Physiological disorders

1. What Are Physiological Disorders? And How Do They Differ from Diseases?

Imagine this: you have grown potatoes, but the tubers turn out misshapen, with cracks, green patches, or hollow centres. It looks like a disease, but in fact it may not be. The cause is often not viruses or fungi, but your own mistakes in care or unfavourable weather conditions. In agronomy, such defects are called physiological disorders (Mikitzel, 2014).

What is the main difference from diseases?

• Cause. Diseases are caused by living pathogenic organisms: fungi, bacteria, viruses, or nematodes (Popkova et al., 1980). Physiological disorders are the result of abiotic stress, i.e., the impact of non‑living factors: improper moisture, overheating, nutrient deficiency, or mechanical damage.
• Infectiousness. Diseases are contagious and can spread from plant to plant. Physiological disorders do not spread. Even if you grow a few misshapen tubers, neighbouring plants will not be affected unless you repeat the same mistakes.
• Reversibility. Infectious diseases are generally irreversible. In many cases, physiological disorders can be prevented or, if they occur, their consequences can be minimised in the next season through proper agronomic practices (Dean, 1994).

Why do physiological disorders occur?

Most of them are the plant's response to stress. Potato is a very sensitive crop, and any abrupt change in conditions is perceived as a threat, which affects tuber development (Welbaum, 2015).

The main causes can be grouped into four categories:

1. Moisture stress. Alternation of drought and severe waterlogging. This is the most common cause of deformities and cracks (Navarre & Pavek, 2014).

2. Temperature stress. Too hot or, conversely, too cold weather, especially in early and mid‑season.

3. Nutritional imbalance. Excess or deficiency of key elements such as nitrogen, potassium, and calcium. For example, over‑feeding with nitrogen often leads to vigorous foliage growth at the expense of tuber quality (Popkova et al., 1980).

4. Mechanical damage. Bruising, compression, cuts during harvesting or sorting.

The grower's golden rule: to obtain healthy, smooth, and tasty tubers, strive to provide plants with the most stable and comfortable conditions throughout the growing season. In the following chapters, we will examine how to avoid the most common physiological disorders and what to do if they have already appeared.

2. Greening of Tubers: Why Potato Becomes “Poisonous” and How to Prevent It

You have certainly come across this sight: when harvesting or in storage, among the usual tubers, you suddenly find a potato with green “sides.” It looks unappetising, and for good reason. Such potatoes should not be eaten, and the cause here is not a fungus or virus, but a plain violation of growing and storage conditions.

Why does potato turn green?

Greening is the tuber's protective reaction to light. Like all plants, potato reaches for light, and if a tuber is on the surface or under a thin layer of soil through which sunlight penetrates, its skin begins to produce a pigment – chlorophyll. As in leaves, it is responsible for photosynthesis and colours the tissues green (Mikitzel, 2014).

This process is triggered even by small amounts of light: an illumination of 3–11 W/m² for 24 hours is enough to start greening. It happens fastest at temperatures above +13 °C (Navarre & Pavek, 2014). White‑skinned varieties are more prone to greening than red or russet‑skinned ones (Jong et al., 2011).

What is the danger of green potato?

The danger of the green colour is not in chlorophyll itself – it is harmless. The problem is that chlorophyll synthesis is always accompanied by the accumulation of another substance – solanine. This is a natural poison that potato produces to protect itself from insects and diseases (Welbaum, 2015).

• Solanine gives potato a bitter taste.
• In high concentrations, it can cause serious poisoning in humans.
• The skin and flesh of green potato must be cut off. If greening has penetrated deeply, such a tuber should be discarded without regret.

Where does greening most often occur?

In the field. Tubers that have surfaced. This happens due to:

• Too shallow planting.
• Improper or insufficient hilling.
• Cracking of soil during dry periods, through which light penetrates.
• Heavy rains that wash away ridges and expose young tubers.

