What practical measures are there for cold and frost protection in lychee and longan?
Cold and frost protection measures for lychee and longan
1. Whitewashing the trunks
In conjunction with orchard cleanup, whitewash the main trunks and main branches of lychee and longan trees once, which both protects against cold and disinfects. Method for making the whitewash: 10 parts quicklime, 1-2 parts salt, 2 parts adhesive (such as clay, grease, etc.), 2 parts lime sulfur concentrate, 35 parts water; a small amount of a targeted insecticide may also be added. First slake the quicklime with water, filter out the residue, pour in the already dissolved salt, and finally add the lime sulfur, adhesive, etc. and stir thoroughly. When applying the liquid, its thickness should be appropriate, so that it does not run off during brushing and does not warp or peel off after drying.
2. Wrapping the trunks
The root crown at the base of the trunk is the part with the weakest cold resistance; therefore, before frost arrives, wrap the trunk and main branches with rice straw, then apply high earthing-up. Only after temperatures rise the following year should the earth be removed and the straw untied, so as to reduce the day-night temperature difference and thereby reduce the degree of frost damage.
3. Earthing up the tree basin
For young trees, earthing up for protection is the most effective and reliable method. Specifically, with the trunk as the center, build a bread-shaped mound of soil with a radius of 50 cm for young trees and more than 100 cm for mature trees, and a height of 30-50 cm; first place a layer of rice straw or plant ash in the tree basin, then cover with soil, so as to achieve frost protection and moisture retention.
4. Spraying water on the leaves and irrigating the roots
Before frost arrives, do the irrigation work well to increase the soil's water content and prevent the temperature near the ground from dropping suddenly and causing frost damage. During frost, water should also be sprayed on the leaves before the sun comes up in the morning to wash off the frost, so as to prevent the leaves from being frostbitten when the sun comes out and the frost melts.
5. Chemical treatment
2-3 weeks before frost arrives, antifreeze agents, Nash 778 cold protection agent or other cold protection chemicals can be sprayed on the leaves, once every 7 days, for 2-3 consecutive sprays, to improve the cold resistance of the leaves. Paclobutrazol can also be used, but it must not be used continuously, so as not to affect flowering and the sprouting of spring shoots the following year.
6. Smoking the orchard
Mix the weeds and turf mud collected during winter orchard cleanup and pile them in low-lying places prone to frost. On nights when frost arrives, when the temperature drops to the critical temperature at which lychee and longan suffer frost damage, light the smudge fires at the windward side, and set up multiple ignition points, striving for even distribution and mastering the ignition time well, so that the smoke can cover the entire orchard before sunrise.
7. Covering the canopy plus smoking
In the evening when frost arrives, cover the entire canopy with plastic film or 90% shade netting, and only start smoking after 10 p.m.; the next day, after the sun comes out and the frost and snow have melted, remove the film. Repeat this until the frost period ends; this can both prevent frost from directly harming the tree and raise the tree's temperature, and is the most ideal comprehensive cold protection measure.
In conjunction with orchard cleanup, whitewash the main trunks and main branches of lychee and longan trees once, which both protects against cold and disinfects. Method for making the whitewash: 10 parts quicklime, 1-2 parts salt, 2 parts adhesive (such as clay, grease, etc.), 2 parts lime sulfur concentrate, 35 parts water; a small amount of a targeted insecticide may also be added. First slake the quicklime with water, filter out the residue, pour in the already dissolved salt, and finally add the lime sulfur, adhesive, etc. and stir thoroughly. When applying the liquid, its thickness should be appropriate, so that it does not run off during brushing and does not warp or peel off after drying.
2. Wrapping the trunks
The root crown at the base of the trunk is the part with the weakest cold resistance; therefore, before frost arrives, wrap the trunk and main branches with rice straw, then apply high earthing-up. Only after temperatures rise the following year should the earth be removed and the straw untied, so as to reduce the day-night temperature difference and thereby reduce the degree of frost damage.
3. Earthing up the tree basin
For young trees, earthing up for protection is the most effective and reliable method. Specifically, with the trunk as the center, build a bread-shaped mound of soil with a radius of 50 cm for young trees and more than 100 cm for mature trees, and a height of 30-50 cm; first place a layer of rice straw or plant ash in the tree basin, then cover with soil, so as to achieve frost protection and moisture retention.
4. Spraying water on the leaves and irrigating the roots
Before frost arrives, do the irrigation work well to increase the soil's water content and prevent the temperature near the ground from dropping suddenly and causing frost damage. During frost, water should also be sprayed on the leaves before the sun comes up in the morning to wash off the frost, so as to prevent the leaves from being frostbitten when the sun comes out and the frost melts.
5. Chemical treatment
2-3 weeks before frost arrives, antifreeze agents, Nash 778 cold protection agent or other cold protection chemicals can be sprayed on the leaves, once every 7 days, for 2-3 consecutive sprays, to improve the cold resistance of the leaves. Paclobutrazol can also be used, but it must not be used continuously, so as not to affect flowering and the sprouting of spring shoots the following year.
6. Smoking the orchard
Mix the weeds and turf mud collected during winter orchard cleanup and pile them in low-lying places prone to frost. On nights when frost arrives, when the temperature drops to the critical temperature at which lychee and longan suffer frost damage, light the smudge fires at the windward side, and set up multiple ignition points, striving for even distribution and mastering the ignition time well, so that the smoke can cover the entire orchard before sunrise.
7. Covering the canopy plus smoking
In the evening when frost arrives, cover the entire canopy with plastic film or 90% shade netting, and only start smoking after 10 p.m.; the next day, after the sun comes out and the frost and snow have melted, remove the film. Repeat this until the frost period ends; this can both prevent frost from directly harming the tree and raise the tree's temperature, and is the most ideal comprehensive cold protection measure.