Apple trees (Malus x domestica) are one of the most popular fruit trees grown in the world today. There are thousands of cultivars of this popular fruit tree. Methods of propagation of the apple are numerous and can vary widely. Some of the most popular methods of propagation are grafting and budding. Air Layering is also done for apple rootstocks.

Most apple production today is from clonally propagated fruiting varieties, which include Anna, Crispin and Red Delicious, Pink Lady, which are grafted and budded onto clonal rootstocks. These rootstocks are specially selected to affect the size and disease resistance of the tree.

Apple Tree Propagation

Like most fruit trees, contemporary cultivation methods suggest that apples are ordinarily propagated asexually by grafting.

Because the seeds (sexual propagation) produced by apple fruits are the result of cross-pollination, the resulting seedlings are not genetically identical to each other or to the “mother” tree.

To create multiple copies of the same cultivar, asexual (i.e., not sexual) — also called vegetative — propagation techniques are required, and apples are easily budded and grafted.

In the wild, apples grow from seeds. Seedling apples are an example of “extreme heterozygotes”. Rather than inheriting DNA from their parents to create a new apple with those characteristics, they are instead significantly different from their parents. This means that if we plant the seeds from 10 apples of exactly the same variety, all 10 apple trees that will be created will be significantly different and will give accordingly different fruits.

Consequently, professional farmers choose grafted apple seedlings, in order to achieve product uniformity and quality. In a few words, professional apple growers benefit from an apple tree that is a combination of two different plant tissues, the rootstock and the scion. The rootstock is the lower part of the tree and produces the root system. Rootstock also determines the tree’s final height.

The scion produces the upper part of the tree and of course determines fruit’s characteristics. Both the rootstock and the scion must be carefully selected and each one of them may result in poor production.

Grafting

Grafting involves joining two pieces of genetically different living plant tissue together so they grow together as one plant. The lower part of the compound plant is known as the stock or rootstock. This is the part that produces the root system.

The upper part is referred to as the scion and produces the shoot system of the plant.

For grafting, a short piece of the tree of a desired variety is taken and placed onto a limb of the rootstock. Grafting is usually done during the dormant season and must be done on dormant scion and stock wood. There are many methods of grafting, but the main objective is to unite the cambium layers from the scion and the stock together so the plant grows as one.

Whip-and-Tongue Graft

The whip-and-tongue graft is usually done on small diameter material (6-13mm) and is one of the strongest types of grafts. High success rates are seen with this graft because the cambium layers have a lot of surface contact.

When selecting material for this graft, it is important to have the scion and stock of somewhat equal diameter. A section of scion with two or three buds should be used. Identical cuts are made at the top of the rootstock and bottom of the scion, so the two pieces fit together nicely. The first cut is about 1-2.5 inches long and made at an angle with one long and continuous motion of the knife. This first cut should be made on the scion in the internode area below the two or three buds. Smooth cuts are essential so that good cambium layer contact will occur.

An identical cut is then made on the rootstock. A second cut is started about a third of the way down from the tip of the first cut. This second cut should be about half as long as the first cut and made parallel to the first.

After this second cut is made on both the scion and stock, the two pieces are interlocked. They should fit together perfectly, with no gaps.

At this point, it is very important that the vascular cambium layers come into contact on one or both sides of the cuts. The tips of the cuts should also not overlap the material they are grafted onto to avoid callus knots. The graft can be held together by budding rubber strips or grafting tape. To keep the moisture in the tissues, sealing the graft with grafters wax or Parafilm is sometimes done. The grafts can also be placed in very high relative humidity until the graft begins to take.

Whip Grafting

Whip grafts are very similar to whip-and-tongue grafts.

The only difference is that the second cut is not made when doing the whip grafts. The first cut is again identical to the whip-and-tongue cut (smooth, sloping and 1-2.5 inches long).

The cut is made on both the scion and stock and the two pieces are fitted together, making sure good cambium contact occurs.

The graft is wrapped as described above. It is common for this type of graft to be done on apple tree material with specialized machines.

Budding

Budding is a form of grafting in which only a bud and a small piece of bark from a stock is used.

