Korobovka apple tree: characteristics of the variety and care

Description of the Korobovka apple variety

This ancient Russian apple variety, a folk selection, has not been grown commercially for many years. The main reason for its abandonment is that its fruits, compared to new, promising varieties, are very small. However, at fruit farms across Russia, Korobovka is still used as the mother tree for winter-hardy, early-ripening apple trees.

Apples: What they look like

The fruits are predominantly small to very small. They rarely reach 35-50 grams in weight, with a diameter of no more than 4-6 centimeters. They are round, often unevenly sided, flattened or flattened, and nonuniform. The ribbing is subtle and barely noticeable to the naked eye.

The fruit skin is dense, smooth, and glossy, often with a distinct oily coating. It is dirty green or slightly yellowish when ripe. It has a faded red-orange blush, blurred, streaked, and spotted. Subcutaneous punctures are light, numerous, light gray or slightly greenish, and clearly visible on the surface. The chemical composition is characterized by the following indicators per 100 grams:

• P-active substances (catechins) – 223 milligrams.
• Ascorbic acid (vitamin C) – 7 milligrams.
• Total sugars (fructose) – 19.8%.
• Pectins (fiber) – 11.2%.
• Titratable acids – 0.68%.

The flesh is dense, fine-grained, juicy, and crisp, with a distinct dirty-yellow hue. It is predominantly sweet, with almost no characteristic sourness, and has a distinct honey flavor. It has a pleasant, dessert-like, and harmonious taste. While the fruit has not been given a tasting score, experts note that all lovers of sweet apples rate them highly.

Apple tree Korobovka: characteristics

Crown and root system

The tree is considered tall because, without any shaping, it can reach 6-7 meters or more in height, especially in warm climates. However, in northern regions, it grows no more than 5-6 meters, which is still quite tall when it comes to ease of harvesting. In its early years, the crown of the Korobovka has a distinct pyramidal shape, narrowing toward the top and widening toward the lower skeletal lids. However, over the years, it becomes broadly oval, and sometimes even spreading and weeping.

The medium-length, strong shoots extend from the trunk at an acute angle and are covered with dark brown or brown, smooth, glossy bark that tends to crack and crumble with age. The leaves are small, densely covering the branches, rounded but slightly elongated, short-pointed, matte, usually green or light green, but can even be emerald. The root system is extensive, deeply rooted, and well adapted to seeking water.

Productivity and pollination

This variety has an average yield, typical of old, traditionally bred trees. It's one of those types that is increasingly gaining popularity over time.

A mature tree typically yields approximately 40-60 kilograms of delicious, honey-scented fruit during the initial stages of full fruiting. However, the tree doesn't reach its peak until it's 15-20 years old, when it can harvest 65-80 kilograms of fruit..

This variety is considered self-sterile, so without the help of other apple varieties whose flowering periods overlap, no fruit will be produced. It's best to plant trees of different varieties close together to allow bees and wind to pollinate them. Spraying the branches and flowers with diluted sugar syrup and bringing mobile apiaries to the planting sites is recommended.

Winter hardiness and disease resistance

Its high tolerance to low temperatures and sudden temperature fluctuations has made this variety popular, despite its more than two-hundred-year history. Apple trees are virtually immune to frosts down to -35-37°C, and even after lower temperatures, no significant damage to the ovaries is observed. They bear fruit at almost the same rate as usual. If winter preparation is carried out promptly and correctly, then there is no need to worry about more severe weather conditions.

Old apple trees usually have moderate resistance to infectious fungal diseases, and Korobovka is one of them. It can be affected scab and powdery mildew, black crayfish and cytosporosis, which attacks quickly and abundantly. The tree is also susceptible to insect pests, and the codling moth simply adores tender, sweet fruits. Therefore, all insecticide and fungicide spraying should be done at the appropriate time.

Rootstocks and subspecies

The tree is most often grown on standard seedling rootstock, but it can also be grafted onto semi-dwarf and dwarf varieties. The tree's basic characteristics, other than height, remain largely unchanged. The subspecies and subvarieties of Korobovka are unknown to science.

