How to protect walnut trees from the cold? A detailed guide to cold-protection techniques for walnut cultivation

Because walnut tree branches have a large pith and high water content and poor cold resistance, they are prone to freeze damage in the colder and drier areas of the north, causing branch dieback. Therefore, to ensure the normal growth of young trees and prevent freeze damage, winter cold-protection work should be strengthened to reduce the harm. Several cold-protection measures are introduced below for growers' reference:

Cold-protection measures can be carried out after the walnut tree loses its leaves (generally from mid-November to early December).

1. Burying in soil for cold protection: For 1- to 2-year-old young trees that cannot safely overwinter in the open field, bend the entire tree body to one side and cover it with soil. This is the most effective and most reliable measure for preventing shoot shriveling.

2. Mounding soil for cold protection: Build a mound of soil within a 30 cm range around the base of the seedling to prevent freezing injury to the root crown and graft union. Remove it after temperatures rise and stabilize in the following spring, and level the tree basin.

3. Whitewashing for cold protection: Whitewashing young trees can alleviate the temperature difference between the sunny and shady sides of the trunk, and the cold-protection effect is relatively good. It can be applied before the soil freezes. The formula for the whitewash is: 0.5 kg salt, 6 kg quicklime, 15 kg clean water, then add an appropriate amount of adhesive and the residue of lime-sulfur mixture and apply it evenly over the young tree's trunk and branches.

4. Coating the trunk with polyvinyl alcohol: Evenly brush the main trunk of the seedling with prepared polyvinyl alcohol. The method for preparing polyvinyl alcohol is: generally use a ratio of “polyvinyl alcohol:water=1:15-20” for preparation. First heat the water to about 50°C, then add the polyvinyl alcohol (do not wait until the water boils before adding it, otherwise the polyvinyl alcohol cannot fully dissolve and the solution will not be uniform), stirring while adding, until it boils, then simmer over low heat for 20-30 minutes. Use it after the temperature drops to where it is no longer hot to the touch.