After harvest. If you leave harvested potatoes in the light, for example, drying them in the open or storing them in transparent containers in a lit place. Artificial light also causes greening, although more slowly than sunlight (Navarre & Pavek, 2014).

How to prevent greening: 3 golden rules

1. Planting depth and proper hilling. Plant potatoes at a depth of at least 8–10 cm, and as the plants grow, be sure to hill them. This creates a reliable layer of soil that acts as a shield against light.

Why this matters: Even 2–3 cm of extra soil above the tuber will protect it from ultraviolet rays and prevent the synthesis of both chlorophyll and solanine.

2. Mulching. In hot climates or during dry periods, a layer of mulch (grass, straw) will not only help retain moisture but also prevent cracks in the soil through which light can reach the tubers. In addition, mulch creates an additional light‑impermeable barrier.

3. Darkness during storage. This is the most important rule. Store potatoes only in complete darkness. Use opaque bags, boxes, or a windowless storage facility. Do not dry washed potatoes in the sun and do not keep them in transparent bags in a lit kitchen.

Why this matters: The greening process in storage can begin within a few days, especially in a warm room.

What to do if potatoes have already turned green?

Such potatoes can still be used if the greening is superficial. Carefully cut off the green skin and the layer of flesh underneath (1–2 cm deep). If the spots have penetrated deeply and the tuber has acquired a bitter taste, use it only for planting, not for food (Jong et al., 2011). Green potato is absolutely unsuitable for boiling or frying.

3. Cracking of Tubers: When Potato “Bursts” from Stress

Have you ever dug up potatoes and seen deep cracks on them, as if someone had cut them with a knife? Such defects not only spoil the appearance but also open the door to infections, reducing the storability of the tubers. This is not a disease, but a classic physiological disorder that signals that the plant has experienced severe water stress.

Why do tubers crack?

The main cause is sharp fluctuations in the growth rate of tubers caused by unstable moisture supply (Mikitzel, 2014).

The process looks like this:

1. Drought period. In dry and hot weather, tuber growth slows down or stops completely. The skin (periderm) loses elasticity and becomes rough.

2. Sudden watering or heavy rain. After a long drought, the plant throws all its energy into tuber growth, trying to catch up. The tuber begins to accumulate water and swell rapidly.

3. Rupture. The internal pressure in the tuber becomes so strong that the rough, inelastic skin cannot withstand it and bursts. This is how growth cracks appear (Dean, 1994).

These cracks may be superficial and eventually heal, but they are often deep, penetrating the flesh, making the tuber unsuitable for long‑term storage and spoiling its marketable appearance.

Factors that increase the risk of cracking:

• Varieties with elongated tubers. They are more prone to cracking than round‑tubered varieties (Navarre & Pavek, 2014).
• Wide spacing. If plants are planted too sparsely, they have more resources for rapid growth of individual tubers, which increases the risk of cracks during moisture fluctuations.
• Uneven fertilisation. Fluctuations in nutrient availability can also provoke uneven growth.

Differences from other cracks

It is important not to confuse growth cracks with “nail” cracks (air checks). The latter are superficial arc‑shaped ruptures of the skin that occur not from growth, but from careless handling of cold, very juicy tubers (mechanical impact during harvesting). They are shallow and heal faster (Mikitzel, 2014).

How to prevent cracking: 4 steps to stability

1. Regular watering. This is the most important point. Instead of heavy watering once a week, it is better to water more frequently but moderately. The goal is to maintain soil moisture at a stable level, avoiding complete drying of the root zone. The period from flowering to the beginning of tuber maturation is especially critical.

Why it works: Uniform moisture ensures smooth tuber growth, and the skin has time to adapt to the increasing volume.

2. Mulching. A layer of organic mulch (straw, grass, sawdust) helps retain moisture in the soil, preventing its sharp drying out. It also softens temperature fluctuations and protects the soil from crust formation.

3. Proper planting. Follow the recommended planting density for your variety. Do not plant too sparsely – this reduces the risk that individual tubers will grow too fast and “burst.”

