shrinkage disease is relatively serious.
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?1.3 Prevention and control methods of fruit shrinkage disease
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?1.3.1 Improve the soil and apply more fertilizer. Improve orchards with poor soil conditions, apply more organic fertilizers, plant green manure, improve soil structure, increase organic matter content, and enhance water and fertilizer storage capacity. Apply 150-200 g of borax when applying base fertilizer in autumn.
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?1.3.2 Top dressing outside the roots. Spray 0.3% to 0.5% borax solution before flowering, during flowering and after flowering. When spraying after flowers fall, 0.3% urea can be added.
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?2. Microleaf disease
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?2.1 Symptoms of lobular disease
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?Apple tree leaf disease, also called zinc deficiency, is a physiological disease of apples. Symptoms appear in spring: the internodes of new shoots are shortened, the leaflets on the top tips are clustered, and the leaf edges are slightly rolled up. After February to March of the onset of the disease, the diseased branches die. It is generally difficult for diseased trees to bloom and set fruit. Even if they set fruit, it is difficult for the fruit to grow and often appear deformed.
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?2.2 Causes of leaf disease
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? Leaf disease in apple trees is mainly caused by zinc deficiency. Both sandy and alkaline orchards are prone to zinc deficiency. In addition, zinc deficiency is related to the imbalance of nitrogen, calcium and other elements in the soil. Excessive application of nitrogen fertilizer will aggravate the occurrence of leaf diseases.
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?2.3 Prevention and treatment methods of leaf disease
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?2.3.1 Apply more organic fertilizer and plow in time. Improve soil. For orchards on sandy soil, alkaline soil and particularly barren hillside land, organic fertilizer must be applied and attention should be paid to the nutrient ratio of the fertilizer.
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?2.3.2 Apply zinc fertilizer in autumn. When applying base fertilizer in autumn, add 0.5 to 1 kg of zinc sulfate to each adult tree and irrigate after application.
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?2.3.3 Apply zinc fertilizer to the leaves. During the budding period of fruit trees, spray 0.5% zinc sulfate solution or 1500-2000 times micro seedling strength solution once, and spray the second time about 2 weeks after flowering. The effect will be visible in the same year after spraying, and the effect will last for 1 year.
3. Sunburn
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?3.1 Symptoms of sunburn
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?Sunburn, also known as apple sunburn, is a common physiological disease. Symptoms mainly begin to show during the fruit expansion stage, and the disease is more serious in the sparse parts of the leaves, especially on the sunny side. The surface of the infected fruit appears chlorotic and discolored, showing light white amorphous lesions. As the disease progresses, the lesions turn brown and become necrotic, easily forming deformed fruits. In addition, sunburn will also occur on the branches, and the bark will become discolored, spots will appear, and eventually dry up in parts.
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?3.2 Causes of sunburn
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?Sunburn is mostly caused by strong light, high temperature and Caused by drought, it is most common in Fuxin area from July to August when the sunshine is the strongest and the temperature is the highest. In some orchards, the trees are weak and have small branches and leaves. Strong light easily irradiates the fruits and branches directly, and the sunburn disease is more serious.
In some orchards, excessive pruning and lack of leaf shade can also lead to the occurrence of sunburn.
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?3.3 Prevention and treatment methods of sunburn disease
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?3.3.1 Strengthen cultivation management and enhance tree vigor. Through reasonable fertilization and watering, especially the application of base fertilizer in autumn, it is necessary to promote the healthy growth of fruit trees and reduce the occurrence of sunburn disease.
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?3.3.2 Reasonable pruning. When pruning apple trees, special attention should be paid to properly retaining the leaves near the fruit to avoid direct exposure of the fruit to strong light.
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?3.3.3 Fruit bagging. The fruits are bagged half a month after thinning. Appropriate fruit bags can be selected according to the occurrence of apple diseases and insect pests. Remove the fruit bags about half a month before harvesting to facilitate fruit coloring.