In order to prevent walnuts from hanging fruit, we must first find out the reasons for hanging fruit, just like we go to the hospital to see a doctor. Only by finding the cause can we prescribe the right medicine and get rid of it. Generally speaking, the main reasons for the failure of walnut are: ① improper planting methods and varieties used; ② Poor pollination and fertilization at flowering stage; ③ extensive management; ④ Malnutrition; ⑤ pests and diseases. Say it one by one. We can compare what causes walnuts not to bear fruit, and we can carry out targeted prevention and control management according to the corresponding prevention and control methods in this paper.
1. Walnut can be planted in two ways, one is improper planting method, and the other is improper variety selection. One is walnut seedlings (seedlings) cultivated by seed sowing, and the other is walnut seedlings (grafted seedlings) cultivated by artificial grafting. In addition, there are early-bearing varieties and late-bearing varieties of walnuts.
Walnut generally takes 2- 10 years to blossom and bear fruit after planting, and the method of planting roots in the morning and evening is closely related to the varieties in the morning and evening.
Generally speaking, grafted walnut and early-bearing walnut varieties can bear fruit as early as 3-5 years after planting, while seedling and late-bearing walnut varieties usually need 6- 10 years after planting to bear fruit normally. In addition, for the natural growth of sown walnuts, not only the fruit setting is late, but also the fruit setting quantity and fruit quality are different; The grafted walnut tree bears early fruit, high yield and good stress resistance, which is more conducive to high yield and high yield. Therefore, for fruit farmers who plan to plant walnuts, it is recommended to use grafted seedlings for planting.
Second, the reason for poor pollination and fertilization at flowering stage is that walnut is cross-pollinated from the same tree and pollinated by wind. The flowering period of male and female flowers is inconsistent, and the pollination and fertilization rate is relatively low. If continuous rainfall, cold weather (such as late spring) or strong wind are encountered during pollination, it will aggravate the problem that female flowers of walnut can not be pollinated or the quality of pollination and fertilization is poor, which will lead to the failure of normal flowering and fruit setting, flowering and fruit dropping of walnut. In addition, if only your family grows walnuts nearby, and there are no walnut trees and orchards around, it will also cause poor pollination and no fruit. This is why many walnuts do not bear fruit. You might as well see if this is the case with your fruitless walnuts.
In view of the fact that walnut is not easy to pollinate, fertilize or pollinate poorly at flowering stage, we can control it by the following methods. On the one hand, we can increase the number of walnut trees planted around or put bees to assist pollination, on the other hand, we can also adopt artificial pollination during the flowering and pollination period of walnuts to improve the pollination quality and fruit setting rate of walnuts at flowering stage.
Operation method of artificial pollination: when the stigma of female flower of walnut is inverted at flowering stage, choose the windless weather at 9- 10 on sunny day. On the one hand, you can dip the pollen of male flowers with a brush, and then gently dip the stigma of female flowers to complete pollination. On the other hand, the pollen of male flowers can be collected, diluted with 3-5 times of talcum powder, put into 2-3 layers of spinning bags, and then put into gauze bags filled with male flowers.
If you don't like the trouble of the above method, you can also pick the newly opened male inflorescence and hang it above the walnut tree to let the pollen dry naturally and complete pollination.
Third, extensive management leads some farmers to ignore or not manage walnuts after planting. For example, the planting land is opaque, the soil layer is shallow and the fertility is insufficient. For example, too much nitrogen fertilizer is used and too much water is used. For example, improper pruning or no pruning will cause problems of walnut trees, such as malnutrition, flourishing fruit trees or long branches and leaves, poor ventilation and lighting environment, which will lead to insufficient nutrition for flower bud differentiation and fruit setting, and then only long branches and leaves will appear.
In prevention and control management, on the one hand, it is necessary to apply base fertilizer early, apply more decomposed organic fertilizer, reasonably control nitrogen fertilizer, apply appropriate phosphorus and potassium fertilizer, spray foliar fertilizers such as calcium and boron during flowering and fruiting, control nitrogen and phosphorus and potassium fertilizer for flourishing trees, apply more organic fertilizer and topdressing in stages, and water them in time after fertilization; On the other hand, it is necessary to strengthen the scientific pruning of fruit trees, especially in autumn, and remove weak long branches, invalid long branches, erect branches, pest branches and overlapping rice branches in time. The newly planted young trees are sparse, and the fruit trees in the fruiting period are mainly cultivated with short branches.
In short: scientific and reasonable water and fertilizer, ensure sufficient nutrients, maintain a good ventilated and light-transmitting environment for trees, reduce ineffective consumption of nutrients, concentrate on the development of flowers and fruits, increase fruiting branches and promote flower bud differentiation.