4. Careful cultivation. Try not to damage the root system, as this can exacerbate stress. In hot periods, limit inter‑row cultivation to avoid drying out the soil.

What to do if cracks have already appeared?

Deep cracks do not heal completely, and such potatoes should not be stored for long periods. Use them first. However, if the cracks are superficial, they may be covered with cork tissue, and the tuber will be quite edible, although it will lose its marketable appearance (Jong et al., 2011). The main takeaway: stability is the key to a healthy harvest.

4. Hollows Inside Tubers: When Potato “Eats” Itself

You cut open a large, beautiful‑looking tuber, and inside there is a cavity or brown rotting tissue. Familiar? This is not a disease, but a physiological disorder called hollow heart or its precursor – brown centre. Such tubers are unsuitable for long‑term storage and lose marketable quality, although they can be eaten after cutting out the damaged parts.

What are brown centre and hollow heart?

• Brown centre is the initial stage. A small area of dead, browned tissue appears in the centre of the tuber. It is firm to the touch. This is cell damage that occurs when the tuber is still very small – at the setting stage, when it weighs less than 50–60 g (Mikitzel, 2014).
• Hollow heart is a consequence of brown centre. If after cell damage the tuber begins to grow rapidly, the living tissues around the dead area grow faster, and a cavity – a “hollow” – forms in the centre. It may be star‑shaped, slit‑like, or irregular. Sometimes the cavity is lined with cork tissue (Jong et al., 2011).

Interestingly, hollow heart can be of two types:

• At the stem end – occurs at the very beginning of tuber growth, often after a cold period.
• At the apical (bud) end – develops later, during the active bulking phase, and is more often associated with sharp fluctuations in moisture or nutrition (Mikitzel, 2014).

Why do hollows form?

As with cracking, the root of the problem is uneven growth, but here it manifests inside the tuber. A classic scenario:

1. Stress early in growth. Cold weather (soil temperature around +10…+15 °C) at the time of tuber setting damages cells in the centre – brown centre develops (Mikitzel, 2014).

2. Sharp improvement in conditions. After a stress period, warmth, moisture, and abundant nutrition arrive. The tuber starts growing vigorously, but the damaged central tissue cannot keep up with the growth of the peripheral layers. As a result, the centre “tears,” forming a cavity.

Why it works: Young, actively dividing cells of the periphery grow faster than damaged cells in the centre. This creates internal tension that leads to rupture.

Factors that increase the risk:

• Variety. Some varieties are more prone to hollow heart. For example, `Russet Burbank` and `Yukon Gold` are highly susceptible to this disorder (Navarre & Pavek, 2014; Mikitzel, 2014).
• Tuber size. The larger the tuber, the higher the risk. Hollow heart is a disease of “record‑holders” (Jong et al., 2011).
• Excess nitrogen. Particularly dangerous is the application of large doses of nitrogen at the beginning of tuber formation – this provokes rapid growth and increases the risk of tearing (Mikitzel, 2014).
• Wide spacing. Sparse planting promotes the formation of large tubers, thus increasing the risk of hollow heart.
• Deficiency of potassium and calcium. Potassium regulates water balance, and calcium strengthens cell walls. Their deficiency makes tissues more vulnerable (Mikitzel, 2014).

How to prevent hollows: 5 practical tips

1. Choose resistant varieties. The most reliable method. If hollow heart is a frequent problem in your region, prefer varieties with round tubers and medium size. Avoid varieties prone to producing very large tubers (Jong et al., 2011).

2. Do not delay planting. In regions with cold springs, try to plant potatoes when the soil has warmed up sufficiently. This reduces the risk of cold damage at the tuber‑setting stage.

3. Uniform watering. As with cracking, avoid sharp fluctuations in moisture. Stable moisture is the key to even growth.

4. Balanced nutrition. Do not over‑feed with nitrogen, especially at the start of tuber growth. Ensure adequate potassium, especially on light soils. Potassium improves tissue structure and reduces the risk of tearing (Welbaum, 2015).

