The tree trunks of green trees and fruit trees in parks, campuses, roadsides and gardens are often painted white in winter. Isn't it very spectacular that they are uniform? Why should the tree trunks be painted white in winter? What's the effect of painting white on the tree trunks?
What is the white paint on the trunk
First of all, we need to find out what white things are. This white thing is the lime water that people add 20 jin to 40 Jin quicklime into 100 Jin water.
The main ingredients of the trunk whitening agent: lime milk, salt, soybean powder and stone sulfur mixture.
Specific preparation method: use 10 kg of quicklime, 1 kg of sulfur powder, 200 g of salt, add 30-40 kg of water to mix evenly, and adjust into paste. Finally, a small amount of basic or neutral pesticides were added to enhance the efficacy of killing pests and diseases. White the trunk from late November to late December.
What is the effect of white paint on tree trunk
First, lime has certain bactericidal and insecticidal effects, which can kill some overwintering fungi, bacteria and pests parasitic on the trunk.
Second, because pests generally like black and dirty places, they don't like white and clean places. When the trunk is coated with white lime water, the soil wrapped pests dare not climb up the tree along the trunk to make trouble.
Why brush the trunk white in winter
The main reason is that most insects can't fly in larval stage and only grow wings after deformation, and the main task of insects after wing growth (development completion) is to mate and lay eggs, when it really harms plants, its larva stage
In this stage, it is not the outbreak season of pests in autumn and winter. At this time, the measures mainly play a preventive role. In winter, some pests on the trees will go down to the ground for winter. In autumn, those pests that can't fly after being brushed with lime won't come down, and they will be frozen to death in winter.
Third, in winter, the temperature at night is very low; in the daytime, when exposed to the sun, the temperature rises, while the trunk is dark brown, which is easy to absorb heat, and the temperature of the trunk rises very fast. This kind of cold and heat makes the trunk easy to crack. Especially for big trees, the trunk is thick, the color is deep, and the tissue toughness is relatively poor, which is easier to crack. After being coated with lime water, because the lime is white, it can make 40% - 70% of the sunlight be reflected off, so the temperature difference between the day and night of the tree trunk is not big, so it is not easy to crack.
In agriculture, lime is often mixed with other things as a pesticide. The famous pesticide "Bordeaux solution" is made by mixing lime and copper sulfate. The main chemical component of Bordeaux liquor is basic copper sulfate, which is a kind of pesticide with strong bactericidal ability.