Apple rough skin disease, also known as ring disease, mainly harms branches and fruits. Branches infected, will form a knob-like protrusion or near-circular necrotic spot centered on the lenticels; on the fruit, the disease will form brown rot spots. In recent years, due to the implementation of bagging technology, the disease rate is relatively low, but the incidence on the trunks of many producing areas is serious, which seriously affects the tree vigor, yield, benefits and longevity of the tree. The same species, the same disease, in the demonstration park established by the author, there are few cases of disease. The reason is that there are great differences or misunderstandings in terms of cultivation philosophy, key points of management, and prevention and control. Here, the author describes the main causes of serious diseases and key technologies for disease prevention as follows: First, the law of occurrence of diseases The germs mainly passed through the winter in the branches, and began to move in the spring, continuing to harm the branches. When the temperature reaches 15°C and rainfall occurs, conidia begin to develop and spread to the branches and fruits with the wind and rain. In May and July and August when the rainfall exceeds 10 mm, or the air relative humidity is greater than 75%, the number of spores in the field will increase sharply. The infected spores will start to germinate under suitable conditions of temperature and humidity, mainly from lenticels and wounds. Intrusion. In August and September, the shoots will begin to develop the tumor-like lesions that formed after the infection. The incidence of old and weak trees and weak branches is heavy, and the incidence of young trees and strong trees is light. Second, the main cause of serious illness After the investigation, it was thought that the causes of apple scab, which was severely scraped and cured year after year, were the following except that the Red Fuji varieties belonged to susceptible varieties. 1. The overall management level is not good. If the amount of sticks is too large, it will reach 90,000 to 120,000/mu; the tree will be overloaded and there will be a large annual output of orchards from 3500 to 4000 kg/mu; too many fertilizers and nitrogen fertilizers and organic fertilizers will be insufficient. . Most of the parks have serious phenomena of large or small size, with orchards closed, poor ventilation and light transmission, serious leaf disease, early defoliation, undeveloped branches, low nutrient storage, weak tree vigor, and widespread fruit smuts. occur. 2. Improper use of drugs during the key period. One is that the interval between medications is relatively long, and it does not pay much attention to the temperature and humidity at that time. Mostly, after spraying, it is necessary to spray the medicine every half month before the bag is put on. After bagging, the fruit is considered "insured", even if the interval between the bactericidal agents is increased to 30 to 40 days, it will not affect the control effect. In July and August, it is the season of high temperature and high rainfall. It is not only the peak period of spore release and transmission, but also the suitable period for transmission of pathogens. If the control is not in place, many germs will inevitably be re-infected and re-infected. The second is that the pesticides that are sprayed are pesticides that have a shorter duration of efficacy. 3. Improper branch shave treatment. One is that the curettage is not timely. When there are obvious nodules or near-circular necrotic spots on individual trees, most of the fruit growers failed to pay attention in time, delaying the optimal timing of prevention and control, and quickly spreading the whole park. The second is that the curettage is not in place. Individual parks neither scratched the spot nor applied medicine. Even though the curettage treatment was mostly scraping dry stems and main lateral branches, the lesions of other larger branches were often ignored or omissions. The relevant studies have shown that the pathogens in the lesions on the branches from 2 to 6 years old have the strongest reproductive transmission. The third is too deep and heavy. Many farmers think that the heavier the scraper, the better the effect. In fact, this is not the case. Excessive scraping will cause damage to the skin and even layer formation. In case of bad weather, such as spring cold, it will naturally weaken the tree vigor and cause more serious infection. Fourth, the collection and destruction of lesions and residues are not in place. Some did not pay attention to the collection and burning of the disease, and piled diseased branches in the garden so that the bacteria left the tree and left the park. It was still a source of re-infection. Third, the key control technology 1. Strengthen