5. Optimal planting density. Too sparse planting is a path to giant tubers with hollows. Follow the recommended spacing for your variety.

What to do if you find a hollow tuber?

Do not discard the harvest! Such tubers can be used:

• Cut out the damaged areas and use the healthy flesh for boiling, frying, or mashing.
• Keep for seed (if the cavity is not too large) – seed quality does not suffer from hollow heart (Mikitzel, 2014).
• The main thing is not to store such tubers for long periods, as pathogens of rots can enter through the damaged tissues.

5. Secondary Growth of Tubers: When Stress Turns Potato into a “Monster”

Sometimes during harvest you can find tubers of the most bizarre shapes: they resemble dumbbells, hourglasses, or are covered with many small “offsets.” This is not the result of pests or diseases, but a classic example of a physiological disorder called secondary growth. This phenomenon is a vivid example of how a plant tries to survive under stressful conditions by reprogramming its development.

What is secondary growth?

Secondary growth is the resumption of tuber growth after it has been arrested, or conversely, the formation of new tubers on already formed ones. Instead of quietly bulking, the tuber starts to “misbehave”: its eyes produce stolons on which new small tubers set, or the tuber itself begins to grow unevenly, producing ugly outgrowths (Mikitzel, 2014).

Three main types of secondary growth

1. Heat sprouts. From stolons or eyes of the tuber, short shoots grow that break through the soil surface and turn into ordinary green stems. It looks as if the tuber decided to sprout right in the field, without waiting for harvest.

2. Chain tubers. On one stolon, not one but several tubers are formed, connected to each other. The result is a “sausage” of 2–3 potatoes.

3. Little tubers (offsets). From the eye of the mother tuber, without producing a normal sprout, several small tubers are formed at once. This often happens before planting or immediately after planting in cold, wet soil (Jong et al., 2011).

Why does this happen? Classic stress physiology

The main culprit of this disorder is high soil temperature (above +28 °C), especially combined with other stress factors: drought, moisture fluctuations, excess nitrogen (Mikitzel, 2014).

The mechanism is simple:

1. Hormonal disruption. Normally, the tuber has a high level of the hormone abscisic acid (ABA), which promotes starch accumulation and tuber growth. Under stress (heat, drought), ABA levels decrease and levels of another hormone – gibberellin (GA) – increase (Dean, 1994).

2. Program switch. Gibberellin is a hormone of stem and stolon growth. When it becomes abundant, the tuber ceases to be a tuber. It “remembers” that it is an underground stem and begins to behave accordingly: sprout, produce new stolons, and form new tubers or shoots.

Why it works: Nature has built into potato a survival mechanism: if conditions are too harsh, it is better to “give birth” to a new generation at a more favourable time than to try to mature under current conditions.

How to prevent secondary growth: 5 key strategies

1. Mulching to cool the soil. In hot regions, this is a lifesaver. A layer of organic mulch (straw, grass, mown green manure) lowers soil temperature by 3–5 °C, protecting tubers from overheating.

2. Regular watering. In hot weather, it is especially important not to let the soil dry out. It is the combination of overheating and lack of moisture that creates ideal conditions for secondary growth.

Why this matters: Water in the soil acts as a heat accumulator – moist soil heats up more slowly than dry soil.

3. Balanced nitrogen nutrition. Excess nitrogen, especially during tuber formation, stimulates gibberellin production and provokes secondary growth. Use nitrogen fertilisers in a measured way, giving preference to potassium fertilisers (potassium increases stress resistance) (Popkova et al., 1980).

4. Proper storage of seed potatoes. Store seed material at +3…+4 °C. High temperatures (+20 °C and above) accelerate tuber ageing, which can lead to the formation of “offsets” when planted in cold soil (Navarre & Pavek, 2014).

5. Choice of resistant varieties. Some varieties are more prone to secondary growth than others. In regions with hot climates, prefer varieties tolerant to high temperatures.

