Nursing Care of Citrus trees growing Citrus after being Frozen

After the citrus trees were frozen, the aboveground parts were damaged or withered to varying degrees, while the underground parts were generally slightly damaged. The nursing measures after freezing are mainly to make use of its relatively intact root system to promote its germination of new branches and restore the tree crown as soon as possible so as to gradually achieve the goal of normal growth and fruit. The specific measures include the following aspects.

1. Treatment of frozen canopy. According to the severity of frostbite, according to the principle of timely cutting off the frozen dead part and keeping as many healthy parts as possible, the tree crown should be dealt with timely and appropriately:

(1) if the rolled leaves occur due to mild freezing, part of the rolled leaves should be cut off in time, and about 0.3% urea solution should be sprayed 2 times for 3 times to prevent the expansion of fallen leaves.

(2) if the leaves are frozen and withered but do not fall off, and the shoots do not die, as the withered leaves continue to consume water, they will be expanded and frozen, so the dead leaves should be knocked down, removed or cut off in time to prevent the branches from dying.

(3) if some of the branches have been frozen, it is advisable to cut off part of the frozen branches that can be identified by the naked eye in time, and then thoroughly cut off the frozen dead parts when the new shoots germinate and the boundary between life and death is clear.

(4) for the severely frozen tree, the whole crown has been frozen to death, so it should be sawed off first, leaving the trunk and the base of the main branch not to be treated temporarily, and then sawed to the lower position at the junction of the frost injury part and the health department after the first batch of new shoots are ripe. When a large number of new shoots are sprouted, they should be left as many as possible in order to accumulate photosynthesis and synthesize nutrient and nourishing roots, and 2 or 3 healthy ones are selected from them to promote their branches and form a new crown skeleton.

(5) the branches crushed by snow should be saved as far as possible, and for the torn branches, some branches and leaves should be cut off properly to reduce water consumption, and then it should be aligned in situ, wrapped with plastic film, bound with ropes, and fixed with a bracket. don't untie it until it heals firmly later. If it cannot be saved, it should be sawed off as soon as possible. After sawing dry, the wound surface is larger, should be flattened with a sharp knife, brush protective agent to prevent mildew and promote healing. The protective agent can be made with yellow mud plus fresh cow dung plus 2Hon4Mel D100mg / kg, or with Vaseline (or tarmac) 250g plus carbendazim 5g. According to recent reports, the "Sanling ointment" made of 1 gram of "920", 50 grams of carbendazim and 10 kilograms of vaseline is also very effective in protecting wounds.

2. Strengthen soil, fertilizer and water management. Freeze-damaged citrus orchards generally require that the soil should reduce tillage, fertilization should be light and avoid concentration, and it is best to spray thin foliar fertilizer frequently. From April to July, urea liquid is mainly used, twice a month. From August, phosphorus and potassium fertilizer should be added to the spray liquid. Generally, frost-injured trees are prone to micronutrient deficiency, such as zinc, manganese, copper and so on. The deficiency can be identified according to the newly extracted branches and leaves, and then the trace elements lacking in the tree or multi-micro compound foliar fertilizer such as Yemanbao can be sprayed by means of extra-root topdressing. In rainy and snowy years, especially after the beginning of spring, Rain Water should open ditches in time to eliminate stagnant water to prevent rotting roots. Loosen the soil in time after the weather is fine to prevent soil consolidation and improve soil temperature. In the high temperature and drought season in summer and autumn, attention should be paid to drought prevention and drought resistance, and tree plates can be covered with local materials, which can not only prevent drought and cooling, but also prevent soil erosion.

3. Prevention of cracking of branches and timely prevention of diseases and pests. Frozen orange trees are prone to sunburn in high temperature season due to damage of branches and leaves, exposure of branches, bursting of bark, causing resin disease and anthracnose, and further weakening the tree potential, so it is very important to protect branches. 5 parts of lime, 1 part of limestone-sulfur mixture, 0.1 parts of salt, 0.1 parts of tung oil and 20 parts of water are used to prepare a whitening agent and brush the branches. The newly germinated twigs and tender leaves of frozen trees are precious and vulnerable to diseases and pests, so aphids, mites, scale, leaf miner, butterfly larvae, anthrax and other diseases and pests harmful to new shoots and young leaves should be carefully checked and controlled in time.