Young walnut trees affected by waterlogging should do a good job of overwintering and cold prevention as soon as possible.

The flood disaster on July 19 not only caused direct damage to trees, but also caused some derivative harm, such as greedy and prosperous young trees, epidemic diseases and so on, which was very disadvantageous for young trees to survive the winter safely. Young walnut trees are easy to dry and die after winter because of their large pith, loose tissue and poor cold resistance, especially the young walnut trees with good soil conditions in the plain area are more prone to freezing damage. To do a good job of overwintering and cold prevention of young walnut trees, we should start with the following aspects:

The first is to control the growth of young trees in the middle and later stages. After the occurrence of flood, the soil moisture is good, and the new shoot growth of walnut in the land with deep soil is large and stops growing late, which is not conducive to the accumulation of tree nutrients. During the period of 1-year-old and 3-year-old young trees, nitrogen fertilizer should not be applied from July to September, and the stagnant water in low-lying land should be eliminated in time to prevent young trees from greedy and prosperous in the later stage. The middle ploughing was carried out in the first and middle of September to cut off the shallow roots of the young trees and restrain the growth of new shoots. For strong shoots that have not stopped growing and whose growth has reached more than 100 cm, measures such as pulling branches and opening corners or coring are taken to force the new shoots to stop growing, and 0.3% potassium dihydrogen phosphate foliar fertilizer is sprayed 2 times from August to September to promote the maturity of branches and buds and improve the frost resistance of trees.

The second is to do a good job in the prevention and control of floating dust in autumn. Floating dust, also known as Daqing leafhopper, is harmful to adults who lay eggs in tree trunks and branches at the end of autumn (September to October). Floating dust laying eggs under the bark will seriously damage the bark, causing the young trees to lose too much water and die. In autumn, there are more floating dust on crops and weeds, especially in intercropping radish, cabbage and other vegetable plots, the damage is more rampant, the rate of killed plants can reach 100%, and the injured trees are bruised all over the body. Intercropping vegetables and tall crops should be prohibited between walnut trees, and 2000 times of imidacloprid wettable powder should be used to control the heavy occurrence of floating dust. at the same time, the trunk and branches of young trees were whitened before floating dust laid eggs (before late September) to reduce the damage caused by floating dust to the tree trunk. The formula of whitening agent: quicklime: salt: water: 6 ∶ 0.5 ∶ 15.

The third is to brush antifreeze for tree protection. From the defoliation of walnut to the end of November, the tree body was protected by antifreeze. The commonly used antifreeze is made by boiling polyvinyl alcohol and water at the ratio of 1 ∶ 15: 20. The trunks and branches of less than 3 years old were evenly coated with polyvinyl alcohol for 1 and 2 times to prevent the young trees from losing water and draining.

The fourth is to fill it with frozen water. It is necessary to fill enough frozen water before the middle of November to meet the needs of water transpiration during the dormant period and to ensure that young trees survive the winter safely.

Li Shizhong, Forestry Bureau of Xingtai City