Harvesting and storing

Signs of Harvest Maturity

The approach of harvest maturity can be determined by a combination of external and internal signs:

1. Change in the ground color of the fruit. During ripening, the green background of the skin gradually changes to yellow or yellowish-white. This change in the ground color is more reliable than the appearance of a red blush, which strongly depends on illumination and weather conditions (Westwood, 1993).

2. Seed color. In fruits that have reached harvest maturity, the seeds acquire a brown color. The scale for assessment is as follows: 1 point – seeds are not colored; 2 points – browning of the seed tips; 3 points – half of the seed is colored (which corresponds to harvest maturity); 4 points – three-quarters of the seed is colored; 5 points – seeds are completely brown (Tarasov et al., 1981).

3. Stem separation. During ripening, an abscission layer forms between the stem and the fruit spur. If you lift the apple and slightly twist it, the stem easily separates from the branch without jerking or breaking. This is one of the most reliable practical signs (Phillips, 2005; Tarasov et al., 1981).

4. Starch-iodine test. This is the most objective method available to every gardener. The starch accumulated in the fruits is converted into sugars during ripening, so its content serves as an accurate indicator of the degree of maturity. For the test, several typical fruits are cut in half, and the cut surface is dipped in an iodine solution (3 g of potassium iodide and 1 g of crystalline iodine per 100 ml of water). After 1–2 minutes, the degree of staining of the cut surface is assessed (Tarasov et al., 1981).

Starch-iodine test scale:

• 5 points – the entire cut surface is stained dark (fruit is unripe).
• 4 points – only small areas (near the stem and seed cavities) remain unstained; ripening has begun.
• 3 points – the cut surface is weakly stained up to 50% of the area. This is the optimal degree for laying down winter varieties for long-term storage.
• 2 points – only the areas under the skin are stained.
• 1 point – weak staining only under the skin (less than 50% of the fruit's circumference), which corresponds to consumer maturity (Tarasov et al., 1981).

Characteristics of Different Variety Groups

Different apple varieties have their own timing for reaching harvest maturity, and this must be taken into account when planning the harvest.

• Summer varieties (Grushovka Moskovskaya, Papirivka, Belyi Naliv). In these varieties, harvest and consumer maturity occur almost simultaneously. They are picked 5–7 days before full ripeness, when the fruits have already filled out but are still firm enough for short-term transportation. Consumer maturity occurs 60–95 days after the end of flowering (Tarasov et al., 1981). Summer apples do not store for long – from a few days to 2–3 weeks.

• Autumn varieties (Korichnoe Polosatoe, Borovinka, Osennie Polosatoe). These apples are picked when the starch level is 2–3 points on the iodine test. They reach consumer maturity 2–3 weeks after picking. The period from the end of flowering to harvest maturity is 95–115 days. Under appropriate conditions, they store for 1–3 months (Westwood, 1993; Tarasov et al., 1981).

• Winter varieties (Antonovka Obyknovennaya, Severnyi Sinap, Renet Simirenko, Jonathan, Golden Delicious). For long-term storage, they are harvested when the starch content is 3–4 points (up to 50% staining of the cut surface). The period from flowering to harvest maturity is 116–135 days or more (Tarasov et al., 1981). Only picked in the optimal phase, such fruits can be stored for 4–8 months or more, gradually acquiring their full flavor and aroma.

It is important to remember that apples intended for long-term storage must be picked underripe but already at harvest maturity. Overripe fruits do not store well, while too-green ones do not develop the proper quality and shrivel (Agustí, 2010; Phillips, 2005).

Influence of Weather Conditions on Ripening Dates

Weather conditions during the growing season can significantly shift the timing of harvest maturity. The main factor is the sum of effective temperatures, i.e., the heat the trees received from flowering to harvest.

• Warm weather in the post-flowering period accelerates ripening. For Bartlett pear, for example, it has been established that the more heat units (sum of effective temperatures) accumulate in the first 36 days after full bloom, the earlier harvest maturity occurs (Westwood, 1993). A similar pattern is characteristic of apple trees.

• Cool weather slows down ripening and delays the harvest date. In rainy and cold years, the harvest of winter varieties is often carried out 5–7 days later than the average dates (Tarasov et al., 1981).

• Weather fluctuations from year to year are an important reason why one cannot rely solely on calendar dates. For instance, for one variety in the same region, the difference between the earliest and latest harvest dates can reach 15–20 days. Therefore, relying on calendar dates without checking the signs of maturity is risky (Westwood, 1993).

