What is the reason why persimmon trees all fall off?

1. The degree of physiological fruit drop is related to the fruiting position. On the same tree, there are fewer fruit drops in the upper part of the crown, but more fruit drops in the lower and inner parts, which is related to the different light intensity in different parts. Therefore, if the fruiting branch or fruiting mother branch is located at the top and grows vigorously, the fruit drop is less, while if the fruiting branch is located at the lower part or the branch is thinner, the fruit drop is heavier.

2. On the same fruiting branch, the middle fruiting 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 branches. The middle flower bud differentiated earlier and faster, and the fruit setting was lighter.

Physiological fruit drop mostly occurs from flowering to mid-July, and fruit drop is the most serious before and after wheat harvest, accounting for about 80% of the total fruit drop in the whole year. Individual varieties still have fruit drop from August to September.

3. The main reasons for physiological fruit drop are as follows: 1. Incomplete flower bud differentiation leads to early fruit drop. For example, the same branch mentioned above has the same fruit drop situation. The second is poor pollination. Some varieties do not need pollination, such as large millstones, and varieties with this characteristic are not easy to drop fruit physiologically. However, some varieties, especially most sweet persimmon varieties in Japan, must be equipped with pollination trees, otherwise the fruit will be stunted and the early fruit drop will be serious. The third is the weather. It rains continuously during flowering, which affects pollination and is easy to drop fruit. Fourth, the tree structure is unreasonable. The high and dense branches of trees have poor ventilation and light transmission, which affects the accumulation of organic nutrients in branches and leads to weak growth potential of branches, so the fruits on such branches are easy to fall off. Fifth, there is insufficient fertilizer and water. Long-term dry soil, poor soil, fertilizer and water absorption difficulties, resulting in more fruit drop. Sixth, there is too much water in the soil. The absorption capacity of root system decreases, even if more fertilizer is applied, it will be difficult for trees to absorb and utilize it, and it will also drop fruit because of insufficient nutrient supply.

Second, pests and diseases lead to fruit drop.

1. First, persimmon pests are serious. Persimmon beetles generally eat fruit before and after wheat harvest. The first generation of damaged fruit is not easy to fall off, and it will always hang on the tree, where the larvae pupate and continue to be the second generation of victims. The color of the second generation persimmon fruit changed from yellow-green to orange-red, and it became hard, soft and easy to fall off. The second is the harm of anthrax. It occurs in the late growth stage, usually in September, causing fruit drop.

2. In order to prevent persimmon trees from falling fruit, pollination tree varieties need to be configured first, and pollination trees must be planted or artificially pollinated. Second, girdle the trunk or main branch of the robust tree at the flowering stage, with the width not exceeding 0.5 cm. For the sake of safety, it is best to leave a safety belt or spiral ring cutting to facilitate healing. In addition, the supply of fertilizer and water should be strengthened after girdling. The third is proper pruning, especially in summer, to remove useless and redundant branches and promote ventilation and light transmission. The fourth is to prevent and control pests and diseases, strengthen fertilizer and water management, and enhance tree potential. 5. Spraying 500ppm gibberellin at flowering or young fruit stage, spraying alone or adding 1% urea, has a good effect on preventing fruit drop.