What to do if secondary growth has already occurred?

Unfortunately, the situation cannot be corrected in the current season. Ugly tubers can be eaten (they are safe), but do not store them for long periods. However, seed material from such plants is not recommended – it will produce weak, uneven seedlings and inherit the tendency to this problem (Popkova et al., 1980).

Important note: The main cause of secondary growth is combined stress, not just one factor. Therefore, a one‑off action is not enough; an integrated care system is essential: regular watering, mulching, proper nutrition, and variety selection. Together, they create comfortable conditions and prevent the plant from “panicking.”

6. Flesh Discolouration: When Potato “Turns Blue” from Bruising and Stress

Have you ever peeled potatoes and noticed dark, bluish‑grey or even black spots on the flesh? Or perhaps after cooking, the potato turned unnaturally dark? This is not spoilage or disease, but a physiological disorder called flesh discolouration (blackspot bruise or after‑cooking darkening). It does not make the potato poisonous, but it significantly spoils its appearance, taste, and market value.

Two main types of discolouration

It is important to distinguish between these two types, as their causes are completely different:

1. Blackspot bruise – arises from mechanical impact. When a tuber hits a hard surface, cells at the impact site are destroyed, and the enzyme polyphenoloxidase reacts with the amino acid tyrosine to form a dark pigment melanin (Dean, 1994). This appears as grey, bluish, or black spots under the skin.

2. After‑cooking darkening – appears after heat treatment. The potato darkens during boiling or frying due to a chemical reaction between chlorogenic acid and iron, which is accelerated by potassium deficiency or improper storage (Jong et al., 2011; Mikitzel, 2014).

Why do blackspot bruises occur?

This is the most common problem, especially with mechanised harvesting. The main causes:

• Low tuber temperature at harvest. Cold tubers (below +10 °C) are more brittle and sensitive to impacts (Mikitzel, 2014).
• Potassium deficiency. Potassium strengthens cell walls and reduces tissue vulnerability. In its deficiency, discolouration is more pronounced (Dean, 1994).
• Variety. Some varieties are more prone to flesh discolouration due to high tyrosine content. For example, `Atlantic` is very susceptible to this problem (Navarre & Pavek, 2014).
• Tuber maturity. Immature tubers with undeveloped skin are less resistant to bruising than mature ones (Mikitzel, 2014).
• Low calcium content. Calcium strengthens cell walls. Studies show that when the calcium concentration in the flesh is less than 200–250 ppm on a dry‑weight basis, the risk of discolouration increases significantly (Mikitzel, 2014).

Why does potato darken when cooked?

• Potassium deficiency. This is the main cause. When potassium is lacking, free sugars and amino acids accumulate in the tubers, which react upon heating (Jong et al., 2011).
• Low storage temperature. Storage below +4 °C causes starch to convert to sugars, which also causes darkening during cooking (Welbaum, 2015).
• Phosphorus deficiency. Lack of phosphorus can also contribute to this problem (Popkova et al., 1980).

How to prevent flesh discolouration: 5 practical tips

1. Careful harvesting. This is the most important point. Try to:

• Harvest when tuber temperature is at least +10 °C. If harvesting in cold weather, let the tubers warm up in the air.
• Minimise tuber drops during harvesting. Use soft surfaces, reduce drop height (Navarre & Pavek, 2014).
• Do not overload containers so that tubers do not press on each other.
• Potassium fertilisation. Provide plants with sufficient potassium (at least 200–250 kg K₂O per hectare). Potassium is the main defender against discolouration.

Why this matters: Potassium strengthens cell walls and reduces tissue vulnerability to mechanical damage, and also reduces the tendency to after‑cooking darkening (Popkova et al., 1980; Dean, 1994).

3. Proper storage. Store potatoes at +4…+8 °C. Lower temperatures lead to sugar accumulation and darkening during cooking. If potatoes have been stored cold, keep them at room temperature for 1–2 weeks before use – this allows the sugars to convert back to starch (Welbaum, 2015).

