Recently, affected by the cold air from the south, the "late spring cold" has struck strongly. It is expected that starting from the 16th, the country will gradually usher in a large-scale cooling weather, and the Z-high cooling range can reach more than 20 ℃. The cooling has a wide range and a large impact, and the harm to agricultural production has to be prevented.

　　1. what is the cold spring
"Late spring cold" refers to the weather phenomenon in which the temperature suddenly drops and the continuous cold air invades in the later period during the normal rise of temperature in early spring, resulting in a sudden drop in temperature and continuous low temperature and rain. "Late spring cold" usually occurs from the beginning of March to the end of April. At this time, because the spring climate is still in the process of drastic changes, although the temperature rises rapidly, it is easily affected by the cold air going south, resulting in the weather phenomenon of warm and cold in spring.
"Cold in late spring" is a very serious forestry and agricultural meteorological disaster. In agrometeorology, we usually judge the weather phenomenon that the average daily temperature in spring is lower than 12 ℃ and the maintenance period is more than 3 days as "late spring cold". For agricultural production, the occurrence of "late spring cold" means that the risk coefficient of crops has increased sharply.

Damage of Rice Seedlings to Cold in Spring

　　2. the hazards of late spring cold
The occurrence of "late spring cold" mainly harms the new buds and young leaves of plants, young fruits of flower vessels, etc. In severe cases, it may even damage the root system of plants, reduce or no harvest of crops, and even cause plant death. Therefore, it is of great significance for agricultural production to correctly understand and prevent the harm of "late spring cold.
　For the field planting areaWhen the "late spring cold" occurs, rice, peanuts, corn and other crops are in a critical period of sowing and raising seedlings. The sudden low temperature and rainy weather can easily cause the seedlings to fail to germinate and grow normally, and in severe cases, it may even cause rotten seedlings and direct death.
　　for vegetable growing areas,Early spring vegetables are mainly planted in facilities and protected areas. Generally, solanaceous fruits, melons, beans, green leafy vegetables and so on are planted. Due to the large cooling range and fast speed brought by the "late spring cold", it is difficult for the vegetable seedlings to adapt, and the longer the duration, the more serious the harm.
　　For fruit tree cultivation areaAt this time, it is in the budding and flowering period of deciduous fruit trees such as peach, plum and apricot. The occurrence of "late spring cold" is easy to freeze the new buds of fruit trees and poor pollination of flowers, which directly affects the fruit setting rate of fruit trees and causes production reduction and no harvest.

Damage of apple florescence by late spring cold

3. measures to prevent the hazards of late spring cold
1. Preferred varieties:

Seed is the basis of agricultural production, and the contribution of good seed is Z in all factors of agricultural yield. On the crop varieties sown in early spring, it is necessary to select varieties with strong cold resistance to cultivate and plant, or to enhance the adaptability of the plant itself to low temperature by refining seedlings at low temperature.
　　2. Physical measures:
Before the "late spring cold" comes, timely use of irrigation and heat preservation, smoke warming, film coating and other ways to prevent freezing to reduce the cold damage caused by the "late spring cold". For open-air fruit trees, you can prevent freezing by painting white branches and soil covering.
　　3. Chemical measures:
　　(1) Spraying antifreeze:External applicationS-inducerInduce the expression of plant resistance genes, activate the immune system of plant resistance, and improve the resistance of crops to adversity stress. It is suggested that the whole plant should be sprayed with Ziqi before the arrival of low temperature, and it should be used together with Baohua Baoguo. While supplementing nutrient elements, it can also improve the concentration in cytoplasm, enhance the cold resistance of crops, and prevent and reduce the impact of "late spring cold" on crops.
　　(2) Application of stress-resistant fertilizer:After the harvest to the "late spring cold" before the arrival of strengthening fertilizer and water management, supplement the nutrients needed by crops, promote root growth, strong crops. It is suggested to use aiming root flourishing together with vegetable area surface to improve soil environment, provide nutrition required by crops, enhance root growth activity and vitality, promote root growth and improve resistance at the same time, effectively strengthen crops, and prevent and reduce the impact of "late spring cold" on crops.
　　

Spray combination

Application combination

Warm tips:
After the temperature rises and stabilizes at the end of the "late spring cold", the injured organizations should be removed in time, the corresponding cold disaster remedial work should be done and fertilizer and water should be supplemented to provide sufficient nutrition for the germination and growth of new tissues.
Due to the differences in the occurrence time and intensity of "late spring cold" in different places, as well as the different crop varieties, climatic conditions, cultivation and management methods, tree vigor, the above scheme is for reference only.