Measures for flower and fruit protection of walnut

   aims at the causes of walnut flower and fruit drop, flower and fruit protection is based on prevention, with the combination of prevention, treatment and management. Strengthening soil management, combined with spraying micro-fertilizer and growth regulators, makes walnut growth in a moderate state. External catastrophic weather and irresistible factors should, in principle, give priority to prevention and improve the ability to resist adverse environment by strengthening the tree potential. In addition, it is necessary to cultivate excellent varieties with flower, cold resistance, moisture tolerance and short growth period. The following measures can be taken.

   1. Strengthen the comprehensive management of the orchard and apply more organic fertilizer in the walnut orchard to enhance the tree potential, improve the storage nutrient level of the tree, promote flower bud differentiation, and pay attention to the combined use of nitrogen, phosphorus and potassium fertilizer, which is beneficial to increase the proportion of healthy flowers and reduce the drop of flowers and fruits. Young and prosperous trees apply less nitrogen, increase phosphorus and potassium fertilizer, adult trees use nitrogen, phosphorus and potassium fertilizer reasonably, and apply more organic fertilizer. For trees with a large amount of flowers, topdressing should be carried out at flowering stage and foliar spraying 0. 5% after flowering. 3% urea.

   uses summer pruning as the main method and winter clipping as the auxiliary method to reduce the shade of the tree crown and improve the light conditions. Cut off the weak and dense flower branches in summer, and the remaining flowers should be thinned to concentrate nutrients, which is beneficial to fruit setting.

   2. Keep more flower buds for "small trees" and strong trees with few flower buds, keep flower buds and young fruits as far as possible when pruning, and "stay as soon as you see flowers" when necessary, so that they can bear more fruit, stabilize fruit and bear large fruit, so as to increase yield. Therefore, when shaping and pruning walnuts, don't put too much emphasis on tree shape and cut off too many flower buds.

   3. Flower thinning and fruit thinning are important measures for high yield, stable yield and high quality of walnut trees, so as to make them bear reasonable fruit and avoid too much or too little fruit.

   walnut flower thinning and fruit thinning and flower and fruit protection are all for a common purpose. Flower and fruit protection is to directly take various measures to preserve flower buds and young fruits, and thinning flowers and fruits is to achieve the purpose of "protection" by means of "thinning".

4. Boron spraying at flowering stage and growth regulator boron are indispensable trace elements in fruit trees, which can promote pollen germination, pollen tube growth, ovary development, fruit setting rate and fruit quality. Therefore, spraying 300 × 350 times borax with honey or brown sugar water at full flowering stage of walnut can not only meet the boron needed by the tree, but also increase the stigma mucus and make the pollen grains absorb more water and nutrients, so as to improve the fertilization rate and fruit setting rate. However, it should be noted that borax does not dissolve in cold water but dissolves in boiled water. Before spraying, borax should be dissolved in boiling water before spraying.

Spraying boric acid, rare earth and gibberellin at flowering stage of    could also significantly increase the fruit setting rate of walnut trees. According to the experiment of Shanxi Forestry Science Research Institute, the best concentration of gibberellin, boric acid and rare earth is 54 mg / kg, 125 mg / kg and 475 mg / kg respectively.

The order of the effect of three elements of    on fruit setting rate was gibberellin > rare earth > boric acid. In addition, spraying 0.5% urea and 0.3% potassium dihydrogen phosphate for 3 times during flowering could improve the nutrient status of the tree and put it into fruit setting.