Do We Need To Scrape Off Lichens From Tree Trunks In Our Gardens?

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

In late autumn, when the foliage has fallen, the garden becomes empty and sad. And it immediately becomes clear that the branches and forks of the apple trees are covered with lichens. These lichens are especially noticeable when the weather is wet. At this time they are blissful: they have fluffed up, curled up, blossomed with blue silver. And when the snow falls, it seems that the apple trees are dressed in blue fur coats.

What are lichens ? Are they useful or harmful? From the reference literature I learn that this is one of the groups of lower plants, which are a symbiosis (cohabitation) of fungi and blue-green algae. Under a microscope, it can be seen that on a cut, the body of a lichen is represented by colorless mushroom filaments, between which are scattered green balls of algae with a bluish tint. This cohabitation is mutually beneficial. The mycelium of the fungus absorbs water and mineral salts dissolved in it, providing the algae with ideal conditions for existence, and organic matter is formed in the cells of the algae - the main food. Lichens absorb moisture, mainly rainwater, dew, fog.

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In favorable times, reproductive organs appear on the lichen's body, which give millions of spores carried by the wind. These disputes are everywhere. Germinate when they encounter algae. In addition to disputes, there is another, spare, way of reproduction: along the edges of the lichen blades, tiny, like dust grains, lichens are formed - algae cells planted on the filaments of the fungus. Wind or rain, sweeping away or washing away, moves them to a new place of residence.

Lichens vary in appearance. There are so-called scale deposits - in the form of plaques or bolls that grow closely into the surface of a tree, stone or other "object". There are leafy - lamellar, scaly, which are attached to the object with bundles of mushroom hyphae. There are also bushy ones that grow only at the base.

Having settled on the bark of trees and shrubs in large numbers, lichens, according to scientists, "… often cover the bark lentils, which impede the flow of air to the inner parts of the tree." It even happens that individual branches of apple trees dry out. And I also read: “… settling on the bark of trees, they create favorable conditions for the reproduction of harmful insects. Over time, the crust becomes rough, covered with cracks, excess moisture accumulates under it. This means, scientists say, lichens can harm.

Before writing this article, I deliberately walked through my autumn garden. And then I discovered that almost all of it was infected with lichens. They grow on apple trees and pears, on viburnum and mountain ash, on lilac and jasmine, on red and black currants, on oak, cherry plum and cherry, on blackberry, maiden grapes, and even on a peeled wooden post that has been leaning against the wall of a shed for many years … But before I did not notice this. Lichens, it turns out, grow only where there is clean air. This means that my garden is ecologically clean, and it pleases.

I looked closely at these very lichens to determine whether they are very harmful to my garden. For reliability, I armed myself with a magnifying glass, and for good reason. I saw that they, these lichens, are very intricate and fantastically beautiful, I admired them for a long time. I carefully looked for pests under them. Did not find. She peeled off the gray flakes from the branches, looked: did they spoil the bark? The bark under the lichens turned out to be smooth, clean, without cracks and rot. Of course, on old trunks, the bark is cracked, and there is rot, but all this is also where there are no lichens.

I look at my White filling apple tree. She is about fifty years old. Yields such that the leaves are not visible - the whole is covered with apples. But now the harvest was harvested, the leaves fell, and it became clear that she was all wrapped in lichen. To clean or not to clean? I stand in front of her with a scraper and think. Recently, scientists have found that some species of lichens, fighting with competitors, secrete complex substances that inhibit the growth of other plant organisms. So, they can inhibit the growth of the apple branches on which they settled? Well, it turns out that they are enemies to themselves if they oppress the bitches on which they sit. I look carefully, and on the apple tree - not a single dry branch. This means that lichens do not harm them. And there is practically no scab on apples. But on the neighboring apple tree, which is cleared of lichens, there is scab. Powdery mildew was even noted.

On other apple trees - the same picture. It turns out that lichens protect the tree from these diseases. However, this observation was made on only a few apple trees, and scientists are observing hundreds of apple trees, so their observations are more reliable. By the way, it was recently found that lichen acids inhibit the growth of fungi that destroy wood. And this clearly benefits the apple trees. Lichens not only love moisture, they are also very light-requiring. They grow slowly and only where they do not have shading fast-growing rivals. For this reason, tree trunks are their favorite place. In the middle of the crown, you can always find a place where there is enough light, in addition, a humid microclimate is maintained there.

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Recently I was able to get acquainted with the works of one of the largest specialists in the physiology of lichens, Irina Aleksandrovna Shapiro. "Can epiphytic lichens absorb substances from tree bark?" She asks. And he answers: “The data available at the present time (1991 - LB) indicate that there is no direct dependence of the chemical composition of epiphytic lichen thalli on the composition of the crust”. Everything is clear and clear. So there should not be any dry twigs on apple trees from lichens. Although this issue is still insufficiently studied, some complex relationships between lichens and the substrate are not excluded by scientists.

And one more interesting result of the research: the ability of lichens to absorb gaseous and solid substances from the air, in particular, radioactive substances, was noted. Bushy lichens are especially active in this respect, and leafy lichens are weaker. Consequently, lichens cleanse their habitat from radioactivity. Lichens accumulate and retain radioactive isotopes for a long time. So you don't have to destroy the lichens growing on the trees in your garden. They are radioactive garden orderlies. If you have already scraped them off the trees and burned them, do not use their ash as fertilizer for edible plants.

I examined all my apple trees, on which lichens were fluffed up after the autumn rain, and did not find any dried twigs and branches. And no pests climbed into them for the winter. But, I think, these lichens will protect my apple trees from the drying winter frosts, if they suddenly happen. And the yields on these apple trees are high. So I decided for myself: let lichens live in my garden. I will not scrape them off. If they interfere with someone, then you can spray sleeping apple trees with a 3% solution of ferrous sulfate (300 g per 10 liters of water). There are recommendations in the literature to use a 5% solution of ferrous sulfate. Or spray the trunks with a solution of oxalic acid at a concentration of 1: 8. After such treatment, lichens curl up, turn black and fall off.