4. Balanced nutrition. Do not over‑feed with nitrogen, especially during tuber formation. This leads to accumulation of free amino acids and increases the risk of discolouration (Mikitzel, 2014).

5. Variety choice. If the problem is recurrent, choose varieties resistant to flesh discolouration. For example, `Russet Burbank` has moderate resistance, while `Atlantic` is very sensitive (Jong et al., 2011).

What to do if potatoes have already darkened?

• Bruises. Darkened areas can be cut out; the remaining flesh is edible. However, such potatoes should not be stored for long – damaged tissues can become entry points for infections.
• After‑cooking darkening. Not dangerous to health, but looks unappetising. When boiling, you can add a few drops of lemon juice or vinegar to the water – this will reduce the intensity of darkening (Jong et al., 2011).

Important nuance: There is also “white knot” – a type of injury in which dense, hard areas consisting of large starch grains form in the flesh. This occurs from severe impacts and is especially characteristic of the `Atlantic` variety (Mikitzel, 2014). Such potatoes produce hard spots when frying and chipping, making them unsuitable for processing.

Main takeaway: Flesh discolouration is not a death sentence, but a signal that more attention should be paid to harvesting, plant nutrition, and storage conditions. Gentle handling and balanced nutrition are the two pillars of protection against this problem.

7. Misshapen and Deformed Tubers: When Potato “Grows” Crooked

You have certainly seen strange, ugly tubers that look more like alien objects than potatoes: with outgrowths, constrictions, curved and whimsically twisted. This is not a mutation or disease, but a classic physiological disorder known as tuber malformations or simply knobbiness (Jong et al., 2011). Such tubers lose marketable appearance and may be unsuitable for sale, although their flesh often remains perfectly edible.

Main types of deformities

1. Knobby tubers. The tuber develops “bumps” resembling fingers or horns. These are secondary growths that arise from eyes when the growth of the main tuber has been disrupted (Mikitzel, 2014).

2. Dumbbell‑shaped tubers. Have a constriction in the middle, resembling a dumbbell or hourglass.

3. Pointed‑end tubers. One end of the tuber narrows sharply and often becomes “glassy” and translucent.

4. Bottleneck tubers. The constriction is located closer to one end, usually the stem end.

5. General irregularity. The tuber surface becomes bumpy, wavy, losing its normal shape (Navarre & Pavek, 2014).

Why do tubers become misshapen? Causes of deformities

All these deformities are the result of interruption and resumption of tuber growth. When a tuber begins to form, its elongation occurs through cell division at the tip (apical part). If growth is interrupted and then resumes, new cells may start dividing not in the same direction but sideways, creating outgrowths. Alternatively, if growth stops and resumes differently in different parts of the tuber, constrictions and curvatures arise (Dean, 1994).

The main causes of growth interruption:

1. Irregular watering and moisture fluctuations. This is the main cause of deformities. Alternating drought and heavy rains create ideal conditions for ugly tubers (Mikitzel, 2014).

2. Soil compaction. Heavy, dense, clayey soil mechanically hinders tuber growth, forcing them to curve and take strange shapes (Popkova et al., 1980).

3. High temperature. Heat, especially combined with drought, stops tuber growth. When weather changes, growth resumes, but with deformities.

4. Potassium deficiency. Potassium regulates cell water balance and participates in carbohydrate metabolism. Its deficiency makes tissues more vulnerable to stress and intensifies deformities (Welbaum, 2015).

5. Wide spacing. Sparsely planted plants produce fewer tubers, but they grow faster and larger. Such tubers are most often deformed.

6. Pest damage. Some pests, such as wireworms, can damage young tubers, leading to distorted growth.

Which varieties are more susceptible to deformities?

• Varieties with long tubers. They deform much more often than round‑tubered varieties. The clearest example is `Russet Burbank`, which is very prone to knobs and curvatures (Mikitzel, 2014).
• Varieties with large tubers. They are more sensitive to stress during growth.

