Physiological disorders

What is a Physiological Disorder?

A physiological disorder is a non-infectious injury to a plant. It does not arise from attacks by fungi, bacteria, or viruses, but rather from unfavorable environmental factors, improper care, or nutritional imbalances (Bosland and Votava, 2012). It is a kind of "malfunction" in the pepper's normal life processes, caused by abiotic (non-living) stress.

Think of it this way: a human can get a fever from a cold (an infection) or from overheating in the sun (a non-infectious heat effect). The external symptoms might look similar, but the causes and the methods of help are fundamentally different. The same applies to plants.

The main causes of physiological disorders include:

• Extreme temperatures (both too high and too low for peppers).
• Improper watering (insufficient or excess moisture, sharp fluctuations).
• Unbalanced nutrition (deficiency or excess of specific elements, such as calcium or nitrogen).
• Light damage (e.g., sunscald).
• Soil problems (salinization, incorrect pH, root damage) (Wien and Stützel, 2020).

The Main Difference from Disease

This is the most crucial point. Your ability to distinguish a physiological disorder from a disease will determine your strategy for saving the harvest.

The main difference: a physiological disorder is NOT contagious.

Here are the key criteria for differentiation:

1. Nature of the Agent:

• Disease: Caused by a living pathogen (fungus, bacterium, virus, phytoplasma) that reproduces and spreads.
• Physiological Disorder: Caused by an abiotic (non-living) factor, such as heat or lack of water.

2. Spread:

• Disease: Generally transmits from plant to plant. Infections often appear in foci that gradually expand. Their spread is facilitated by wind, water, insects, or your tools.
• Physiological Disorder: Does not transmit. Symptoms usually appear on many plants simultaneously or across the entire plantation if a common factor (e.g., drought or hail) is affecting them. As a rule, there's no clear pattern of spread from a diseased plant to a healthy one.

3. External Signs:

• Disease: Often accompanied by signs of the pathogen's presence: fungal spores (mold, mildew), a rotting smell, necrosis with a clear boundary between healthy and diseased tissue, and sometimes spots on leaves with characteristic concentric rings (Kemble et al., 2022).
• Physiological Disorder: Manifests as general stress. This can be wilting, discoloration (yellowing, browning) of leaves or fruits, growth arrest, flower and fruit drop, and fruit deformation (Bosland and Votava, 2012). Symptoms are often linked to specific plant parts (e.g., blossom-end rot only on the fruit tips) or specific weather conditions.

Why is this Important for the Gardener?

Understanding these differences gives you a huge advantage. Instead of fruitlessly treating your plants with fungicides (against fungi) or insecticides (against insects that carry diseases), you'll be able to correct the true cause of the problem—adjusting watering, fertilization, or providing shade.

An accurate diagnosis is the key to correct and effective treatment.

In the following chapters, we will examine the most common physiological disorders of pepper—from blossom-end rot to fruit cracking—in detail, and find out how to prevent them and how to manage them if they appear.

What is it and what does it look like?

Blossom-end rot appears as a dry, dark, sunken, and leathery patch on the fruit. In peppers, unlike tomatoes, this spot typically occurs not right on the tip (blossom end) but on the side surface, closer to the flower end of the fruit (Bosland and Votava, 2012). The spot can be from 0.5 to 8 cm in length. The affected tissue shrivels and becomes flat or even concave. Fruits with such defects often ripen prematurely, and secondary fungi may colonize the affected areas, although they are not the cause of the problem (Bosland and Votava, 2012).

The Main Cause – Calcium Deficiency in the Fruit

Despite its appearance, blossom-end rot is caused by a localized lack of calcium (Ca) in the fruit (Santos, 2012; Wien and Stützel, 2020). Calcium is a vital building material for cell walls. It is involved in cell division and ensures tissue strength. When it is deficient, the actively growing tissues of the fruit weaken, fail to develop normally, and die.

It's important to understand: calcium is a "lazy" element. It moves very poorly within the plant, especially from older leaves to young fruits. Therefore, calcium deficiency in fruits can occur even when there is enough of it in the soil (Pilbeam and Morley, 2007; Taylor and Locascio, 2004).

What Triggers Blossom-End Rot?

Blossom-end rot is not just a lack of calcium in the soil. It is a disruption in the transport of calcium to the rapidly growing fruits. The following factors can trigger this failure (Wien and Stützel, 2020; Bosland and Votava, 2012):

1. Inconsistent Watering. This is the primary cause. Calcium enters the plant with water through the roots. When the soil dries out, the movement of water and the calcium dissolved in it towards the fruits slows down dramatically. The alternation of drought and heavy watering is the ideal scenario for blossom-end rot development. Large-fruited varieties are particularly vulnerable.

2. Excessive Nitrogen Nutrition. Over-application of nitrogen fertilizers, especially in the ammonium form, stimulates vigorous growth of foliage and fruits but simultaneously disrupts calcium uptake. Nitrogen "blocks" calcium in the roots and older leaves (Santos, 2012; Bar-Tal et al., 2001).

3. Competition with Other Cations. High levels of potassium (K) and magnesium (Mg) in the soil can compete with calcium for root uptake, exacerbating its deficiency (Hamilton and Ogle, 1962; Santos, 2012).

