Citrus frost damage occurs to varying degrees almost every year, and orange orchards should do a good job of antifreeze

Citrus frost damage occurs to varying degrees almost every year, and orange orchards should do a good job of antifreeze

Cao Liyun

Citrus frost damage occurs almost every year to varying degrees, especially the periodic frost damage of citrus is a devastating frost damage, which causes more obvious damage to the citrus tree body, even if it encounters a low temperature that is not serious in winter, it is also very easy to bring serious frost damage to the orange garden. Therefore, orangeries should do a good job of antifreeze.

1． The tree tray is covered with soil

Citrus jelly occurs in the low-temperature atmosphere of the orange garden near the ground of about 30 cm, the root neck of the citrus in this low temperature layer is the worst part of the frost resistance, and the soil temperature in the edge area of citrus can be maintained at not less than 0 °C when there is snow cover, so the high-culture soil can be used to effectively protect the tree. In general, the citrus tree body should be cultivated from early to mid-December, and the thickness of the soil should be 30 to 40 cm. Do not take soil from the edges of citrus trees to prevent damage to the root system, and the appearance of ditches will cause root frost damage due to snow and water. If possible, the surface of the orange orchard or citrus strip tree tray should be covered with straw, straw, weeds, green manure, etc. at the same time to reduce the radiative heat dissipation of the ground. For the canopy of young orange trees, it can be covered with straw and film.

2． Bundle branches and set up triangular sheds

For young trees aged 1 to 3 years, in mid-to-early December, three bamboo poles are inserted around the orange tree, and then the outer straw is added to the south. For 4-8 year old trees, the canopy is large, and the branches can be tightened with grass ropes, so that microclimate conditions are formed in the canopy, and at the same time, the ice and snow are prevented from splitting branches, reducing the adverse effects of low-temperature ice and snow days.

3． Barriers are set up to protect against cold

Before the cold wave comes, grass curtains, mats, plastic film and other things can be used to set up temporary wind barriers in the windward outlet of the orange garden to block the invasion of the tree by the cold wind, and the cold protection effect is significant. The wind barrier should be higher than the tree body, and the width of the obstacle depends on the width of the wind surface.

4． Fill the water spray

Before freezing (6 to 10 days before freezing according to meteorological forecasts), irrigation, combined with clear ditch drainage or trenching soil, irrigation along the ditch, limited to no staining on the ground, or according to the size of orange trees, each plant irrigated 100 to 250 kg. According to the measurement, 1 ton of water can release 80,000 kcal of heat when frozen, so that the temperature is stored with water, so that the ground temperature during the cold wave remains relatively stable, which is conducive to increasing the temperature and thus reducing the frost damage. However, in years with heavy rain and snow, ditches should be opened to improve soil permeability so as not to aggravate frost damage. After citrus fruit picking and before the germination of spring buds, each spray once a pine resin mixture 8 to 10 times liquid, or 40% culling phosphorus and motor oil emulsion with water 1:50:2 500 times liquid; for general overwintering mites, mediators and pathogens, it can be sprayed with 2 to 3 degrees of Baume stone sulfur compound or oil emulsion 50 to 100 times liquid before the germination of spring buds. The original insect (disease), as well as the overwintering butterflies, leaf curling moths and other pests of insect pupae, combined with grass to brush off the branches of the blowing cotton, red wax, etc. Tianniu larvae often overwinter in the trunk, can be lime, clay into a paste or dipped in a cotton swab dipped in waste diesel to block the hole to suffocate its larvae and die.

5． Bandage white

Before the thaw (usually in December), wrap the main trunk, main branches and some side branches of the orange tree with straw dipped in mud, or use 40 kg of water, 10 kg of quicklime, 1 kg of sulfur powder, and a little animal and vegetable oil, stir well and brush the trunk white. If you wrap it with straw, when the tree is tied, the top of the straw is tightened on the trunk with a rope, spread out below, and do not tie the grass tightly to prevent the trunk from freezing and being frost damaged. After the next spring warms up, the unpacking and centralized destruction can not only prevent the tree from being frosted and cracked, reduce frost damage and sunburn, but also coat the borers of the tianniu and gidding insects and prevent resin diseases, as well as burn the wintering pests hidden in the bag.

6． Smoke in the garden

According to the weather forecast, when the temperature of the orangery may drop to -3 °C (sweet orange), -7 °C (Wenzhou mandarin), the smoke piles are evenly laid out in the orangery, 4 to 6 piles per mu (1 mu = 667 square meters). Each pile of firewood and grass is about 20 to 25 kg, and all the combustion materials that can emit smoke, such as dead branches and leaves, weeds, straw, chaff, sawn wood, etc. can be used, ignited after 4 p.m., extinguished after sunrise the next day, and the antifreeze effect is very obvious. When this technical measure is adopted, fire prevention should be done well.

7． Sprays and thermal insulation

The first is to spray biogas slurry to protect the body temperature of the tree. Spraying the canopy with the upper clear liquid of the biogas fermentation tank before freezing can effectively prevent frost damage. The second is the foliar spraying of "petroleum steam suppressant", "sixteen pure fog", "Changfeng No. 3" and other steam suppression insulation agents. Before the arrival of the cold wave, the canopy is carefully sprayed with a petroleum vapor suppressant of 30 to 40 times, and the application concentration of "Sixteen Pure Mist" and "Changfeng No. 3" is 3%, and the validity period can be maintained for 20 to 30 days. It is usually sprayed once in mid-December and once in early January. After the evaporation inhibitor spray, a layer of polymer film can be formed on the surface of the branches and leaves, thereby reducing the transpiration of the leaves, reducing the evaporation of water, preventing frost damage, and suffocating the red spider wrapped in the membrane. Or spray 0 before freezing. 1～0． 3% calcium oxide has an anti-frost effect.

8． Shake the snow to guard the branches

Shake off the snow on the branches in time when it snows. The snow under the canopy is removed before freezing, placed outside the canopy, and the orange grove is drained, the branches torn by the ice and snow are cared for in time, the torn branches are supported back to the original growth site, and the cracks are coated with "Three Spirit Cream" (made with 5 grams of "920", 20 grams of carbendazim, and 50 grams of petroleum jelly), and then tied with plastic tape to promote the healing of the cracks.

9． Post-freeze recovery measures

The first is leaf preservation. Leaves are nutrient storage organs, photosynthetic factories, more leaves, more hope to restore the tree momentum and increase production. Spray 1% urea once on a sunny day after freezing to protect unfrozen leaves. The second is fertilization. After freezing, each adult fruit tree is subjected to 5 to 10 kg of human manure and urine fertilizer, or sulfur-containing compound fertilizer 0. 5 kg. At the same time, the canopy spraying high-efficiency compound fertilizer, each small packet of water added 10 kg, the effect on the restoration of tree potential is good. The third is timely pruning. When budding, shear (saw) remove the frozen branches or large branches to prevent the frozen branches from spreading downwards. The large branches of the saw should be mixed with yellow mud, salt and flour, and then sealed at the wound of the saw to prevent germs from invading the xylem and cracking in the sunburn on sunny days. The fourth is to strengthen the prevention and control of diseases and insects. After frost, the resin disease of citrus and red spiders are prone to outbreaks, and it is necessary to use insecticides and fungicides to control diseases and insect pests in time to promote the healthy growth of citrus.