How to prevent frost damage of Schisandra chinensis

1. Disease symptoms Northeast schisandra production areas occur every year different degrees of frost damage, light branches frozen, heavy caused by the death of the whole plant. The damaged leaves showed irregular small spots at the initial stage, which connected with each other with time, developed into large patches with uneven mottle, the leaves faded and the leaf margin dried up. At the late stage of disease, young shoots were seriously dehydrated and wilted, tissues dried and necrotic, leaves dried and fallen off, and tree vigor weakened. First of all, the influence of temperature, spring schisandra germination, sometimes night temperature dropped sharply, water vapor will condense into frost and make young parts frozen. Frost and terrain also have a certain relationship, due to the large proportion of cold air, low-lying land often than flat cooling amplitude, duration is longer, some schisandra fruit garden due to the selection of frost road, or in the cold air easy to condense at the bottom of the valley, it is easy to be damaged by late frost.

2. The peak period of the disease is from March to May. There is a late frost in May every year in Liaodong mountain area, during which the fruit is seriously frozen. Different schisandra chinensis varieties have different cold tolerance, the earlier the maturity, the weaker the cold tolerance, the greater the yield reduction; tree shape, tree vigor and freeze injury also have a certain relationship, weak trees are more serious than healthy trees; the more mature branches, the higher the lignification degree, the less water content, the higher the cell sap concentration, the more starch accumulation, the stronger the cold tolerance. The damage degree of schisandra chinensis is different with different management measures. The soil moisture is higher, the damage degree of schisandra chinensis is lighter when sprinkling irrigation is carried out, but the damage degree of schisandra chinensis is heavier when no watering is carried out.

3. Control measures ① scientific garden, choose sunny gentle slope or flat garden, to avoid frost and valley, in order to avoid and reduce the harm of late frost. (2) Covering the ground, covering the root of schisandra chinensis with corn straw, etc., preventing soil temperature rise, delaying leaf development and flowering time of schisandra chinensis, and avoiding late frost damage. 3. Smoke and keep warm. After the germination of schisandra chinensis, pay attention to listening to the local weather forecast. When the temperature drops to 1℃ on the night when there is a possibility of late frost, ignite the accumulated wet branches, leaves, sawdust and wormwood, and cover them with 1 layer of soil to prolong the burning time. Smoke piles should be set up around the orchard and on the operation road, and more smoke piles should be set up at the windward according to the wind direction, so that the smoke can quickly fill the orchard.④ Sprinkler irrigation heat preservation: According to the weather forecast, a large amount of irrigation on the ground and spraying water on the canopy of plants can be used to keep warm. 5. Spraying medicine and fertilizer, applying nitrogen fertilizer reasonably in the growing season, promoting the growth of branches, ensuring the healthy growth of trees, and applying phosphorus in the later stage to promote the early end of branch growth, which is conducive to tissue enrichment and prolonging the accumulation time of nutrients, so as to better carry out cold resistance exercise. Spraying antifreeze solution and phosphorus and potassium fertilizer can prevent low temperature of 2~5℃ for 5~7 days.