For budding to be done, the bark on the rootstock must be slipping, meaning the bark can be easily separated from the wood. When the bark is slipping, the plant is actively growing and the cambium cells are dividing.

T-Budding

T-budding is usually done on rootstocks that range from 6 to 25 mm in diameter.

The first cut on the rootstock is a vertical cut through the cambium and just into the wood tissue, about 5 to 25 cm above the soil level. Then a horizontal cut just above the vertical cut is made to form a T in the bark. The knife is twisted when this horizontal cut is made to slightly open up the T so the flaps formed can be peeled back.

Removing a bud on the scion is done by making an upward slicing cut about 13 mm below the bud and then cutting upward to about 2.5 cm above the bud. The bud is removed then by a horizontal cut about 1.3 to 1.9 cm above the bud. This bud shield is then inserted into the T-shaped cut flaps and slid under the bark flaps until the top edges are even.

The bud union area is then wrapped with budding rubbers or wrapping tape, being careful not to cover the actual bud itself. It is important to not tie the tape or budding rubbers too tight or too loose. The top part of the seedling rootstock is removed after growth from the bud occurs

Chip Budding

Chip budding is done on 13 to 25 mm in diameter material.

For this type of budding, a small chip of bark is cut out from the rootstock near the base and an identical size and shape chip from the scion is put back in its place. Identical procedures for cuts are used for both the scion bud removing and the rootstock chip removing. A 30-45 degree angle is cut below the bud and into the wood about ¼ of the way. Then another cut is made about 1 inch above the bud and sloping downward, cutting behind the bud. This cut is made all the way down until it reaches the first cut, thereby completely removing the bud chip from the scion.

As stated previously, identical cuts are made on the rootstock. So the chip from the scion can then be inserted onto the area of the rootstock where the chip was removed. Again, care must be taken to insure the cambium layers from the rootstock and the scion chip are meeting in the graft area.

Contact is better if the cambium layers meet on both sides, but contact on only one side is really needed. Wrapping the chip bud with nursery adhesive tape or transparent plastic tape holds the two pieces together firmly and keeps the moisture in the bud area. The tape is cut when the bud start to grow and the top of the rootstock is removed when the graft has taken, meaning the union is complete.

Mound Layering

Mound layering is used to propagate apple clonal rootstocks. In this method, soil is mounded around shoots that have been cut back, thereby stimulating roots to grow at the base of the shoots.

A year before propagation begins, eight to ten millimeter diameter stock plants are planted in rows and then cut back to 45-60 cm. They are then grown for one year. The plants are again cut back, this time to 2.5 cm above the ground. New shoots gradually form and more soil and bark is added in mounds around the plants. This cycle may continue on through the growing season.

Then the shoots are harvested by cutting close to the bases. The mother stool beds are then left exposed until further growth of the new shoots has occurred and another cycle of hilling begins

Rootstocks

When propagating apple trees, a great deal of attention is put on the roots, probably more than any other species. Rootstocks are used for grafting and propagation of apple scion varieties.

In Kenya, as well as in many other regions around the world, apple trees are commonly propagated using rootstocks. Rootstocks are specific varieties of apple trees that are used as the root systems onto which the desired apple cultivar, known as the scion, is grafted. The choice of rootstock depends on various factors such as soil conditions, climate, disease resistance, and desired tree size.

Here are a few examples of apple rootstocks that have been widely used:

1. Malling series: The Malling series of rootstocks, such as M.9, M.26, and M.7, are among the most popular and widely used in many apple-growing regions. M.9 is a dwarfing rootstock, resulting in small-sized trees suitable for high-density orchards and easy maintenance. M.26 is semi-dwarfing, providing moderate tree size and good anchorage. M.7 is more vigorous, suitable for free-standing trees or in areas with heavy soils.
2. Geneva series: The Geneva series, including Geneva 11, Geneva 41, and Geneva 890, were developed at the Cornell University Agricultural Experiment Station. These rootstocks are known for their resistance to fire blight and are suitable for regions where this bacterial disease is a concern. They have varying growth habits and adaptability to different soil types.
3. MM.111: This rootstock is known for its vigorous growth and adaptability to a wide range of soil types. It produces large-sized trees, making it suitable for traditional orchards or where larger trees are desired. It is more resistant to adverse soil conditions, such as heavy or wet soils, compared to some other rootstocks.
4. Budagovsky (Bud) series: Budagovsky 9 (B.9) and Budagovsky 118 (B.118) are examples of rootstocks developed in Russia. B.9 is a dwarfing rootstock suitable for high-density plantings, and B.118 is more vigorous and provides good anchorage. These rootstocks are known for their cold hardiness and are used in colder climates.

