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First, the degree of physiological fruit drop of persimmon tree physiological fruit drop varies greatly among varieties. For example, the main plant variety of Taixing Mountain in our province is lighter, which generally does not exceed 10%, which is not easy to detect, and Dahongpao variety After entering the fruiting period, the fruit drop is serious, and the fruit drop rate is up to 2/3.
The degree of physiological fruit drop is related to the result site. In the same tree, there are fewer fruit in the periphery and upper part of the canopy, and more fruit in the lower part and the inner part, which is related to the difference in the degree of light in different parts. Therefore, the result branch or the result of the mother branch is at the top, the growth is strong, the fruit is less, and the result is that the branch is located in the lower part or the branches are weak, and the fruit is heavy.
On the same result branch, the fruit in the middle is the lightest, the top is the second, and the base is the heaviest. This is related to the degree of flower bud differentiation of the branches. The flower buds in the middle are differentiated earlier, and the differentiation speed is faster.
Most of the physiological fruit drop occurred after the flower fell to the middle of July. The fruit drop was the most serious before and after the wheat harvest, accounting for 80% of the total fruit drop in the whole year. Individual varieties still showed fruit drop from August to September.
The main reason for the occurrence of physiological fruit drop: First, the flower bud differentiation is incomplete, causing early fruit drop. For example, the different fruiting conditions of the same branch mentioned above are the same. The second is poor pollination. Some varieties do not need pollination, such as large grinding discs, and varieties with this characteristic are not easy to physiologically drop fruit. Some varieties, especially most of the sweet persimmon varieties in Japan, must be equipped with pollination trees, otherwise the fruit can not develop and the fruit is seriously damaged in the early stage. The third is the weather. It is rainy and rainy during flowering, which affects the fruit drop when pollinating. Fourth, the structure of the tree is unreasonable. The tree is tall, the branches are too dense, the ventilation and light transmission are poor, and the organic nutrients that affect the branches accumulate, causing the tree branches to grow thin, and the fruits on such branches are easy to fall off. The fifth is insufficient fertilizer. The soil is dry for a long time, the soil is poor, and the absorption of fertilizer and water is difficult to cause fruit loss. Sixth, too much soil moisture. The absorption capacity of the roots is reduced, and even if more fertilizer is applied, the tree body is difficult to absorb and use, and the fruit supply is insufficient due to insufficient nutrient supply.
Second, due to pests and diseases caused by fruit drop, the persimmon is seriously harmful. Persimmon is generally harmful to the fruit before and after the wheat harvest. The first generation of the fruit is not easy to fall off, it will always hang on the tree, and the larva will pupate in it and continue to harm the second generation. The persimmon fruit of the second generation is changed from yellow-green to orange-red, and it is easy to fall off when it is hard and soft. The second is the anthrax disease. It occurs in the later stage of growth, and it is usually caused by a large number of cases in September, causing fruit drop.
In order to prevent the persimmon tree from falling, firstly, it is necessary to configure the pollination tree variety, and it is necessary to plant a pollination tree or carry out artificial pollination. Second, the flowering period is to cut the trunk or main branch of the strong tree, and the width should not exceed 0.5 cm. For safety reasons, it is best to leave a seat belt or a spiral ring to facilitate healing. In addition, the fertilizer and water supply should be strengthened after the ring cutting. The third is to properly trim, especially to strengthen the summer trim, remove useless and redundant branches, and promote ventilation and light transmission. The fourth is to prevent pests and diseases, strengthen the management of fertilizer and water, and enhance the tree. The fifth is to spray 500ppm of gibberellin in the flowering or young fruit period, and to spray or add 1% urea, it is very effective in preventing fruit drop.
There are two reasons for the fruit drop of the persimmon tree: one is the physiological fruit drop caused by the physiological imbalance of the persimmon tree itself; the other is the fruit drop caused by the pests such as anthracnose or persimmon. Regardless of the type, it may cause serious economic losses in individual years, with substantial reductions or substantial losses.
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