Why do we need leaf fall?
Leaf fall is an evolutionary process of preparation for seasonal climate changes, necessary for the survival of a plant in nature. With the onset of cold weather, most of the flora sheds its summer decorations and enters a state of suspended animation. Metabolic processes in plant life systems practically stop.
On a note!
Leaves, so necessary in the summer for evaporating excess moisture and collecting life-giving sunlight, simply become unnecessary and fall off.
Leaves fall - tree's defensive reaction
Trees look different in each season of the year. This is due to the presence of chlorophyll in the leaf blades. In spring and summer there is a lot of it, so the process of photosynthesis occurs actively due to the long daylight hours. And closer to autumn, the amount of water in chloroplasts decreases, the process of photosynthesis becomes impossible and chlorophyll is destroyed. The leaves become yellow or purple in color. And the presence of cork fabric at the base makes them fragile. That is why a light wind can easily tear off the leaves, and they begin to fall in the fall.
Leaf fall is the plant’s protection from moisture loss. Water is simply necessary for the tree to survive the winter. The evaporation process in some plants occurs more slowly, so the leaves do not fall until winter. This is facilitated by essential oils or the presence of a mucous substance that fills special passages in the veins. Gardeners note that leaf fall is a biologically necessary process for the development and growth of perennial plants.
Why are there green leaves on the trees?
As night and day temperatures decrease, the soil under the trees cools. Less moisture and nutrients reach the roots. The plant receives a signal to produce the phytohormone ethylene, which is responsible for the separation of leaves. This element enters the separating (palisade) layer, which contains chlorophyll, which is responsible for the green color. The supply of nutrition and moisture stops, chlorophyll is destroyed, the leaf turns yellow or purple, and then separates from the branch.
Ethylene gas is rightly classified as a plant hormone, because it:
- synthesized inside the tree and in extremely low concentrations regulates its growth;
- activates fruit ripening;
- causes aging of leaves and flowers, falling of leaves and fruits;
- participates in the response of plants to various stress factors and in the regulation of many other important events in their life.
Ethylene, or more precisely, ethylene producers, are compounds whose destruction is accompanied by the release of gas. If it does not arrive on time due to hormonal imbalance, the leaves continue to receive a minimal amount of nutrition and moisture. Due to cool weather, the stomata on the foliage, which are responsible for respiration, are closed, and evaporation does not occur. The leaves have not completed their life cycle and have not died, they are simply sleeping.
On a note!
At the hormonal level, the plant did not receive the signal to produce ethylene in time - this is the main reason why the apple tree does not shed its leaves for the winter.
Sometimes it happens that one plant receives a signal, but the other does not. Failures in the development of trees occur selectively, just like in humans. One fell ill due to weak immunity, and the other did not, although they were in the same conditions.
Common gardening mistakes
Unfortunately, summer residents notice too late that apple tree seedlings are unprepared for winter. In the fall, they start going to the dacha less often (due to bad weather), and after harvesting root crops they stop altogether. The result: we arrived at the dacha after the first snow to cover the flowers, and there was a green garden. So what should I do?
If snow has already fallen and the leaves are frozen, then it is better to do nothing and hope for a mild winter. It would be a mistake to take the pruning shears and cut off the frozen leaves or, even worse, to pick them off by hand. This will not help the apple tree in any way, you will exhaust yourself and leave damage to the young bark at the place where the petiole is attached. You should not pick off leaves even in the fall before frost, since they are only a sign and not the cause of low winter hardiness. If it is still possible to build a shelter for apple tree seedlings, then this will be more useful.
For an adult apple tree, overwintering with leaves and unripe growth is only fraught with freezing. Young trees and seedlings may die from frost or dry out in early spring. Therefore they require special attention.
Some gardeners recommend treating apple tree leaves in the fall with a high concentration of pesticides in order to provoke a discharge. This measure is unacceptable, since the tree gets severely burned, and the leaves fall off as a result of severe stress. Such “help” will negatively affect the winter hardiness of the apple tree. It is possible to treat with chemicals, but they must have a specific purpose. We will look at them below.
What drugs to use to shed leaves
Agricultural enterprises spray trees with synthetic inhibitors (defoliants) to inhibit growth and remove leaves from apple trees. Made from ethylene, they cause artificial aging of wood and leaf fall. They are used, without exceeding the dosages specified in the instructions, at the beginning of natural leaf fall. If you treat an apple tree with outdated toxic drugs “Desitrel”, “Gromadin”, “Etaphon”, magnesium chlorate, there is a high risk of damage to the growing point, deterioration in the viability and death of the plant.
On a note!
Forcing a tree to shed its leaves using chemical compounds in an individual plot is a dangerous undertaking.
In nurseries growing apple trees for industrial purposes, the drug “Sitrel” or copper chelate is used to prepare seedlings for the upcoming digging. Their action is due to the presence of silicon in the composition. Treatment is carried out only after spraying the plants with preparations that contain sulfur compounds. Moreover, the effectiveness of such a defoliant depends on the weather during the growing season and the resting phase, the current state of the plant.
What to do if the apple tree does not shed its leaves in the fall
To avoid problems with leaf fall in an apple tree, you can use the following recommendations:
- Start planting seedlings on time, without delaying. Then the young apple tree will have time to prepare for the cold weather.