About M9 Rootstock Commonly Used In Kenya

M.9 rootstock, also known as Malling 9, is a dwarfing rootstock widely used in apple orchards around the world. It was developed in the mid-20th century at the East Malling Research Station in the United Kingdom. Here are some key characteristics and information about M.9 rootstock:

• Dwarfing Characteristics: M.9 is highly regarded for its dwarfing effect on the scion, resulting in smaller trees compared to standard-sized apple trees. The reduced tree size offers several advantages, including easier tree management, increased planting density, and improved fruit quality.
• Tree Size and Vigor: M.9 rootstock typically produces trees that are 40-50% of the size of a standard seedling rootstock. It has a moderate to low vigor, meaning that the trees are smaller and have a less extensive root system. This makes them suitable for high-density orchards and areas where space is limited.
• Early Bearing: One of the notable characteristics of M.9 rootstock is its ability to induce early fruiting. Apple trees on M.9 tend to bear fruit at a younger age compared to larger rootstocks. This early bearing can be advantageous for commercial growers looking to achieve earlier returns on their orchard investments.
• Adaptability: M.9 rootstock is adaptable to a wide range of soil types and climates. It performs well in various regions but is particularly suited to well-drained soils. However, it may require additional irrigation in dry areas due to its smaller root system.
• Support Requirements: Due to its dwarfing nature, M.9 rootstock requires proper support systems to maintain tree stability. Trellising or staking methods are commonly employed to provide adequate support to the trees, especially when they bear a heavy fruit load.
• Disease Susceptibility: M.9 rootstock is moderately susceptible to fire blight, a bacterial disease that affects apple trees. While it may not have the same level of disease resistance as some other rootstocks, it is still widely used and can be managed through appropriate cultural practices and disease control measures.

It’s important to note that M.9 rootstock has several different clones within the M.9 series, such as M.9 T337 and M.9 Pajam 2. These clones may exhibit slight variations in growth habit, disease resistance, and adaptability.

Apple Tree Pollination

Most of apple tree varieties are not self-fertile. This means that most apple trees need pollination partner trees of a different variety in order to set fruit. Even the self-fertile apple varieties are reported to produce higher yields when a pollination partner tree is planted at a close distance. The various commercial apple cultivars flower at different times, starting with Granny Smith and ending with Red Delicious.

Apple farmers must plant pollinating cultivars that are compatible and flower at closely the same time as the commercial cultivars. It is also important to place the pollinating cultivars at different spots of the orchard, so as to ensure adequate cross pollination.

Apple trees need bees at a great percentage in order to pollinate and produce fruits. In commercial apple farms, placing 3 beehives every 2,5 acres (or 1 hectare) of orchard has been found to be beneficial, if not necessary.

FOR GRAFTED APPLE SEEDLINGS, CONTACT +254 724559286

Apple Tree Soil requirements and step by step on Preparation

Apple trees have specific soil requirements to thrive and produce high-quality fruit. Here are the general soil requirements for apple trees and a step-by-step guide for soil preparation:

Soil Requirements for Apple Trees:

• Well-Drained Soil: Apple trees prefer well-drained soil to prevent waterlogging, as excessive moisture can lead to root rot and other diseases. Avoid heavy clay soils that retain water.
• pH Level: The optimal soil pH for apple trees ranges from 6.0 to 7.0. Conduct a soil test to determine the pH of your soil. If the pH is outside the ideal range, you may need to amend the soil to adjust it.
• Organic Matter: Apple trees benefit from soil rich in organic matter. Organic matter improves soil structure, enhances water retention, and provides nutrients. Compost or well-rotted manure can be incorporated into the soil to increase organic matter content.
• Nutrient Content: Apple trees require essential nutrients like nitrogen, phosphorus, and potassium, along with micronutrients. Conduct a soil test to assess the nutrient levels and make necessary amendments based on the test results.

