Longan loves heat and tolerates heat but not cold; how can it overwinter safely?
Longan overwintering
1. Cultivate robust autumn shoots.Autumn shoots are the fruiting mother branches of longan for the next year and are also one of the main branch shoots for longan overwintering; whether the autumn shoots are robust or not determines whether the tree can overwinter safely. Therefore, the last autumn shoots of longan are generally best sent out in mid to late October. Before sending out the shoots, it is best to apply a light nitrogen fertilizer and water, so as to send out the shoots uniformly and strive for all autumn shoots to mature in early to mid December. Robust autumn shoots can enhance the accumulation of nutrients in the tree, thereby effectively resisting cold spells.
2. Do a good job of winter orchard cleanup and trunk whitewashing.(1) Remove dead branches and diseased leaves: after the autumn shoots mature, spray with 0.9-1.2 degrees Baume lime-sulfur mixture to control overwintering pests and diseases. (2) Trunk whitewashing: use 10 kg of quicklime and 1 kg of sulfur powder, add 30-40 kg of water, stir evenly, and mix into a paste; brush the main trunk and the first- and second-order branches. This can effectively reduce freezing injury.
3. Mound soil around the tree base.In combination with winter orchard cleanup and deep plowing, spread pond mud, turf, and the like within a 100 cm diameter around the tree base for mounding, up to 10 cm above the trunk graft union, which can effectively protect the graft union.
4. Straw mulching and binding.(1) In winter, within a 120 cm diameter around the tree base, cover with 10-15 cm of straw, corn stalks, rapeseed stalks, etc., or cover with plastic film, which can raise soil temperature. (2) Use straw to bind the trunk and the first- and second-order branches, which can play a role in keeping the tree warm.
5. Irrigate the orchard.Before the temperature drops, lead water into the orchard and irrigate the whole orchard, then drain immediately after irrigation. Where there are no irrigation conditions, carry water to pour over the tree base; for adult longan trees, pour 100-120 kg per tree. This can replenish the tree's water, increase soil and air humidity, raise soil temperature, and reduce freezing injury.
6. Smoke the orchard.Before the cold spell arrives, prepare flammable materials such as rice husks, sawdust, and turf in the orchard, placing 1 pile every 10 m, mixed with a small amount of waste diesel, which can increase smoke and heat. After 10 p.m. on the night the cold spell arrives, light the smoking materials, using smoke to raise temperature and keep warm to prevent frost damage.
7. Spray water to prevent freezing.If wet freezing occurs, manpower should be organized quickly to shake off the ice blocks on the longan trees and spray water to thaw them.