1、 Freezing injury of Kiwifruit
The areas prone to freezing injury are mainly distributed in river beaches, plots with poor air circulation, low-lying areas and Qinling River Valley, and other areas also have varying degrees of freezing injury.
1. Generally, 1-2-year-old freshly grafted young trees are most vulnerable to freezing damage. At the beginning, the young trees of Xuxiang and other kiwifruit varieties with excessive growth occur more seriously, and the freezing damage of seedling and orchard at full fruit stage is less.
2. The frozen parts are mostly kiwifruit trunk frostbite, mainly within 50cm upward of the rhizome. The frozen parts show longitudinal cracking of the cortex, exudation of tree sap from the frozen parts, the epidermis looks intact, and the endothelial layer browning after scraping. The trees suffering from light frost damage will freeze to death, which will seriously affect the benefit of kiwifruit.
2、 Prevention measures of freezing injury in orchard in winter
1. Apply appropriate amount of warm fertilizer to improve the cold resistance of crop plants.
In winter, an appropriate amount of warm fertilizers such as phosphorus, potassium, boron fertilizer, plant ash, burned soil or soil miscellaneous fertilizer and rotten pig and chicken manure can be added to increase the soil temperature and improve the cold resistance of plants. In addition, 600 times of Wofeng vegetable foliar fertilizer can be sprayed. Apply solid diliwang soil conditioner to improve soil, promote plant growth and improve the cold resistance of crops.
2. Do a good job in plant protection of manor crops to improve cold resistance in winter
(1) Overlay. Before the severe cold, the whole plant can be used to build a grass shed to prevent the cold. The tall kiwifruit can be made into a net cover with waste plastic bags or covered with cold proof materials such as straw curtain to improve the temperature.
(2) Trunk binding. Before the severe cold comes, wrapping the main stem and main technology of kiwifruit tree with straw or plastic film can effectively prevent freezing injury.
(3) Irrigation before freezing: if the drought is serious in autumn and winter, it can be irrigated once before the severe cold. If conditions permit, it can be irrigated again before the arrival of cold air, and the effect is better. Irrigation after freezing: the leaves of crops lose a lot of water after freezing. Irrigation must be carried out immediately to reduce the death of crop plants due to a lot of water loss.
3. Smoke to disperse cold current and frost. Before the low temperature comes or on the night of frost, stack weeds, chaff, sawdust, dry branches and leaves or other fuming substances in the crop land for fumigation. Stack 3-5 piles per mu and burn smoke around 10 p.m. for 6-10 hours.
4. Strengthen field management and do a good job in pest control. Timely cultivation of soil and addition of microbial agents (diliwang) can degrade into the best organic fertilizer for crops, make the soil loose and breathable, and do a good job in clearing ditches and draining stains, so as to facilitate the growth of roots, enhance tree vigor and improve the disease resistance of trees. Timely remove the frozen dead residual plants, yellow leaves and dead leaves, and do a good job in the prevention and control of various diseases and insect pests in winter, so as to make the crops grow healthily.
5. Disinfectant disinfection. For the management of fruits after harvest, it is generally necessary to spray the leaves with fungicides. It is suggested that 300 times of spray should be made. Supplement nutrients, repair wounds and promote healing. Trunk wounds, peeling, ulcers, the need to use Kui Ling Ling brush dry, as far as possible to expand the scope of more than one brush, or high concentration of spray, while with green Kok Ke, wo Feng Su root irrigation effect is better.
6. Apply white antifreeze. After falling leaves, the tree body of the orchard that has been put on the shelf shall be painted white, mainly on the trunk and branches. Whitening agent formula: 10 parts of water + 2 parts of quicklime + 1 part of stone sulfur mixture + 0.5 parts of table salt + a small amount of animal and vegetable oil.
3、 Remedial measures after freezing injury
1. Strengthen pest control. After the occurrence of freezing injury, the tree wound increases and the resistance decreases, which is most likely to aggravate the occurrence of diseases. In order to strengthen the prevention and control of kiwifruit diseases and insect pests mainly caused by bacterial ulcer disease, fluranke, schnaning, thiabendazole copper, copper hydroxide and other chemicals can be used alternately. After the pruning work is completed, the medicine can be sprayed once, and 2-3 times in the early stage (mid February to mid March).
2. If the bark is frozen and cracked, wrap the wound with breathable materials before budding in spring to prevent water evaporation and miscellaneous bacterial infection, so as to facilitate wound healing.
3. After germination of frozen fruit trees, pay attention to selecting and cultivating root sprouts. For frozen necrotic plants, sprouts extracted from the base can be used to cultivate new trunk by splitting after lignification.
4. For some severely frozen fruit trees, the trunk cortex cracked seriously, and the cortex became brown and necrotic, so that nutrients could not be transmitted to the root system. Bridging should be carried out in time to ensure the water and nutrient supply of the upper and lower parts of the tree.