How to prevent the empty canopy of Chinese chestnut?

How to prevent the empty canopy of Chinese chestnut? Please introduce the method to cause the empty canopy of Chinese chestnut, in addition to the characteristics of the variety, the main reason is lack of nutrition or lack of boron. The comprehensive control measures are as follows: 1. Improved varieties: improve the varieties of poor chestnut trees with high empty canopy rate and low yield in mountainous areas. 2. Centralized pruning: for trees with empty canopy caused by weak tree potential, the first 1-2 fruiting mother branches are retained during pruning, and the other weak branches are all thinned; the crossed, overlapping, overdense and infruiting branches are thinned or retracted in time. If the fruiting mother branch at the end of the branch is too weak, it should be retracted in time. 3. Increase the application of organic fertilizer: apply organic fertilizer after harvest in autumn to promote the full and full differentiation of flower buds. The amount of fertilizer application should be 100 kg per plant, while 0.5 kg-1 kg of urea and 250 g of biological potassium should be added. If there is not enough organic fertilizer, special fertilizer for Chinese chestnut can be used instead of 4 kg-5 kg per plant. The application method is ditch application, 30 cm wide and 50 cm deep. Pay attention to the mixing of fertilizer and soil into the ditch, and then cover the soil. 4. Pressing green manure: for mountain chestnut trees with high emptiness rate and insufficient source of organic fertilizer, green manure was pressed from late July to early August. As a result, the pressure of each big tree is about 50 kg. The method is to spread the green manure evenly in the tree plate, and then press 5cm-10cm soil on the green manure. If the mountain bark soil is taken nearby, the effect will be better. Pressing green manure can also preserve soil moisture. 5. Skillful use of boron fertilizer ① soil boron application: combined with the application of organic fertilizer in autumn, the big tree applied 100g-200g boron per tree, once every other year. Trees with serious canopy can dig 8-20 fertilizer holes with a depth of 30 cm around the canopy in spring, scatter 100-200 grams of borax in the holes, and then pour a small amount of water to cover the soil after water infiltration. ② foliar boron spraying: spraying 0.3% borax solution once or twice at flowering stage can significantly reduce the empty rate, but the effect is not as good as that of soil boron application. In general, the two methods are used together and the effect is very good. ③ trunk boron transport: in the early flowering stage, a small oblique hole is drilled on the trunk about 1 meter from the ground, deep to the pith, then diluted to 0.5x10 (upper right-6) with 0.5g of available boron, hung upside down on the trunk in an infusion bottle, and then slowly dripped into the tree through a small hole in the trunk with an infusion tube. The advantage of this method is water saving and quick effect. 6. thinning of male flowers: during the period of male thinning, the mixed inflorescence at the apex of the fruiting branch is exposed, and the basal male inflorescence is 4 cm-7 cm long. Artificial removal of male flowers can retain only the apex inflorescence of fruiting branches, and remove the rest (including the lower part of fruiting branches and male inflorescences on male flower branches). Chemical male thinning can be done by spraying tree crown with 1000 times solution of Chinese chestnut androstol in late May, which can drop male 30-40 days earlier, and the male thinning rate is more than 80%. Click to get more chestnut planting techniques click to get more fruit planting techniques