Before embarking on any work, in my opinion, it is important to understand why you do it, and what processes occur in this case. And it does not hurt to keep in mind the consequences of your actions. So today I wanted to share my thoughts on such a controversial gardening operation as whitewashing trees. I think 99% of gardeners have done it at least once in their lives. In this article we will analyze what benefits spring whitewashing of trees (and does it bring?), and what can replace it with.
In my school and student years, this was, in general, an obligatory procedure, and during the so-called "Leninist subbotniks", which means at the end of April. But to be honest, even then I began to be tormented by "vague doubts. Well, yes, it looks nice and smart, but in answer to the question "why?" the teacher quite reasonably answered - to kill insect pests. Though all sorts of insects were already flying in the air around the already blooming trees (it was in the south).
Later, seriously interested in gardening and reading the literature, I learned that whitewashing also kills disease spores, is a means of protecting trunks and scaffold branches from frost bites. And it should be done twice - in the fall and spring. In general, I read a lot of different things, but the real work in the garden has put everything in its place, at least in my head. So, in order.
Whitewashing against pests and diseases
It is well known that with the onset of the cold period many insect pests, and useful ones too, get crammed into the cracks of the rough bark of mature trees and overwinter there perfectly. Some lay their eggs right on the smooth young bark. These eggs are protected by a thick shell and survive the winter well. The spores of many diseases can also overwinter on the surface and in the crevices of the bark.
So whitewashing in the fall may well be beneficial. But only if you clean the old bark a bit before whitewashing, removing only the easily removed parts of the bark, and then ... WARNING! Whitewash the whole tree, from the ground to the top. After all, if you only whitewash, as my neighbor does, to a height of 1 meter, you will kill all the wintering "parasites" at this height. And the rest perfectly survive and in the spring will begin their harmful activity.
Therefore, to combat them and developed various drugs and methods, more or less effective. For example, late autumn eradication and early spring spraying with strong solutions of insecticides and fungicides on naked, dormant trees.
For those who do not know about eradicating spraying see the article Where garden pests winter and how to spoil their life?
Whitewashing as protection against frost bites
For those who do not know, frost bites appear when nature experiences sharp day and night temperature variations. Usually, this is late winter-early spring. Everything depends on region and climate, there are places where it may occur in the height of winter.
The essence of the phenomenon is that in the daytime the rays of the bright sun fall at the right angle to the dark trunks and branches of trees and warm them strongly. And after the sun goes down, the night frost takes over. Such temperature changes can reach up to 20 degrees. The bark of the trees is like that song: "It is thrown from the fiery furnace into the freezing cold..." And as a result of the sharp difference in temperature it bursts.
What does whitewashing have to do with it? Gardeners are trying to somehow smooth out this temperature contrast, to make it less painful for the trees. We can not reduce night frosts, but it is possible to reduce the heating of trunks and branches during the day, by applying a layer of something white, reflective.
And it is possible to protect from heating selectively, only vertical boles and branches, which are at an angle of about 90 degrees to the rays of the low winter sun and which are strongly heated.
Now, having understood what whitewashing of trees is really for, it is worth discussing when and with what it is better to do it.
When to whiten?
Since the process of frost boles occur mainly in the late winter-early spring (everything depends on the region), it is logical to whiten trees just before the onset of this period, approximately in early February. But it is not physically possible everywhere.
It is good if your garden is in the southern region where there are thaws, and you can get to the tree, and it is recommended to whitewash in positive temperatures. But in northern regions, where fallen snow lies around trees as a thick layer and frosts don't let the trees go for a day, whitewashing should be done in advance, since autumn.
Please also read this.
For more details read article Autumn whitewashing of fruit-trees.
In addition, in southern regions as well, whitewashing from autumn allows you to sleep well and not to worry that you missed the right moment. Here's just one, but a big problem. Ordinary lime whitewash will not last on the bark until the right moment, and most likely by the end of winter there will be no protective effect from it.
What to whitewash?
There are different variants of whitewash. Some use lime, some more gentle chalk, some add clay, straw and manure to create a more durable coating. Someone adds copper sulfate as a fungicide to combat pathogens, someone brings in the usual "grandfather's" whitewash element of modernity - PVA glue. Such whitewash, really, holds up well all winter. And someone boldly uses white water-dispersion and acrylic paints from construction stores.
Despite the fact that all these recipes, emphasis is placed on the durability of coverage, but no one is interested in how the tree feels under a layer of clay or a film of PVA glue. After all, as I said, it is desirable to cover the whitewash and the trunk, and all the branches that are potentially in the risk zone, and this is a large area.
The tree needs air exchange with the environment, and all coatings to some extent reduce the air exchange. All these whitewash - not natural, but introduced by man.
But in garden stores you can find and special garden paints, namely designed with all factors - not to harm the tree, providing air exchange, and hold on the bark from fall to spring. I will not list the names, so as not to create advertising and anti-advertisement, come in, ask about it.
By the way, a separate line is a dispute about the need to whitewash young seedlings. Some claim that they have vulnerable young bark and it is necessary to protect it by whitewashing, and their opponents base their arguments on the tenderness of young bark and categorically advise not to whitewash it. © gardenbarn
Is there an alternative to whitewashing?
Where is the way out? And the solution is very simple and logical, in my opinion. The same garden stores sell special garden bandages made of non-woven material. Being white, they will reflect the sun's rays well, not allowing the bark to warm up, but they also let air in - the bark "breathes".
You say, expensive... But you do not buy for one season. Well, you can easily replace the old (can be new) agrovoloknom, cut into long narrow strips (like bandages) and wrap them around the boles and the necessary branches of the tree. I have been using this way for several years, and with the same strips.
It protects not only from the formation of frost boles, but also from rodents (hares). The only thing you will need to do is to check occasionally that such a bandage covers the bole all the way to the ground. Simple thick paper or cardboard, burlap or cloth will do as a sun screen, such protective layer is enough for one winter.
The main inconvenience is that during thaws they can get wet and they need to be removed and dried. As a last resort, you can lean a wide board to the southern side of the bole, which will cover from the sunlight.
In general, there are many options. And now that we understand what we need whitewashing in the garden, it is already easier for us to make the right choice.