Step-by-Step Soil Preparation for Apple Trees:

• Site Selection: Choose a location that receives full sunlight for at least six to eight hours a day. Avoid areas prone to frost pockets or strong winds. Ensure adequate space between trees for proper air circulation.
• Clear the Area: Remove any grass, weeds, or existing vegetation from the planting area. This will minimize competition for nutrients and water.
• Digging the Hole: Dig a hole that is wide and deep enough to accommodate the apple tree’s root system comfortably. The hole should be wider than the spread-out roots and deep enough to accommodate the entire root ball without bending or crowding the roots.
• Soil Amendment: If the soil pH is outside the desired range, you can amend it by incorporating suitable materials. For example, to raise pH, you can add agricultural lime, and to lower pH, you can use elemental sulfur. Follow the recommendations based on your soil test results.
• Organic Matter Incorporation: Mix compost or well-rotted manure into the soil removed from the planting hole. This will help improve soil structure and fertility. Aim to incorporate approximately 1/3 to 1/2 of organic matter into the backfill soil.
• Planting the Tree: Place the apple tree in the center of the hole, ensuring that the graft union (the swollen area where the scion and rootstock meet) is above the soil line when backfilled. Spread out the roots and gently fill the hole with the amended soil mixture. Avoid compacting the soil too tightly around the roots.
• Watering and Mulching: After planting, thoroughly water the tree to settle the soil and eliminate air pockets around the roots. Apply a layer of organic mulch, such as wood chips or straw, around the base of the tree to conserve moisture, suppress weeds, and regulate soil temperature.

Remember to provide regular irrigation, adequate nutrition, and monitor for any signs of pests or diseases. Pruning and training the apple tree as it grows will also be essential for its overall health and productivity.

Apple Tree Planting Distances and Population – Number of Apple Trees per Acre

We start by digging a hole of 25 inches (63cm) diameter and 25 inches (63cm) depth for every young apple tree that we intend to plant. We then place the trees carefully inside the holes and we cover with soil. Keep in mind that the point where the scion is attached must be at least 3 inches (7,5 cm) above the ground level.

Adding a fertilizer at that time will most probably hurt the young roots of the trees, so it must be avoided. We can irrigate and start pruning the young trees (in order to give them shape) immediately after planting.

The distance that we leave between the apple trees depends on the apple cultivar, and more specifically on the final size of the mature tree and our preference regarding extensive farming.

The distances between rows and between trees in the row range from 22 X 16 feet to 6 X 6 feet (7m X 5m to 1,8m X 1,8 m). 22 X 16 feet pattern results in 124 trees per acre, or 310 trees per hectare.

6 X 6 feet pattern results in 1210 trees per acre, or 3000 trees per hectare, and of course can be achieved only by using dwarf varieties.

In the previous years, apple trees were spaced at an average of 20 X 20 feet (6 m x 6 m). This pattern gave 109 trees per acre or 250 trees per hectare and took about 20 years to reach maximum production. However, nowadays -by using dwarf rootstocks – we can have about 2000 trees per hectare or 800 per acre and maximum production can be reached within 6-7 years.

How to water apple trees

The average young apple tree needs a lot of water in order to develop strong roots, leaves and finally fruits. As a rule of thumb, young apple trees need more water than mature apple trees, which can rely mostly on rainwater in regions with frequent rainfalls.

As a second rule of thumb, in regions where there are no frequent rainfalls, it is beneficial to irrigate apple trees (especially the younger ones) about once a week. Every field is different and has different needs. Although some general rules may apply, soil texture and climate conditions determine at a great percentage the amount of water needed in order to harvest a fair yield.