comprehensive management. One is to keep the appropriate amount of branches. Regardless of the type of tree, after winter cutting, the amount of leaves per acre should be 55,000 to 70,000; during the growing season, the sprouting branches, legged branches, competing branches, and dense branches should be removed in time to make the orchard pass. Good permeability. The second is the management of scientific fertilizers, and the use of organic fertilizers and chemical fertilizers. If the strain produces 100 kilograms of apple trees, if high-quality organic fertilizer can guarantee 1 tonne per acre, apply 1.5 kg of chemical fertilizer with an effective composition of 50% per year per plant. The third is a reasonable load. The yield of trees in full fruit trees should be controlled between 1500 and 2500 kg. Fourth, the timely drainage in the rainy season to prevent the tree from suffering. Fifth, the soil with heavy soil or acidified soil should be adjusted and improved by increasing organic fertilizer, mixing sand and soil, or applying appropriate amount of lime (75 kg/mu). Sixth, there are boron deficiency symptoms should be added to the appropriate amount of boron fertilizer. Spray 0.3% borax before flowering, flowering and after flowering, or 50-150 g borax before flowering. Because apple, especially Red Fuji apple, is highly sensitive to boron, boron deficiency will directly affect its disease resistance, and lack of boron, excess manganese absorption, or acidification of the soil can easily lead to apple tree rough skin disease, and also cause the pulp to appear corky brown spots. . 2. Do a good job of prevention and treatment in the key period The period from flowering to bagging is a critical period for controlling various diseases of apples. The interval between spraying fungicides is 10 to 13 days. During the period, combined with rainfall, corresponding measures were taken. When the continuous rainfall exceeds 10 mm, spraying must be stepped up, which can have a multiplier effect. Suitable pesticides include thiophanate-methyl, carbendazim, No. 1, diniconazole, and mancozeb. After bagging the fruit, you must not think that the bag of fruit can not be sprayed with fungicide. Because the bagging only acts as a barrier to infection by the bacteria, it does not block the infestation of the branches by the bacteria. Moreover, most of the bagging work is completed before the end of June. In July and August, the high temperature and rainwater are both the peak period for transmission of spores and the appropriate period for the spread of germs. Therefore, this period not only can not relax the prevention and control of pathogens, but also attaches great importance to control 1:2:200 times Bordeaux fluid-based, spray 20 to 25 days. If you still spray other fungicides, the interval should be 10 to 15 days. Among them, in the middle of July and the end of August, heavy rains are the most important aspect of prevention and control. At the same time, it should also be noted that if the weather forecast has heavy rain or heavy rain, or the season of frequent heavy rain over the years, it is not appropriate to spray Bordeaux mixture and replace it with other fungicides to prevent phytotoxicity. 3. Timely scientific cure. The best prevention and treatment time in the life cycle of semolina is when there are nodular rough skin or necrotic spots on individual trees. The best cure time in a year is when the temperature reaches 15°C before and after sprouting. Lesions can also be applied directly without scratching, and can be coated with 3 to 5 times liquid spinach quick-ring or ringworm No. 1. If you want to scrape, you can use a knife to scrape half from the top of the lesion. Collect the sick and burn it in time. After scraping or applying branches, or spraying the whole tree. Apply to the branches, apply 20 times liquid rot to cure or 30 to 50 times the liquid 50% carbendazim; if spraying the whole tree, before the bud can be sprayed 200 times carbendazim or tablet sulfasulfuron; after germination Spray 500 times carbendazim. 4. Try and use suede technology with caution. Some fruit growers have used raccoon technology to cure rough skin branches during the growing season of fruit trees and have achieved ideal results. However, the author suggests: In an orchard with a high level of comprehensive management, this law should not be used blindly. If you want to use this method, you should pay attention to the following points: First, to grasp the time of fur, from late May to early June is appropriate; Second, the first 10 days before the fur must be watered once; Third, the use of cardboard and rope wrapped after suede to Conducive to the production of new skin. Rainwear is
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In recent years, why is the occurrence of apple rough skin disease?