Detailed Explanation of Key Points for Frost Protection Techniques in Citrus Cultivation

For fruit trees that have suffered relatively severe frost damage, adopt tree-preservation measures: First, mound soil to increase temperature. Mounding soil protects the root crown; the standard for mounding is that the root system is not exposed and the root crown is covered. Second, whitewash and wrap the branches and trunk. The trunk and main branches form the tree framework and are prone to frost damage, which leads to weakened tree vigor, and in severe cases the bark splits and the whole tree dies. The whitewash is usually made by mixing 10 jin of lime, 1 jin of sulfur powder, 0.2 jin of salt, a little cooking oil, and 30-40 jin of water. Wrapping the trunk with rice straw or coating it with mud gives a relatively good frost-protection effect; when wrapping, make sure the straw heads press down the straw tails and tie tightly, and do not let water accumulate inside the straw and freeze. Third, smoke generation. This mainly prevents heavy frost after freezing, can reduce radiant heat loss, and alleviates frost damage. Smoke-generating materials can be sourced locally, such as weeds, branches and leaves, etc., 4-6 piles per mu. Frost generally appears in the early morning, and ignition for smoke should be timed before the critical temperature for frost damage. Fourth, spray an anti-transpirant thermal insulation agent. The insulation agent can form a molecular film on the leaf surface, inhibit water evaporation, reduce water loss from leaf cells, and achieve a frost-protection effect. Fifth, strengthen intertillage and soil loosening, apply more fertilizer, prevent waterlogging, prevent drought, and control pests and diseases, so as to restore tree vigor as quickly as possible, and pay attention to controlling the outbreak of gummosis after freezing.

For fruit trees that have suffered relatively light frost damage, it is likewise required to do a good job in pest and disease control and water and fertilizer management. For slight freezing, with leaf curling and yellowing and weak growth, immediately use 0.2% urea + 0.2% potassium fertilizer or 0.2% monopotassium phosphate for foliar fertilization 2-3 times; after early spring, apply spring fertilizer earlier; according to the principle of “pick leaves for minor injury, prune branches for moderate injury, saw off trunks for major injury”, treat the tree canopy.