Practical advice for the gardener. If the climate in your region allows for annual fluctuations in ripening times, use a comprehensive approach to determine the harvest moment: first of all, rely on the starch-iodine test; second, on the change in ground color and seed color; and only third, on the calendar. This will allow you to pick the fruits in the optimal phase every year, regardless of weather whims (Tarasov et al., 1981).

How to Properly Pick Fruits

The correct picking technique aims to preserve the integrity of the fruit, its skin, and, most importantly, the stem. Tearing off the stem or damaging the skin is a "gateway" for infections that will lead to rotting during storage (Agustí, 2010).

The basic "lift and twist" technique (Phillips, 2005; Westwood, 1993). Grasp the apple so that it sits comfortably in your palm, with your index finger at the base of the stem, where it attaches to the fruit spur. Lift the fruit slightly upward while simultaneously twisting your hand so that the stem separates from the branch with a natural bend. This technique ensures a clean break in the area of the natural abscission layer that forms during ripening.

What not to do:

• Pull the fruit toward you or downward. With this motion, the stem most often breaks off at the base, and sometimes part of the fruit bud intended for next year's crop is torn off as well (Westwood, 1993; Phillips, 2005). In addition, sharp pulling increases the risk of skin damage.
• Squeeze the apple with your fingers. Strong compression leaves indentations (pressure marks) that are not immediately visible but lead to browning and rotting of the flesh in those places (Agustí, 2010).
• Twist the fruit around the stem. This technique often results in skin tearing at the calyx end and damage to the fruit.

Features for different types of orchards. In tall orchards with old trees, ladders are indispensable. A stepladder or a special orchard ladder must be stable. Never put fruits in your pockets or hold them between your body and the branches – this inevitably leads to damage. In low-stature orchards (on dwarf and semi-dwarf rootstocks), a significant portion of the crop can be picked from the ground, but for the upper branches, you will still need a lightweight stepladder or a pole pruner with a soft grip.

Handling the Harvest

Once an apple is picked from the branch, its quality depends solely on proper handling. Injuries sustained during picking or transferring do not heal and only worsen during storage.

1. Careful placement into containers. Picked fruits are never thrown – they are gently placed into a container. For collection, use picking bags with soft bottoms (canvas or fabric-lined) or buckets lined inside with soft material (Phillips, 2005). Do not shake the filled container; carefully empty it into a box or bin, allowing the fruits to roll smoothly rather than fall.

2. Choosing containers for picking. The best choice is shallow boxes or baskets in which apples lie in 2–3 layers. Deep containers (buckets, large baskets) cause the lower fruits to experience strong pressure and sustain micro-injuries (Agustí, 2010). Industrial orchards use bulk bins, but for a farm operation, boxes with a capacity of 10–15 kg are convenient. It is important that the walls and bottom of the containers are smooth, without burrs or protruding nails.

3. Protection from solar overheating. Immediately after picking, apples contain "field heat" – a temperature that can be several degrees higher than the air temperature. Leaving baskets in direct sunlight accelerates fruit aging and reduces storage life. Therefore, the harvested crop should be moved to shade or a cool room as quickly as possible (Agustí, 2010). Ideally, apples should be cooled to storage temperature within 24–48 hours after picking.

4. Sorting during picking. Experienced gardeners recommend separating damaged, wormy, and too-small fruits right during the picking process. This eliminates the need to sort and move apples again later in storage, thus reducing the risk of new damage (Phillips, 2005).

Common Harvesting Mistakes

Even with good theoretical knowledge, mistakes are often made in practice that negate growing efforts. Here are the most common ones:

Practical takeaway. The main principle of harvesting is "handle the apple like an egg." Any force, carelessness, or haste translates into losses during storage. Take time to train all family members or hired workers in the correct technique – this will pay off in long preservation of the harvest (Phillips, 2005; Westwood, 1993).

Why Sort Immediately After Harvest

The main reason is that damaged fruits are a source of infection for healthy ones. Fungal spores (especially Penicillium and Botrytis) spread rapidly in storage, and one rotten apple can infect neighboring ones (Agustí, 2010). Moreover, sorting fruits already in storage involves additional handling, which means a risk of new bruises. Therefore, it is optimal to carry out primary sorting directly in the orchard or immediately after delivering the crop indoors (Phillips, 2005).

