Apple tree not shedding leaves in autumn: reasons and what to do

Plants prepare for winter in different ways: deciduous trees shed their leaves in the fall, while indoor perennials and evergreens in warmer regions enter a dormant period. If a fruit tree, including an apple tree, doesn't shed its leaves for the winter, there's a reason for this, and steps must be taken to correct the situation and prevent the tree from dying in subzero temperatures.

Leaf fall – what is it for?

All processes occurring in plants are interconnected, and each can be scientifically explained. The fall leaf shedding is a mechanism developed by nature through evolution, helping to cope with the changes that occur with the changing seasons and preserve vitality.

A tree's green mass occupies a certain area, from which moisture is constantly evaporated, which is easily replenished during the warmer months. When temperatures drop, sap flow slows, making it more difficult to extract water from the soil. In winter, it's impossible to extract water from the frozen ground, so leaves begin to fall in the fall, protecting the plant from excessive moisture loss. The same phenomenon occurs in areas with drought in winter—trees remain leafless until the rainy season arrives.

With the onset of autumn, light decreases due to shorter daylight hours, and water consumption declines, which contributes to the breakdown of chlorophyll and leaf coloration, turning yellow. Nutrients are "stored" in the roots and trunk, and the plant is ready to shed its leaves. At the same time, corky tissue forms in the petiole, which breaks in the wind, and leaf fall begins. This, by exposing the branches, protects the crown from the weight of snowfall. If the leaves haven't fallen yet, the branch's mass increases significantly, and it can break off under the weight of snow. For fruit trees with spreading crowns, this situation is especially dangerous, as lateral branches are more likely to break off.

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Why hasn't the apple tree shed its leaves and what should I do?
The timing of apple tree leaf fall can vary among different cultivars. Late-ripening varieties tend to have shoots that remain green longer because they dedicate their nutrition to the fruit until almost mid-autumn.

 

Another reason for leaf shedding is protection from excess salts. During the summer, leaves accumulate a large amount of mineral salts, absorbed with water. Some of these are used for nutrition, while others remain and accumulate in leaf tissue. Therefore, using the ash of fallen leaves as fertilizer is not recommended. By shedding leaves, the plant rids itself of excess minerals, which, if present, can disrupt the processes occurring in plant tissue.

The apple tree hasn't shed its leaves – possible causes and consequences

Leaves that turn yellow at the right time indicate that the growth process has ended, the bark on young shoots has matured, and the tree is ready for winter. If the apple tree's leaves haven't fallen, there's a reason, and it needs to be identified to begin treatment.

Remaining foliage on a fruit tree is not normal for most varieties, and should not occur with proper care and adherence to agricultural practices. Leaf shedding is not a one-time process, and the timing varies for different varieties. For example, in the Antonovka variegated fruit tree, the leaves remain on the branches until spring. However, if in late autumn the leaf is green, firmly attached to the branch, and the shoots are weakened and grassy, ​​this indicates problems in the tree's tissues.

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Possible reasons:

• nitrogen fertilizers applied in July or August, organic fertilizing in the fall cause a delayed growth of green mass;
• non-compliance with agricultural technology during planting - the hole is too deep, more fertilizer than necessary was added to it;
• Summer pruning, if done incorrectly, can provoke late growth of shoots;
• a large amount of moisture due to a rainy summer, frequent and abundant watering delays the onset of dormancy;
• drought in early summer will cause growth to slow down or stop, while rains that begin after a long period of drought will cause shoots to grow;
• the apple tree variety does not correspond to the climatic conditions of the region - late-ripening varieties intended for cultivation in warm regions do not have time to ripen in mid-latitudes;
• the temperature drop occurs earlier than the climatic periods - early frosts kill leaf tissue, the cells stop working, so the leaves remain green and do not fall off (a similar situation is observed with fruits);
• too warm September slows down the process of preparation for winter, so the leaves do not fall for a long time;
• Infectious diseases lead to disruption of all processes, which affects the timing of leaf fall.

November hasn't started yet – how to fix the situation

If the leaves do not start falling at the usual time, and in autumn the apple tree stands with leaves, This means it's not ready for winter. By thoroughly analyzing all the work done on the apple tree plantings, you can determine the cause of the delay and avoid making the same mistakes next year.

What to do:

• Observe the planting dates for the seedling, taking into account the local climate - the young tree must take root well and become strong before the onset of cold weather;
• choose regionalized varieties adapted to the local climate;
• Use nitrogen fertilizers only in spring, and apply phosphorus-potassium mixtures in the second half of summer and autumn;
• Before the onset of autumn frosts, whitewash the trunk and skeletal branches to reduce the risk of damage by parasitic insects;
• pour a 10 cm layer of mulch in the trunk circle when the time of frost comes (fallen leaves cannot be used - they contain pathogens and pest larvae), 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 low trees that still have leaves, and wrap up the seedlings completely.

All work is carried out in advance to prevent the apple tree from losing its leaves in the fall. To force the tree to shed its leaves before winter sets in, special preparations are used.

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Leaf shedding products

Consider using treatments as early as September, when the crown is green and there are no yellowed leaves, shoots have not become woody, and bud differentiation has not occurred (inflorescence primordia have not formed). There are special treatments called defoliants, based on synthetic inhibitors, that cause leaf drop. They should not be used preventatively; their use must be justified by necessity.

It is not recommended to use outdated, highly toxic products, as they can cause dangerous side effects, such as marginal burns and damage to growth points. These include etafon, etrel, desitrel, and others. Magnesium chlorate and sodium chlorate are the least toxic.

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Defoliants work by accelerating the aging process and destroying chlorophyll when they penetrate leaf tissue. This treatment should cause the leaves to fall off. To achieve maximum effectiveness, treatment should be applied at the very beginning of the natural aging process; early application reduces its effectiveness.

Mistakes made by gardeners

Sometimes, to speed up leaf fall, people resort to actions that can harm the tree and affect its development in the following season. If the situation is noticed late, the snow is already on the ground, and the apple trees haven't lost their leaves, then nothing needs to be done. The only thing that can help is to build a snow shelter and wrap the young tree with additional covering material.

What you shouldn't do:

• to tear off, to cut off leaves - tearing off damages the bark at the point where the petiole is attached;
• Use high-concentration herbicides – the tree gets severely burned and suffers stress, which ultimately reduces its resistance to frost.

If an apple tree hasn't shed its leaves in the fall, it's a sign that the tree isn't ready for winter. Before the cold weather sets in, you need to take steps to preserve the buds and shoots by analyzing the underlying causes.