Kitchen garden apple growers often built a circular soil wall 3-5 feet (1-1,5 m) around the apple trunk and add a thin layer of mulch in it, so as to increase the rainwater holding capacity of the soil.

Apple Tree Fertilizer Requirements

Nitrogen and Potassium are very important for leaf growth, flowering and fruit set, while Phosphorus is crucial for the development of a strong root system especially at the early stages of plant development. Calcium, Magnesium, Manganese, Zinc and Boron are also important for various stages of bud development, flowering and fruition and any deficiency will have a negative effect in fruit number, quality and general tree health.

As a rule of thumb, mature fruit bearing trees need more fertilization than young trees that have not entered their fruition period. The average mature apple tree needs 0,6 lbs. (270g) of N per year, while the average young non-bearing fruit needs only 0,15 lbs. (68g) of N per year. These are the rates for standard height trees, so the needs of dwarf trees are normally decreased by 40%.

A common fertilization scheme used by many apple growers is adding once a year 1- 4 lbs. (0,5-2 kg) N-P-K 12-12-12 or 11-15-15 per young tree and 3-5 kg N-P-K 12-12-12 or 11-15-15 per mature tree.

Keep in mind that 1 ton = 1000 kg = 2.200 lbs. and 1 hectare = 2,47 acres = 10.000 square meters.

Most soil fertilizers are applied from March to July. Especially if there is a Phosphorus deficiency, we may have to apply N-P-K 0-25-0. Keep in mind that the 0-25-0 fertilizer must not come in contact with the tree roots. A second commonly used fertilization scheme in an average commercial apple orchard with 600 mature trees per hectare is adding 110 kg N and 200 kg K₂0 per hectare, whereas Phosphorus, Magnesium and Calcium fertilizers are added according to leaf analysis.

However, these are just common patterns that should not be followed without making your own research. Every field is different and has different needs. Checking the soil nutrients and pH is vital before applying any fertilization method.

Moreover, if a full coverage irrigation system is combined with the presence of Alfalfa or other legumes (as a cover crop) in a dense planting system, the need for fertilizing apple trees is remarkably reduced, because the cover crop normally produces organic matter that is decomposed, releasing important nutrients to the soil.

The normal levels of the most important nutrient are listed below:

N: 2% – 2,4%

P: 0,1% – 0,3%

K: 1,1% and above

Ca: 1% and above

Mg: 0,25% and above

Harvesting Apples – Apple Tree Yield

Harvesting apples is an exciting time for apple growers as they reap the rewards of their efforts. The yield of apple trees can vary depending on various factors such as apple variety, tree age, orchard management practices, climate conditions, and disease and pest control measures. Here is some general information about apple tree yield and harvesting:

Apple Tree Yield:

The yield of apple trees is typically measured in terms of the number of fruit produced per tree or the weight of fruit harvested.

The yield of apple trees can be measured in terms of kilograms (kgs) of fruit harvested. However, it’s important to note that the actual yield can vary significantly depending on various factors, as mentioned earlier.

On average, mature apple trees can produce anywhere from 20 to 200 kgs of fruit per tree per year, depending on the variety and growing conditions. Some high-yielding apple varieties can produce even higher yields, exceeding 200 kgs per tree. However, these numbers are approximate and can vary based on factors such as tree age, orchard management practices, and environmental conditions.

Young apple trees typically have lower yields compared to mature trees. It takes a few years for apple trees to reach full productivity. Generally, apple trees start bearing fruit in their second year, with yields gradually increasing as the trees mature.

Harvesting Apples

Apples are typically harvested when they reach the desired maturity for the specific apple variety. Harvest timing varies based on the variety and the intended use of the apples (fresh consumption, storage, or processing). It’s important to follow the recommended harvest guidelines for each variety to ensure optimal flavor, texture, and storage life.

Apples are usually hand-picked from the tree to avoid bruising or damaging the fruit. The harvesting process involves carefully twisting or gently lifting the apple to detach it from the spur or branch. It is advisable to handle the fruit with care during harvesting to minimize any potential damage.

Apple Tree Pests & Diseases

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