Why are trees falling?
The beginning of our first winter in the Kuban brought us many unpleasant surprises. Snow fell on November 30, wet and a lot. In the morning I had to climb in the snow and brush off the branches. But the young apricot had already broken by this moment. Of course, we attributed this to a snow load. When everything melted, during the cleaning of the site, I saw the broken part of the trunk, and it became clear that the snow only logically completed the work begun by the fungus: the entire trunk was rotted inside. I’ll tell you about this - why trees fall, and how to solve this problem.
Why does the trunk rot?
The answer is simple: because the fungus destroys wood. What kind of fungus is quite specific for each type of wood, although there are generalists too. But the fungus is, again, a certain stage of the tree’s unhealthiness, and it cannot be the root cause. Moreover, most fungi are saprotrophs, that is, eating organics of already dead tissues or excrement.
That is, bacteria must work before the fungi, although they can work at the same time. This is also not the root cause, since bacteria and fungi do not have legs, and they themselves can get to the right place only by accident.
Here, xylophagous insects, carriers of pathogenic microflora of tree species, make their contribution. There are a lot of them, these are cattails, bark beetles, and goldfish, and many others, which populate the wood with bacterial and fungal microflora when laying eggs or with excrement. All other insects can be carriers of bacterial microflora - ants, for example, on the feet of which they do not drag!
But insects are not the root cause, they roam constantly and everywhere, and not all and not always rot trees.
Apparently, the main reasons are still three: damage to the external protection, that is, the bark, a decrease in the general immunity of the tree and a combination of unfavorable factors.
In this case, damage to the cortex must be specific. Anyone who cuts the trees knows that even, without burrs, the smoothest cross section can not be covered with anything. In the wind and in the sun, it will quickly dry up, blocking all the inputs and outputs for pathogens, and the cambium along the perimeter will accidentally build up a roller from the bark. At the same time, if the cut did not have time to dry, warm, damp weather was established, the chances of infection of the wood at the cut site are high.
But cracks in the bark, broken branches, mechanical damage, especially if the weather is warm and humid, insects rush here and there - mushrooms expanse. This is a direct path to infection. Here the tree could survive with powerful immunity, with which, unfortunately, spoiled cultivated plants are not good.
What causes damage to the cortex?
When in spring our young cherry was not covered with flowers, and then with leaves of young cherry, I went to carefully examine the tree and understand the situation. Rot in the lower part of the trunk is visible to the naked eye. Inspection of the remaining trees showed a depressing situation: almost everyone in the lower part had bark damaged.
In the majority, it was overgrown with crustal ridges, but in some, rot was clearly visible. I had to urgently treat. I found out the reason later from the previous owners: damage to the bark with a fishing line trimmer when mowing the grass (!).
I really wanted to believe that such neglect of trees is an exception, and not a rule, until I saw the results of tree pruning from some local residents. Bark torn by ribbons, not fully cut, half-broken branches - I want to cry over such trees! It is not surprising that the oldest apple tree in our area is one continuous hollow. Rather, three, because she has three trunks.
Mechanical damage also includes breaking off branches from wind and snow loads, and from overloading crops.
Gnawing is also a mechanical damage, and due to the structure of the damage, it is extremely convenient for pathogens and inconvenient for treatment.
Cracks in the cortex arise from many causes:
- Frost Actually, with a sharp drop in temperature in early spring or during a warm winter, when frost hit after the start of sap flow. Under normal conditions, the trees are not so stupid that they will not be prepared for winter and the excess juices from the trunk can not be removed in the fall. And in the spring they are in a hurry to live.
- Thermal sunburn - also spring trouble. The sun is very bright, and the tree for some reason has not yet adapted. When we lived in the Khabarovsk Territory, our apple trees were exclusively covering. So, to open them in the spring and not whiten immediately - a guarantee of burns. Although the removal of shelters was confined to cloudy weather, but it did not last longer than two days in the spring.
- Excessive nitrogen feeding: bark does not keep pace with powerful growth.
- In cherries, wood cells grow faster than bark cells. therefore landing in wet places and excessive watering it is generally contraindicated, cracking of the bark will be necessary. Other stone fruits, for which it is better dry than damp, are slightly less prone to similar troubles.
How to treat?
This greatly depends on the stage of damage. Freshly broken branches, or rather, hemp, it is enough just to carefully cut it flush with the trunk or skeletal branch.
Grips are most difficult to treat and it is advisable to detect them as early as possible. If it is not gnawed circularly, there are strips of live bark left, then it is necessary to gnaw itself with a mixture of clay and cow dung with ash (this is one of the best repair putties). If the cambium is circular and with severe damage, you will have to do vaccinations with a “bridge” to save the tree.
Cracks in the cortex must be carefully examined: if the edges of the wound are bright, bacteria with fungi have not yet reached here, it is enough to cover the crack. If the edges are brown, you will have to cut everything to living wood, and then gloss over.
The same thing with old rot - cut to living wood and gloss over.
Treatment is a creative process. For example, one of our young cherries lost the main trunk, but a branch low off the trunk remained alive, quite healthy.
The main trunk to live wood was peeled, anointed. And the lateral, healthy low-branching branch was transferred to its roots - it was covered with earth to a height of 30 centimeters. Now the cherry is healthy and bears fruit.
What does immunity consist of?
Immunity in a tree, like in a person, is composed of congenital (genetically determined) and acquired. In this case, innate immunity, in turn, is divided into passive and active.
Passive - prevents the introduction of the pathogen and its development in tissues. For example, the presence of volatile or phenolic compounds that are toxic to the pathogen.
Active - a manifestation of protective reactions. For example, a hypersensitivity reaction manifests itself in the formation of necrotic (dead) tissue at the site of pathogen penetration or the synthesis of phytoalexins with antibiotic effects. That is, the tree does not stand and does not wait when it is protected or eaten, it is active.
Just like in humans, immunity can be stimulated by “vaccinations” - local weak infection. The tree will connect phagocytosis - intracellular digestion of the mycelium of the fungus or bacteria and become immune to this pathogen. So the acquired immunity is formed.
As in humans - the more pathogenic attacks are reflected, the stronger the immunity. Overfeeding immunity reduces, "greenhouse" conditions, too.
Only if in humans the intestinal microflora provides most of the immunity, then in plants is the soil. And the richer and more diverse the soil microbiome is, the healthier the plants will be. By the way, their fruits will be more useful.