Apple early deciduous disease is the collective name for early flaking of leaves when the apple tree does not reach normal defoliation. It is caused by the hazards of several diseases. The most serious ones are apple brown spot and apple spotted leaf disease, followed by apple gray spot disease and round spot disease. After the occurrence of the disease, it directly affects the normal growth and development of the tree and fruit, and affects the accumulation of organic nutrients and the differentiation of flower buds; when it is severe, it causes the apple tree to blossom in the fall and weakens the tree vigor and reduces the resistance of the tree, resulting in that year, even The second year the decline in apple production and quality. one. Onset of disease The pathogens of apple brown spot and spotted deciduous disease are wintered by mycelium or conidium discs on diseased leaves, shoots or bud scales. After the apple blossoms, the overwintering pathogenic bacteria germinate with the rise of temperature, and then it spreads in the rain and produces a large number of conidia, first dipping into new leaves; there are two peaks of infection in a year: the first time in late April to June. In the first half of the year, the injured leaves in the 20th day of the exhibition were most likely to infect; the disease did not show signs of entering the incubation period after infection, and when the timing was ripe (about the beginning of July), small lesions and disease centers appeared on the leaves; In September, the germs re-infested. In the early stage of disease, brown spots appeared on the leaves, purple halos were around, several lesions were connected at the later stage, yellowing of the leaves fell off in advance, and early leaves were formed. two. There are many causes of early defoliation in apple caused by morbidity, including infectious diseases such as brown spot and spotted deciduous disease, as well as insect pests such as red spider and gold leaf moth. Second, the management is extensive, and the pests and diseases are seriously endangered; the clear garden is not complete, and the diseased branches and leaves carry a large number of pathogenic bacteria for a successful winter. Third, the orchard is confined, the conditions for ventilation and light transmission are poor, and the high temperature and humidity in summer are conducive to the spread and spread of germs. Fourth, weak tree vigor, partial application of chemical fertilizers, and lack of organic fertilizer; can not be applied according to the growth rules of fruit trees, resulting in poor disease resistance. Fifth, circumcision (cutting) is too heavy, especially for trees that have been hacking for years. Early defoliation disease is most evident in these trees. Sixthly, prevention and treatment are delayed. Most of the farmers see no diseased leaves in the field, they do not control or postpone their prevention and control, and they ignore the incubation period of the bacteria. The result is that the drug spray is not used at the last time; the drug is not the right type, and blind control occurs. The phenomenon. three. Comprehensive control measures 1. Strengthen orchard soil water management, scientific pruning, reasonable load, enhance tree vigor, improve the disease resistance of fruit trees; re-apply organic fertilizer, increase phosphorus and potassium fertilizer, is a fundamental measure to reduce the occurrence of disease. 2. Renovation of confined orchards and promotion of thinning; isolation of orchards to implement thinning, generally large orchards have to be remodeled, regardless of the type of tree, after the transformation must meet the requirements of â€œtransmission of light and air, smooth flow between rows, no transfer of branches, convenient operationâ€ . 3. Clear Garden: Combine the winter cuts to cut off the branches and branches of the trees, clean them out together with the ground leaves, and destroy them in a concentrated way to destroy the pathogens that cause overwintering. 4. Chemical control: Because of the latent period of early defoliation, the â€œprematureâ€ word should be embodied in chemical control; three key prevention and control periods should be seized during the whole year; the first is the pre-emergence (mid-mid-March), spraying 5 degree lime sulfur agent. Requires trees, trunks and ground to be sprayed together to eliminate overwintering pathogens. The second time, 7 to 10 days after flowering, a therapeutic bactericide is used, such as 5,000 times for 43% Hollik, 1500 times for 50% Pyronin, or 1000X for 50% Thiophanate. The third time before bagging, use the bactericidal agent for the second time, plus insecticide and calcium supplement. After bagging, choose a protective bactericide, such as 50% Anthai 800 times, or 1% polyoxin 800 times, or 12.5% â€‹â€‹diniconazole 800 times. In the chemical control after the flowering period, attention is paid to the prevention and treatment from May to August. After each spraying, the interval is 12 to 15 days, pay attention to the rotation of medication; in the rainy 6 to 8 months, it is recommended to use 1 or 2 Bordeaux fluids; The number of prevention and control is preferably 6 to 7 times.
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