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The cause and prevention of early deciduous apple
Editor's note: Apple's early defoliation disease occurred in many orchards, either heavy or light, and many farmers came to inquire about solutions. Recently, Dong Shengyong from South Guanzhuang Village, Qinghan Town, Gucheng County, said that they had apples there, covering an area of ​​670 acres, mainly red stars and red Fuji apples. The fallen leaves are beginning to fall every year in August, and the leaf rate is very high. I am looking forward to giving guidance to the experts. In order to solve the readers' problems, we invite Apple expert Qin Li to write the following. The early deciduous apple seriously affects the growth of the tree and its fruit. Early defoliation reduces the production and accumulation of organic nutrients and directly affects flower bud differentiation and late fruit development. When severe, it causes the apple tree to fall in the second flowering season, weakens the tree vigor, and reduces the tree resistance, causing the year, even the second year and the third. The apple's output and quality declined. There are many causes of early defoliation in apple trees, including early defoliation caused by infectious diseases (brown spot, grey spot disease, round spot disease, and spotted deciduous disease, etc.); , Early leaf loss caused by leafhoppers, etc.; Early leaves lost due to lack of tree elements, such as iron deficiency, causing young leaves and leaves to lose their chlorosis, yellowing, and severe leaf loss and loss; early management of leaves caused by improper management, such as spraying When the drug is used, the concentration of the drug is arbitrarily increased, unqualified pesticides containing harmful substances are used, and the liquid mixture during spraying is inhomogeneous, so that the leaves produce phytotoxicity and cause early defoliation; excessive use of quick-acting fertilizers (especially nitrogen fertilizers) and organic fertilizers. Insufficient input, the balance relationship between the nutrient elements in the tree is destroyed, affecting the absorption and utilization of certain elements and causing early defoliation; the bad environment can also cause early defoliation, such as high temperature and drought in summer, when the temperature is above 34°C, if the orchard The low soil moisture content can not meet the demand of the tree, and the imbalance of physiological regulation of the tree leads to self-leafing of leaves and early defoliation; continuous rainy days After the rain the weather is fine, because the blade can not adapt to the climate mutation, causing dry leaves and cause early defoliation (this phenomenon is reflected in the outstanding Golden Delicious varieties); adverse orchard crown density, air and light, can also cause early defoliation. In addition, due to the difference in disease resistance among varieties, the occurrence degree of early defoliation diseases varies greatly among varieties, such as the ability of Matsumoto Jin and Meng to resist early defoliation. The reasons for the prevention of early defoliation of apples should be clearly identified, and targeted measures must be taken to achieve good results. Completely remove diseased leaves in the autumn and burn them centrally or deeply. The spraying season should be sprayed in a timely manner, and it can be sprayed with Heine, Polaroid (Polyoxin, Kesheng) and so on. The general year will spray 4 to 5 times. Prevention of spider mites can be used Qi Qi Su, Qi Ling, and so on. Pear nets can be used to prevent pyrethroids, imidacloprid and other. Be sure to apply pesticides at the effective concentration range and minimum effective dose stated in the pesticide. The trees with poor ventilation and light transmission should be reshaped so that the light transmittance of orchards can reach 35% to 40%. During the growing season, top dressing should be increased or decreased according to the age, vigor, fruit set, cultivation conditions, and fertilizer types. Do not over-fertilize and pay attention to fertilization methods in order to ensure that the tree is balanced. The orchard water management should be timely irrigation (maintaining 60% to 80% of the orchard soil moisture content) during drought, and arranging quickly after the flood season. (Shijiazhuang Orchard Research Institute, Provincial Academy of Agricultural Sciences)
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