Category 1: Fruits for Long-Term Storage

For long-term storage (from 2–3 to 6–8 months or more), only the best fruits that meet the following criteria are selected:

• Winter or autumn-winter ripening varieties. Summer apples are unsuitable for long-term storage (Westwood, 1993).
• Correct harvest maturity – starch-iodine test 3–4 points for winter varieties, 2–3 points for autumn varieties (Tarasov et al., 1981). Overripe fruits with signs of wateriness or mealiness are excluded.
• Intact skin and stem. The surface must have no punctures, scratches, cracks, or dents. The stem must be preserved – this reduces the risk of pathogen entry (Agustí, 2010).
• No signs of diseases or pest damage. Any spots, rotten areas, or wormholes make the fruit unsuitable for storage.
• Size. Medium and large fruits are preferred for storage – they better maintain turgor and marketable appearance. Too-small apples shrivel faster (Phillips, 2005).

Practical advice. Place selected apples in clean, dry boxes (preferably wooden or plastic with ventilation holes) in layers, interleaving with soft material (wood shavings, paper). Do not mix different varieties: they have different storage lives and times for reaching consumer maturity.

Category 2: Fruits for Processing

Apples that did not pass the selection for long-term storage but remain healthy and edible are excellent raw material for processing. This category includes:

• Fruits with minor surface defects – slight scab (a few small spots), mild deformation, poor blush, small scratches that do not penetrate the flesh (Phillips, 2005).
• Apples with a damaged stem – such fruits store poorly, but they are quite suitable for juice, compotes, jam, or drying (Agustí, 2010).
• Slightly overripe autumn variety fruits that will not withstand long storage but have not yet begun to spoil.
• Small fruits (smaller than the variety standard) – they make excellent juice or cider (Phillips, 2005).

For processing, it is important that the flesh is not rotten or severely damaged by pests. Apples with isolated wormholes can be used after cutting out the damaged areas.

Practical advice. For juice or cider production, try to blend varieties – this gives a richer, more balanced flavor. Varieties with high sugar and tannin content are especially valued (Phillips, 2005). Fruits for processing can be stored for a short time (up to 2–3 weeks) in a cool place, but it is best to process them as soon as possible.

Category 3: Damaged and Diseased Fruits

These are apples that are unsuitable for storage or processing for food purposes. They include:

• Fruits with deep cracks, skin tears – fungal infections enter through the damage.
• Apples with obvious signs of rotting (wet, brown, or moldy flesh) – such fruits become a source of infection (Agustí, 2010).
• Fruits with extensive pest damage (multiple wormholes, codling moth).
• Severely deformed, misshapen fruits with coarse, woody flesh.
• Windfalls – apples that have fallen to the ground. Even if they look intact, they may have invisible micro-damage and rot pathogens from the soil (Phillips, 2005).

Such fruits should be immediately removed from the general mass of the crop. They must not be left in storage or near healthy fruits. The best use is composting or feeding to animals (if there are no signs of toxic mold). Using windfalls for cider or juice is not recommended due to the risk of contamination by pathogens, including E. coli (Phillips, 2005).

How to Organize Sorting on a Farm

For a small orchard and farm operation, a simple sorting table with a soft covering is sufficient. Fruits are poured onto it from the picking containers and manually sorted, distributing them into three categories. It is important to work in a well-lit place and use clean hands or soft gloves to avoid damaging the skin (Phillips, 2005).

For large volumes, sorting can be done directly in the orchard: as the picker fills a bag, he visually evaluates each fruit and immediately culls obviously damaged ones. This saves time and reduces the number of transfers (Phillips, 2005).

Remember: apples intended for long-term storage must be selected particularly carefully. It is better to store fewer fruits for the winter, but of high quality, than to lay down questionable specimens and lose the entire supply due to the spread of infection (Agustí, 2010).

Temperature

Temperature is the main factor determining the duration of storage. As temperature decreases, all life processes in the fruits (respiration, ripening, senescence) slow down, and the development of pathogenic microorganisms is inhibited.

• Optimal range for most apple varieties – from 0 to +4 °C (Westwood, 1993). For winter varieties such as Antonovka, Severnyi Sinap, or Renet Simirenko, the best results are given by a temperature of 0 to +2 °C. At this temperature, fruit respiration is minimal, and they can be stored for 4–8 months or more.
• There are nuances for individual varieties. For example, McIntosh, Jonathan, and Newtown Pippin varieties are prone to flesh browning (internal browning) during long-term storage at about 0 °C. It is better to provide them with a slightly higher temperature – +2…+4 °C, although this reduces the storage period (Westwood, 1993; Agustí, 2010).
• Danger of negative temperatures. When the flesh freezes (below -1.5…-2 °C), cells are destroyed, and after thawing, the fruit becomes watery, soft, and unfit for eating. Even slight freezing leads to loss of firmness and flavor (Westwood, 1993).

