There are many misconceptions and conflicting opinions about whitewashing trees. Some believe that this method of plant protection has long been outdated, someone is confident in its effectiveness. So does it need to be bleached? When and how to do it right? We deal with a specialist.
Associate Professor of the Department of Fruit Growing, Viticulture and Winemaking of the Russian State Agrarian University – Moscow Agricultural Academy named after V.I. K.A. Timiryazev
Whitewash is needed for all fruit plants if they grow in regions with negative winter temperatures and stable snow cover. The treatment protects the trees from being damaged by the sun’s rays reflected off the snow.
– The most dangerous weather, when there is a high risk of getting a sunburn, is a clear sky and the air temperature at night and in the morning is below 10 degrees. Particular attention should be paid to stone fruits, including apricot, peach, cherry, plum, sweet cherry, which are most at risk. In those regions where snow rarely falls and does not last long, for example, in the south of our country, there is no point in whitewashing trees. Very old plants with a powerful and thick bark that are difficult to damage can also do without whitewashing.
What whitewash to choose?
Today, several types of whitewash are sold in garden stores. The main component in them is lime, or chalk. PVA glue, casein glue can also be added. There are also acrylic whitewashes. They hold up best, but there is one drawback. Such mixtures clog the lenticels on the trunk through which gas exchange occurs. And if for adult plants, such blockage is not critical, then young ones, under the age of one year, may suffer. Therefore, it is better not to whiten very young trees, but to wrap their trunks with some kind of non-woven material, for example, burlap. Or overlay with spruce.
Some manufacturers add a copper-containing fungicide to whitewash formulations. It is believed that such processing allows the trees to get sick less, but in reality this is not entirely true. There is an effect, but it is insignificant. Yes, during the winter, fungal spores can be suppressed under the influence of the drug, but in the warm season, fungi will actively manifest themselves. There are also whitewashes supposedly with the effect of protection against rodents. But this is nothing more than a marketing ploy. Rodents calmly eat whitewash, to which components are added that are designed to scare them away.
When should plants be bleached?
The plant is damaged by the sun’s rays from late February to early March. Sometimes a tree can get a couple of burns in January. At negative air temperatures, the compositions do not fit well on the trunk. Therefore, it is best to bleach plants in October in dry and sunny weather.
Spring whitewashing does not carry any benefit and does not make sense. In Soviet times, when on the eve of May Day all the trees in city parks and squares were whitewashed, it was rather a tribute to tradition, a festive aesthetics. To protect the trees, whitewash them only in the fall.
How to whitewash trees?
Whitewash should be applied to the trunk and bases of skeletal branches above the level of the expected snow cover, up to a height of about two meters. Before you start, you can cut down small lower branches to make it easier to work. If there are moss and lichen on the bark, then first they should be cleaned with a metal brush, and then whitened.
What happens if the plant is not bleached?
If you do not whitewash the tree in the fall, there is a high probability of mechanical damage to the bark from low temperatures and aggressive sun. As a result, the so-called windows for diseases, pests, or the mittelium of some fungus will appear. Deep penetrating necrosis may develop. All this shortens the life of the plant, leads to its premature death.
Is there an alternative to whitewash?
Alternatively, you can use a garden bandage, burlap, wrap the trunk, or overlay with spruce branches. But whitewashing is still a more progressive method. The compositions include calcium in liquid form, silicon. If you do not whitewash, then you can spray the trees with the same mixture using special devices. This will also protect against sunburn and pests. But I recommend that amateur gardeners still choose acrylic whitewash, it is affordable and easy to use.