In the process of top grafting and head changing, most of the branches and leaves that make nutrition are cut off, and only the photosynthesis of grafted new shoots and a few leaves provides extremely limited nutrients, resulting in unbalanced nutrition and malnutrition of the walnut tree as a whole.

In this case, if the temperature is normal in winter and properly managed, there will be no serious problems, and it can be repaired by itself in the second year;

If the management is not good, or if it encounters strong low temperature in winter, the walnut trees, especially the trunk parts, will be severely frozen until they die.

Solution: In the process of grafting, don't cut off all the new branches that haven't been grafted, but leave some supporting branches, which can disperse the excessive nutrition provided by the root system and prevent excessive growth, and also have more photosynthesis to make nutrients flow back to the tree body and root system, greatly improving the cold resistance of the tree body. You can also choose to topdressing some fertile water-soluble fertilizers.