Practical rule: aim for a stable temperature in the storage facility, without fluctuations of more than 0.5 °C. Sharp changes cause moisture condensation on the fruits, which provokes the development of rot (Agustí, 2010).

Air Humidity

The second most important parameter is relative air humidity (RH). Apples, like all fruits, continuously lose moisture through the skin, and if the air is too dry, they shrivel, lose firmness, and flavor.

• Optimal humidity for storing apples – 85–95% (Westwood, 1993). At this humidity, water loss is minimal, and the fruits remain juicy.
• At humidity below 80%, apples begin to wilt, the skin becomes wrinkled, and the flesh loses turgor. Varieties with thin skin, such as Golden Delicious or some russets, are particularly sensitive to this (Phillips, 2005).
• At humidity above 95%, the risk of mold and rot development increases, especially if there is skin damage.

How to maintain humidity at home. In a cellar or basement, you can place open containers of water, regularly moisten the floor, or use special humidifiers. In small refrigerators, it is recommended to store apples in perforated polyethylene bags (for gas exchange) to create a microclimate with high humidity inside (Phillips, 2005).

Ventilation

Apples are living organisms that, even at low temperatures, respire, absorbing oxygen and releasing carbon dioxide, ethylene, and water vapor (Westwood, 1993). If respiration products accumulate, fruit quality can deteriorate.

• Natural ventilation is necessary in any storage facility to remove excess carbon dioxide and ethylene, and to prevent stagnant moist air that promotes mold growth.
• In cellars and basements, supply-and-exhaust ventilation (vents, ducts) is sufficient. It is important that air can circulate around the boxes – do not place them flush against walls or each other; leave gaps.
• Ethylene is a gaseous hormone that apples release during ripening. It accelerates the senescence not only of the apples themselves but also of other fruits and vegetables stored nearby (Westwood, 1993). Therefore, it is not recommended to store apples in the same room as potatoes, carrots, cabbage, and especially pears, which are very sensitive to ethylene. The exception is if you deliberately want to accelerate ripening, but for long-term storage, this is harmful.

Practical advice: periodically ventilate the storage facility during cool times of the day (if possible) to refresh the air and remove accumulated ethylene. In industrial conditions, active ventilation systems or ethylene adsorbers are used.

Packaging

The packaging method affects apple preservation no less than the storage climate. Proper packaging protects fruits from mechanical damage, helps maintain humidity, and can even create a microclimate with a modified gas composition.

1. Boxes and containers. For farm operations, wooden or plastic boxes with ventilation holes, no more than 20–30 cm high, are optimal so that apples are layered no more than 3–4 layers. Too-deep containers lead to compression of lower fruits (Agustí, 2010).

2. Interleaving. To reduce friction and impacts between apples, they are interleaved (covered) with soft material:

• dry wood shavings (preferably from hardwood, without resin);
• crumpled paper or newspapers (but not glossy, as printing ink may release harmful substances);
• straw (preferably wheat or rye, clean and dry).
• me gardeners wrap each apple in thin paper – this is labor-intensive but significantly reduces damage and slows the spread of rot (Phillips, 2005).

3. Polyethylene bags. For small batches, a good method is to use polyethylene bags with several small holes (for gas exchange). Inside the bag, high humidity is created, which prevents wilting, while the gradual decrease in oxygen (due to respiration) and accumulation of carbon dioxide further slow ripening. Bags are tied loosely or left with holes. Such bags are convenient to store in the refrigerator or in a cool cellar.

4. Controlled atmosphere (CA). In large industrial operations, a more sophisticated method is used – storage in a controlled atmosphere with reduced oxygen (2–3%) and increased carbon dioxide (up to 5%), at a temperature of about 0 °C (Westwood, 1993). This significantly extends storage life but requires sealed chambers and special equipment, so this method is usually unavailable to farmers and hobbyists. However, the principle is the same: limiting oxygen access slows respiration and, consequently, fruit aging.

General Recommendations for Different Climatic Zones

• In regions with cold winters (temperate zone, Siberia), a cellar or basement with natural cooling is an ideal place. The main thing is to protect it from freezing (insulate it) and ensure ventilation.
• In regions with mild winters (southern Russia, Mediterranean), maintaining temperature in storage is more difficult. Refrigerated chambers or, for small volumes, household refrigerators can be used. Some gardeners store apples in trenches (pits) on the plot, but this method is risky due to groundwater and rodents.
• In tropical and subtropical regions (where apples do not grow, only stored), an electric refrigerator or renting a commercial climate-controlled warehouse is necessary.