- Choose the right varieties for planting in the current climate. The best option is to buy seedlings from local gardeners.
- Don’t forget about fertilizers and the rules for applying them. If planting is carried out in the fall, add potassium and phosphorus, and in the spring you can use both organic matter and nitrogen fertilizers.
- Discard leaves by moving your hand from bottom to top. Weak and dry leaves will fall off. Not to be confused with pruning.
- Whitewashing the trunks and main branches of the apple tree. It is necessary to have time before the first frost.
Advice! You can also help the tree by covering the root circles with a layer of peat, pine needles, and mown grass about 10 cm. The optimal time is the first light frost. Then in the future you won’t have to suffer and wonder what to do with an apple tree that has not shed its leaves.
You can cover the trunk with some material, such as agrowool or burlap.
What actions can you take?
Winter sometimes brings severe frosts. Therefore, regardless of whether all the foliage has fallen, it is necessary to carry out the necessary work for apple trees:
- First of all, whiten the trunks and lower branches of apple trees to protect them from pests.
- Place mulch under the apple tree in the fall and insulate the root area with a 10-centimeter layer of dry branches, bark or humus.
- Wrap young seedlings with burlap or other covering material to prevent freezing.
The leaves of late varieties of apple trees begin to fall much later than those of early ones. It can fall off or fly around in strong winds even at the end of November.
Leaf fall has not started - how to fix the situation
If leaf fall does not begin at the usual time, and in the fall the apple tree stands with leaves , it means that it is not ready for winter. Having analyzed in detail all the work that was carried out with planting apple trees, you can find out the reason for the delay and avoid mistakes next year.
What to do:
- observe the timing of planting the seedling, taking into account the climate of the area - the young tree must take root well and become stronger before the onset of cold weather;
- choose zoned varieties adapted to the local climate;
- Use fertilizers with nitrogen only in spring; in the second half of summer and autumn, add phosphorus-potassium mixtures;
- before the onset of autumn frosts, whiten the trunk and skeletal branches to reduce the risk of damage by parasitic insects;
- pour a layer of mulch 10 cm high in the circle around the trunk when it is time for frost (a fallen leaf cannot be used - infectious agents and pest larvae are preserved in it), wrap the trunk and skeletal branches with covering material, burlap - this will protect the apple tree that has not shed its leaves from frost ;
- build a shelter for short trees that remain with leaves, and wrap the seedlings completely.
All work is carried out in advance in order to eliminate the situation when the leaves on the apple tree do not fall in the fall. To force it to shed its leaves before winter sets in, special preparations are used.
What means to reset leaves will help: features, price, how to force
If the apple trees have not dropped their leaves for the winter before October, they need help. It is not recommended to make physical efforts; this will only harm the tree. For this purpose it is worth using specialized tools.
Superphosphate
This component can be purchased within 100-200 rubles. It is necessary to prepare a solution from it in a ratio of 1 kg per 10 liters of hot water. Mix the liquid thoroughly and then spray.
Fallen leaves
First, the leaves on the trees change color. It is in autumn that we see the whole palette of leaves: from yellow and crimson to dark brown shades. This happens because the process of supply of nutrients in the leaves slows down and then stops completely. Fallen leaves contain carbohydrates, which are produced when the leaf absorbs CO2, nitrogen and some minerals. Their excess can harm the plant, so when the leaves fall, harmful substances do not enter the tree’s body.
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Experts assure that fallen leaves should not be burned, since during this process a number of air pollutants are released into the atmosphere:
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- sulfur dioxide;
- carbon monoxide;
- nitrogen;
- hydrocarbon;
- soot.
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All this pollutes the environment. The very importance of leaf fall for ecology plays a big role. Fallen leaves are rich organic fertilizer and saturate the soil with useful substances. Also, leaf cover protects the soil from low temperatures, and for some animals and insects, leaves are a rich source of food, so fallen leaves are an integral part of any ecosystem.
But there are a few really important points in preparing your site for winter.
- Carrion should not be left under fruit trees and bushes. It is better to dispose of it not in a compost heap, but to bury it deep in the ground somewhere to the side;
- fallen leaves will have to be removed if the garden this season has suffered from scab, coccomycosis, powdery mildew or other diseases whose pathogens persist on the leaves. It is not advisable to place leaf litter from diseased trees in a compost heap. Of course, within a few years, during the process of decay, the pathogenic foci and pathogens of these diseases will die, but it is still better to burn it;
- Leaves should not be left on the lawn. Under the snow they will turn into a compress, which will greatly damage the lawn grass. At the end of the massive leaf fall, it makes sense to clear the lawn of leaves.
Interesting observation
The calendar shows the end of November, during the day the temperature stays between -4-6 ⁰C, and at night drops to -12 ⁰C, and the young apple tree, in violation of all the laws of nature, has not yet shed its leaves. And a neighboring apple tree of the same age dropped them.
And here is another eloquent example: the maple has completely dropped its leaves, and on the poplar growing nearby, although they have turned yellow, they are still holding on.
Walking around the neighborhood, I noticed two neighboring birch trees: one stands bare, and the other is still in foliage.
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