Eight key points should be paid attention to in the cultivation of high-yield walnut with symptomatic application of technology.

Walnut is one of the important dried fruits in China's export. The price of walnut has been on an upward trend in recent years. Therefore, there are broad prospects for the development of walnut. In cultivation and management, techniques should be applied to the symptoms.

Grow walnut

Fruit field selection: walnut is a deep-rooted tree species that likes temperature, light and wind. As the saying goes, "Walnut full of jujube from the wind". The walnut orchard should choose the ecological area with flat terrain, deep soil layer, leeward to the sun, convenient transportation, pure water quality and no pollution. The PH value should be between 6.05 and 7.05. Do not choose abandoned land, continuous cropping land and saline land with a salt content of more than 0.25%.

The planted fruit is grafted seedlings: walnut seedlings propagated in general begin to bear fruit in 6-8 years, and it takes 20 years to enter the full fruit stage. The grafted seedlings generally bear fruit after 3-4 years, which is more than 3 years earlier than the seedling. Therefore, in order to shorten the juvenile period of walnut, improve the economic benefit and increase the income of fruit growers, early fruit grafting should be selected to propagate seedlings.

Select quality products: be sure to choose excellent varieties with early results, strong adaptability, high kernel rate, thin core and shell, easy kernel extraction and high oil content. At present, the better varieties are Luguang, Fenghui, Xiangling, Liaohe No. 1, Yuanfeng, Bo Jinxiang, Linhe No. 1, No. 2, Xifu No. 2, Zhonglin No. 1, 8518, Xifu Lufeng, Jinboxiang No. 1, No. 2, No. 3, No. 4 and so on.

Overcome the phenomenon of "hermaphroditism": the flower of walnut is unisexual and monoecious. The blooming time of male and female flowers of some varieties is different, which is called "dioecious" phenomenon, which affects the fruit setting rate. Therefore, it is necessary to match pollination trees to achieve mutual pollination and fertilization and improve fruit setting rate. In general, the ratio of main varieties to pollination trees is 5-8:1. For example, Xiangling with Xilin 2, SIFU 2 with Lu Guang, etc.

Spring grafting to "release water": walnut compared with other fruit trees, the survival rate of grafting is not high. The main reason: walnut rootstocks and scions contain tannins, which are easy to oxidize to form a dark brown isolation layer in the presence of air, which hinders the communication of cellular substances between scions and rootstocks. The grafting in spring is the last stage of walnut injury. Bleeding can restrain the physiological activity of the grafted cells and hinder the reduction of tannin oxidation condensates. In order to improve the survival rate of grafting, the lower part of the grafting interface should be "released". Generally, young trees should be carved at 10-20cm under the interface, with a length of 1-1.5cm, reaching to the xylem. The general big tree should carve 2-3 crossings in the lower part of the interface, the length and depth are the same as above. In this way, the wound flow can be cut off and the survival rate of branch grafting in spring can be improved.

Pruning should avoid the bleeding period: the bleeding period is from the fallen leaves of the walnut to before germination. If the pruning is carried out, the wound will be so traumatic that it is not only difficult to heal, but also easy to cause premature senescence of the tree. Therefore, pruning should avoid the bleeding period, generally from autumn fruit harvest to before defoliation (Cold Dew) or after leaf expansion in spring to young fruit expansion period.

Pay attention to the cold protection of young trees: young walnut trees have poor cold resistance and are easy to freeze to death. Therefore, we should do a good job of overwintering and cold prevention. The methods of preventing cold are coating white, covering film, burying soil and so on. On the other hand, the effect of burying the earth against cold is better. The method is: after the general defoliation, before the soil thaws, slowly bend the seedling, make its top contact with the ground, cover the wet fine soil 30-40cm, and firmly, cover the dry fine soil about 5cm, remove the soil before germinating in spring next year, and then straighten the seedling.

Correctly deal with the phenomenon of "inverted pull" capturing the back branches: after the walnut trees bear fruit, the upper dorsal branches of the main and lateral branches will become weaker, and the dorsal branches will flourish quickly, forming the phenomenon of "inverted pulling" of the main and lateral branches. If it is not treated for a long time, it will extend into a drooping branch for many years, grow fast and consume a lot of nutrients, so that the upper branch and the back branch of the original branch will gradually dry up and die. Therefore, the back branches should be handled correctly. Treatment method: one is to cut the drooping part at the branch to improve the angle of the branch. Second, if the lower vertical angle is small, the growth is moderate, and the full buds have been formed, they can be temporarily retained and cut off after the results. Third, if the sagging is serious, it should be removed in time when there is no ability to produce results or few results.