The main rule of storage: the closer the conditions are to optimal (0–2 °C, 90% humidity, good ventilation), the longer the apples will remain fresh. If you cannot perfectly provide all parameters, try to maintain at least the temperature regime – this is the most important (Westwood, 1993; Agustí, 2010).

Mechanical Damage

This is the most common and at the same time the most preventable cause of losses. Any damage to the integrity of the fruit opens the gateway for infections and accelerates aging processes.

Bruises (dents). Occur from fruit falling, impacts against each other, strong finger pressure, or falling into containers. At the bruise site, cells are destroyed, phenolic compounds oxidize, and the flesh darkens. Even if the damage is externally invisible, after a few days or weeks, a brown spot appears at the bruise site, gradually enlarging (Agustí, 2010; Westwood, 1993). Bruises are especially dangerous during long-term storage, as fungal infections actively develop in damaged tissues.

Punctures and scratches on the skin. Occur from contact with branches, dry leaves, the picker's nails, or friction between fruits. Mold spores and bacteria easily penetrate through damaged skin (Agustí, 2010). A characteristic example is that apples with punctures are often affected by blue mold (Penicillium expansum), which quickly spreads to neighboring fruits.

Skin abrasion ("russeting" in the sense of skin scuffing). Occurs from friction of the fruit against a branch or rough container surface. Such areas become brown, dry out, but can serve as entry points for pathogens (Westwood, 1993).

How to prevent. The main thing is careful harvesting and handling. Use soft containers, do not throw fruits, do not overfill boxes, and interleave apples with soft material when storing (Phillips, 2005).

Storage Diseases

This is the main cause of mass losses, especially under conditions of insufficiently strict control. Pathogens that got onto the fruits in the orchard or during harvesting manifest themselves after a few weeks or months of storage.

The most common fungal diseases:

Prevention of storage diseases:

• Thorough sorting – removal of all fruits with suspicious spots.
• Harvest only in dry weather; store clean fruits.
• Rapid cooling after harvest to storage temperature (Agustí, 2010).
• Maintaining cleanliness in storage: regular disinfection, removal of rotten fruits when detected.
• In industrial conditions, permitted fungicides (e.g., thiabendazole or benomyl) are used, but for farm and hobby operations, sanitary measures and proper storage conditions are more important (Agustí, 2010).

Physiological Disorders

These are diseases not associated with pathogens but caused by disruption of physiological processes within the fruit itself. They often arise due to improper storage conditions or variety characteristics.

Violation of the Storage Regime

Even the best fruits will not withstand if the storage conditions do not meet the requirements. The most common errors and their consequences:

1. Too high temperature. Accelerates respiration and ripening; fruits quickly become soft, mealy, and lose juice and aroma. In addition, at temperatures above +5 °C, fungal diseases noticeably activate (Westwood, 1993).

2. Too low temperature (freezing). At -1.5…-2 °C, water in the cells freezes, ice crystals destroy cell walls. After thawing, the fruits become watery, lose consistency, and rot quickly (Westwood, 1993).

3. Temperature fluctuations. Cause condensation of moisture on the surface of the fruits ("sweating"). A moist environment is an ideal condition for the development of mold (Agustí, 2010).

4. Insufficient air humidity. Leads to wilting and shriveling of the fruits. Varieties with thin skin are particularly affected (Phillips, 2005).

5. Improper ventilation. Stagnant air promotes the accumulation of ethylene, which accelerates ripening and senescence. At the same time, in poorly ventilated storage, humidity rises, which favors fungal infections (Westwood, 1993).

6. Storing together with products that release ethylene. Pears, apples of other varieties with earlier ripening, tomatoes, melons release significant amounts of ethylene, accelerating senescence and impairing quality. Particularly harmful is proximity to potatoes, which impart an unpleasant earthy taste to apples (Phillips, 2005).

How to avoid errors:

• Install a thermometer and hygrometer in the storage and regularly monitor the parameters.
• Maintain a stable temperature.
• Ensure air circulation; do not block passages.
• Store apples separately from other fruits and vegetables.
• Regularly (at least every 2–4 weeks) inspect the apples and remove suspicious and rotten fruits to prevent the spread of infection (Agustí, 2010).

How to Minimize Losses: Summary of Key Measures

Practical takeaway. Storage losses are inevitable, but most of them are preventable. The main enemies are mechanical damage, fungal infections, and improper regime. Attention to detail at all stages – from choosing the harvest date to weekly inspection of the stored produce – allows preserving up to 80–90% of the winter apple harvest even in a small farm or hobby orchard (Agustí, 2010; Phillips, 2005; Westwood, 1993).