How to prevent deformities: 5 steps to smooth tubers

1. Stable watering. This is the most important and most effective measure. Instead of rare heavy watering, practice more frequent but moderate watering. Ideally, drip irrigation, which ensures constant soil moisture.

Why it works: Constant moisture allows tubers to grow evenly, without stops and spurts.

2. Loose soil. Avoid soil compaction. Regular inter‑row cultivation and application of organic matter (compost, manure) improve soil structure and facilitate tuber growth.

3. Potassium fertilisation. Potassium not only strengthens cells but also improves the water balance of plants. Apply potassium fertilisers (potassium sulphate, potassium magnesia) during tuber formation and growth.

Why this matters: Potassium increases plant stress resistance and helps them survive dry periods without serious consequences (Popkova et al., 1980).

4. Optimal planting density. Do not plant potatoes too sparsely. Follow the recommendations for your chosen variety. Denser planting reduces the risk of giant, and therefore ugly, tubers.

5. Choice of resistant varieties. If deformities are a frequent problem in your region, choose varieties with round tubers that are stress‑tolerant and not prone to outgrowths.

What to do if tubers have already grown misshapen?

• Use for food. Such tubers are perfectly edible if they have no other defects. Use them for boiling, mashing, or frying (after peeling and cutting, shape does not matter).
• Do not keep for seed. Misshapen tubers should not be used as seed material – they often inherit this tendency and produce weak plants with reduced productivity (Jong et al., 2011).
• Animal feed. If the tubers are severely deformed, they can be used as feed for farm animals.

Conclusion Across All Chapters

We have covered seven main types of physiological disorders of potato. Each of them is the result of stress: improper watering, overheating, poor nutrition, or careless harvesting.

Key lessons for the grower:

1. Stability is the key to success. Potato likes uniformity: consistent moisture, stable temperature, balanced nutrition. Any sharp changes are stress that leads to tuber defects.

2. Potassium is your main ally. This element strengthens cells, increases stress resistance, and reduces the risk of most disorders.

3. Careful handling during harvesting. Bruises and cuts are gateways for rots and a cause of flesh discolouration. Handle potatoes gently!

4. Proper storage. Darkness, moderate temperature (+4…+8 °C), and good ventilation are the foundation of crop preservation.

5. Variety selection. Consider the susceptibility of varieties to various disorders. If your region is often hot, choose heat‑tolerant varieties; if moisture problems exist, choose varieties resistant to deformities.

Remember: physiological disorders are not contagious and are not dangerous to health if damaged parts are removed in time. But they signal weak points in potato care. Analyse your mistakes, adjust your agronomic practices – and in the next season you will harvest smooth, beautiful, and healthy tubers!

Summary Table for Quick Diagnosis

References

1. Dean, B.B. (1993). ‘Anatomy and Morphology: Growth and Development’, in Managing the Potato Production System. New York: Routledge, pp. 51-68.
2. Dean, B.B. (1993). ‘Physiological Disorders’, in Managing the Potato Production System. New York: Routledge, pp. 125-134.
3. Jong, H.De., Sieczka, J.B., Jong, W.De. (2011). ‘Pests and Other Problems’, in The Complete Book of Potatoes. What Every Grower and Gardener Needs to Know. Portland, London: Timber Press, pp. 89-113.
4. Mikitzel, L. (2020). ‘Tuber Physiological Disorders’, in Navarre, R., Pavek, M.J. (ed.) The Potato. Botany, Production and Uses. Boston, MA: CABI, pp. 237-254.
5. Welbaum, G.E. (2015). ‘Family Solanaceae’, in Vegetable production and practices. Boston, MA: CABI, ch. 11.
6. Попкова, К.В., Шнейдер, Ю.И., Воловик, А.С., Шмыгля, В.А. (1980). Болезни картофеля. null Москва: Колос.