Author: Fruit Tree Steward
In fruit tree production, some lime water (or mixed agents) is often used to whiten the trunk, the purpose of which is mainly to carry out insecticidal sterilization, thermal insulation and antifreeze, anti-sunburn hazards and pika nibbling on the bark to avoid frost damage during the early spring flowering period.
(1) The role of the whitening agent
Sterilization: The whitening agent contains a large number of bactericidal ingredients, which can play a role in sterilization, preventing bacterial infection and accelerating wound healing.
Insecticide: The insecticidal component in the whitening agent kills overwintering insect eggs and dried moth pests in the bark. Because pests generally prefer black, dirty places and do not like white, clean places, the trunk is painted white, which can prevent pests such as tianniu, giddings, and large green leafhoppers from laying eggs on the branches.
Anti-nibbling: The whitening agent contains lime, sulfur and other uncomfortable ingredients, which can prevent pikas from nibbling on the bark in winter.
Anti-sunburn: In winter, the trunk is black and brown, which is easy to absorb heat, resulting in a large temperature difference between day and night in the bark of the sun, and it is easy to freeze and crack. Large trees, in particular, are more likely to crack because of their thick trunks, dark colors, and poor tissue toughness. After whitening, it can make 40% to 70% of the sunlight reflected, reduce the temperature difference between day and night in the trunk, and the bark is not easy to crack, which plays a role in protecting the cortex and preventing sunburn and frost damage.
Anti-spring freeze: Whitening can slowly increase the temperature of the tree, delaying germination and flowering to avoid frost damage to fruit trees during the early spring flowering period.
(2) Several preparation methods of fruit tree whitening agent
Copper sulfate lime whitening agent: the active ingredient is 1 kg of copper sulfate, 20 kg of quicklime, 60 to 80 kg of water, or the ratio of the three is 1:20:(60~80).
When preparing, use a small amount of boiling water to fully dissolve the copper sulfate, and then add 2/3 of the water to dilute; the quicklime is added to 1/3 of the water, slowly matured, and adjusted into a concentrated lime milk; after the two are fully dissolved and the temperature is the same, the copper sulfate solution is poured into the concentrated lime milk, and continuously stirred evenly.
Lime sulfur tetratherapy coating agent: the active ingredients are 20 kg of quicklime, 2 kg of sulfur, 4 halves of table salt, 4 pairs of animal (plant) oil, and 80 kg of hot water. In the ingredients, quicklime requires white color, light weight, no impurities, such as the use of impure lamina lime as raw materials, to first soak with a small amount of water for several hours, so that it becomes a paste and no particles is the best.
If the granulated lime is applied to the trunk, it will continue to absorb water and release heat on the trunk and burn the bark, which should be paid more attention to for light-skinned or thin-skinned trees. The finer the sulfur powder, the better, it is best to add some neutral laundry detergent, the dosage accounts for 0.2% to 0.3% of the weight of the water.
When preparing, the sulfur powder is dissolved with table salt with hot water of 40 °C to 50 °C, and washing powder is added to the sulfur powder solution. Slowly put the quicklime into water at 80 °C ~ 90 °C, slowly stir and fully dissolve. Mix lime milk and sulfur with water, then add salt and grease, stir well and serve.
Stone sulfur compound quicklime whitening agent: the active ingredients are half a kilogram of stone sulfur compound stock solution, half a kilogram of salt, 3 kilograms of quicklime, an appropriate amount of oil, and 10 kilograms of water.
When preparing, the quicklime is cured with water, oil and fat are added, and after stirring, water is added to make lime milk, and then the stone sulfur compound stock solution and brine are poured, and the mixture is fully stirred.
Paint whitening agent: Paint and water are prepared in a ratio of 5:1, and an appropriate amount of insecticide, fungicide and avoidant are added.
When formulating, the insecticide, fungicide and repellent are first dissolved in water, and then mixed with the paint to adjust the paint concentration to facilitate brushing and stir well. This whitening agent has a long adhesion time, high whiteness, and also treats tree branch diseases and insects, germs and prevents pikas from nibbling on bark, and is better used in areas with serious sunburn hazards.
(3) Precautions
With the use, not for a long time: fruit tree whitening agent should be used with the use, not for a long time. When using, the whitening agent should be stirred thoroughly to facilitate brushing. The concentration of the whitening agent should be applied to the trunk of the tree without flowing, not into knots, not warped after drying, and not falling off. When applying white, be sure to be even, especially the bark gaps, holes, branches and other places to repeatedly paint, so as not to leak brush.
Clean the warped skin and dispose of the branches: Before using the whitening agent, it is best to scrape off the parasites such as the bark and moss, and the tree holes and bark cracks are good places for pests such as insect shell insects to overwinter, and they should also be scraped clean.
If it is found that the branches have been mothed by harmful insects, the pests should be killed first, and then the whitening treatment should be carried out, it is best to cut off the diseased branches, weak branches, aging branches and overly dense branches, and then collect them and burn them centrally, and wrap the cracks and freeze cracks with plastic film.
Timely application, even brushing: The whitening of the trunk is mainly to prevent fruit tree pests from overwintering and protect the fruit tree, therefore, the whitening work must be fully completed before the cold air invades. Whitening is late, pests have been transferred up and down, can not play a barrier role, generally in November to December whitening is more appropriate. When brushing, use a wide brush to dip the whitening agent, and when the temperature is suitable, the base of the main branch and the trunk are evenly whitened.
Whitening height: The whitening height should depend on the size of the tree, usually 0.6 to 1.2 meters from the ground. If the old tree is exposed to the new, in order to prevent the sun, the whitening position should be increased, or the whole plant should be whitened.
Mixing requires caution: Caution should be exercised when mixing insecticides, fungicides and repellents. The whitening agent is an alkaline substance, while most of the insecticides and fungicides are acidic substances, and when mixing insecticides or fungicides in the whitening agent, it is necessary to use fungicides, insecticides and avoidants that can be mixed with alkaline pesticides.
Article Source: Northern Fruit Tree Planting Alliance