Features of growing Korobovka

Landing

Basic conditions

• For this variety, choose open, sunny, and wind-blown spaces, but avoid drafts. No fruit tree will tolerate this, so choose carefully.
• Groundwater levels should be at least 2-3 meters below the surface, otherwise the trees will reach it with their extensive rhizomes and rot. This will lead to the death of the trunk. For the same reason, Korobovka should not be planted near rivers or lakes, ponds, or wells.
• Leave at least 4-5 meters between trees in a row, and about the same distance between rows, to prevent them from obstructing each other in the future. Keep in mind that the crown will become more spreading and take up more space over the years.
• You can plant the variety in pre-dug holes dug in the fall using the traditional method, or you can make new ones in just 2-3 weeks. They should be 60-80 centimeters deep and up to 1 meter in diameter. Add some soil to the bottom. soil with fertilizers, gravel or other drainage is placed on top, and then all this is watered with water (35-40 liters).
• It's a good idea to insert a stake (wood, plastic, or metal) into the holes immediately for staking. Ideally, it should be positioned north of the tree trunk. These stakes should not be removed until 4-5 years after planting in open ground.
• It's customary to leave the root collar 10-12 centimeters above ground to prevent trees from rooting higher. This completely negates all the rootstock's properties.
• Place the seedling vertically in the holes, cover with soil layer by layer, and compact it by hand, being careful not to compact the soil to a granite-like consistency. Water with 25-40 liters of water, and mulch the surface with sawdust, chopped grass, compost, or manure to prevent rapid evaporation.

Landing dates

The Korobovka apple tree is a very hardy and undemanding tree, so planting timing isn't particularly critical. It can be planted either in early spring, as soon as the soil thaws and the potential for frost has passed, or in the fall, when all the leaves have fallen from the trees and the frost is still at least 2-4 weeks away. Seedlings that closed root system, can be moved to open ground at any time from spring to autumn.

Protection from frost and rodents

Many people think that because a tree is frost-hardy, no preparation for the cold season is necessary, but this is a misconception. Trees still need to be protected and covered, especially when the winter promises to be frosty. Trunks are wrapped in burlap, roofing felt, or agrofibre, and mats of dry grass or straw are placed around the roots. Only very young trees can be covered using a tent-like method, as they will grow excessively tall later.

To get rid of insect pests that happily overwinter in bark crevices or at the roots, trees are treated twice a year with lime (whitewash) to a depth of at least 1-1.3 meters. To repel rodents in winter, which eat not only the bark but also young shoots, it's a good idea to coat the trunks with lard or grease.

Tree care

Loosening the soil, watering: proper agricultural technology

Loosening the soil is beneficial for the growth of any fruit, and not just trees. Therefore, once or twice a year, you can dig up the area around the tree's trunk. The rest of the year, you can lightly hoe the soil, preventing it from compacting. Don't forget to remove root suckers, which can be quite abundant, as well as weeds and other plants. Around the 15th to 17th year, you can cover the area around the tree's trunk with pieces of sod to make the work easier.

Korobovka doesn't require much regular watering; it does an excellent job of extracting moisture from the soil itself. However, if the weather is excessively hot and very dry, you can water the tree approximately 4-6 times per season. It's a good idea to time watering to coincide with bud formation and fruit ripening.

Pruning: simple crown shaping

Standard pruning is performed starting two to three years after planting in open ground, especially if the tree came from a nursery rather than home-grown. The main stem is shortened by no more than a third, and all skeletal branches are shortened even further. It's best to leave no more than three or four branches, at different heights and widely spaced.

Don't forget about sanitary pruning, which is usually performed in late fall or early spring. This involves removing all diseased, damaged, or dead shoots, and sealing the cut areas with garden pitch or any other suitable material.

Ripening and fruiting of Korobovka

The beginning of fruiting

Korobovka doesn't begin bearing fruit early, only 7-9 years after planting. However, it produces quite a lot of fruit right away, up to half of the future harvest. At this point, you can harvest at least 25-40 kilograms of small but delicious fruit from relatively young trees.

Flowering time

This variety begins to bloom in May, like most other apple trees. However, the flowering process can fluctuate depending on the climate, other growing region factors, and even the weather. In cool, rainy winters, trees may not bloom until mid- to late-May. The flowers themselves are small, numerous, and very fragrant, densely covering the branches. They look especially beautiful on older trees, whose vines sometimes droop low to the ground, becoming spreading.

Fruiting and growth

Trees of this variety grow slowly, no more than 15-25 centimeters per year, but only after they begin bearing fruit. Before then, they quite vigorously reach 2-3 meters, adding at least 40-50 centimeters per season. Fruitfulness also increases exponentially, reaching its maximum within just a couple of years. Korobovka actively bears fruit for 25-40 years, after which it may undergo periods of rest, which can last for 2-4 years.

It's common to pick the fruit as early as early July, as they ripen by the end of June. In mid-June, they begin to ripen gradually, starting from the upper branches and moving down, and in July, this process begins en masse. The fruit holds firmly to the branches and almost never falls off on its own, unless you delay harvesting until September or October or the trunks are damaged by pests. Apples have a poor shelf life; they'll likely last barely 20-30 days, so it's best to process them immediately.

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