4. Root Damage. Cultivating too close to the stem, planting in cold or waterlogged soil damages the absorbing rootlets, reducing the plant's ability to take up water and nutrients.

5. Extreme Temperatures. High temperatures increase transpiration (evaporation) from the leaves, and water with calcium is drawn towards the leaves, "shortchanging" the fruits.

Prevention – The Foundation of Control

Preventing blossom-end rot is much easier and more effective than treating already affected fruits. Here are the main preventive measures:

1. Consistent Watering. This is the most important rule. The soil in the root zone should always be evenly moist. Do not allow strong fluctuations between drought and "flooding." Use mulch (straw, grass clippings, agrotextile) to retain moisture and prevent root overheating. It has been shown that even water stress imposed during the fruiting period can trigger blossom-end rot (Wien and Stützel, 2020).

2. Balanced Nutrition. Avoid excessive nitrogen fertilization, especially in the second half of the growing season when the fruits are setting. Prefer nitrogen in the nitrate form (calcium nitrate), which promotes better calcium uptake.

3. Correct Soil pH. The optimal pH level for peppers is between 6.0 and 7.5 (Santos, 2012). In overly acidic (pH below 6.0) or overly alkaline soil, calcium availability to the roots decreases. If necessary, carry out liming.

4. Gentle Cultivation. Loosen the soil carefully, trying not to damage the root system.

Emergency Measures: What to Do if Rot Appears?

If characteristic dark spots have already appeared on the fruits, you cannot restore their marketable appearance. Such fruits should be removed, as they will not ripen properly. However, the main goal is to save the future harvest.

1. Immediately Adjust Watering. Check the soil moisture. If it has dried out, moisten it gradually, avoiding a sharp overwatering.

2. Foliar Calcium Spray. This is an emergency measure. Spray the plants on the leaves with a solution of calcium nitrate (1-2 tablespoons per 10 liters of water). This won't radically solve the problem but will help "deliver" calcium to the fruits faster than through the roots.

3. Temporary Shading. If there is intense heat, shade the plants for a few days to reduce evaporation and direct water towards the fruits.

Remember: blossom-end rot is a signal that your plants are experiencing stress. By responding correctly, you will maintain plant health and get a good harvest of healthy fruits in the future.

---

Article Title for the Series: When Peppers Get Sick Without Diseases: How Weather, Watering, and Nutrition Affect Your Harvest.

Chapter Title: Chapter 3. Sunscald: When the Sun Becomes an Enemy.

---

What does it look like?

On the fruit, usually on the side facing the sun (most often the southwest side), an area with pale, discolored, and subsequently necrotic (dead) tissue appears (Bosland and Votava, 2012). The fruit wall in that area becomes as if "cooked," whitish or straw-yellow, sunken, and papery to the touch. Over time, secondary fungi, for example, from the genus Alternaria, may settle on the damaged area, worsening the lesion (Bosland and Votava, 2012; Kemble et al., 2022).

Why Does This Happen?

Sunscald is a result of photooxidative damage. The process develops when two factors act on the fruit simultaneously:

1. Intense Sunlight. The light energy absorbed by the chlorophyll in the fruit skin, under certain conditions, triggers the formation of reactive oxygen species (free radicals) that destroy cell membranes (Rabinowitch and Sklan, 1981).

2. High Temperature of the Fruit Tissue. Sunlight heats the fruit's surface. If the temperature rises above a certain threshold (for pepper, this is about 38-40 °C), the cells are damaged (Rabinowitch et al., 1986; Barber and Sharpe, 1971).

It is important to note that this is not just a heat burn. If a fruit is heated in the dark, it will become soft and brown, but it will not turn white. The whiteness is precisely the result of the action of light against the background of heating (Rabinowitch and Sklan, 1981).

Which Fruits are Most Susceptible?

The susceptibility to sunscald strongly depends on the fruit's ripening stage:

• Most Vulnerable: Fruits at the stage of technical maturity (green, but already fully formed) and fruits that are just starting to color (at the "chocolate" stage, when green chlorophyll and red carotenoids are both present) (Wien and Stützel, 2020; Rabinowitch and Sklan, 1981).
• Less Vulnerable: Completely immature, small green fruits.
• Least Vulnerable: Fully ripe red fruits. They contain little chlorophyll, so the photooxidation process does not start (Rabinowitch and Sklan, 1981).

Large-fruited varieties with thick walls (e.g., bell peppers) are affected more often than small-fruited hot peppers, whose fruits often hang downwards and are shielded by foliage (Bosland and Votava, 2012).

Prevention – Protection from the Sun

Sunscald is easier to prevent than to cure. Affected fruits do not recover. Here are the main strategies:

1. Ensure Sufficient Leaf Mass. This is the most important factor. Foliage naturally shades the fruits. Avoid excessive pruning and do not remove excess foliage, especially in hot weather. Varieties that form dense bushes produce fruits protected from direct sun (Wien and Stützel, 2020).

2. Use Shade Nets. In regions with hot, sunny climates, this is one of the most effective methods. Light shading (by 25-36%) significantly reduces the risk of sunscald without greatly affecting yield. In the Negev Desert (Israel), shading reduced the percentage of damaged fruits from 36% to 2% (Rylski and Spigelman, 1986). This is particularly relevant for greenhouse cultivation or in southern regions.

3. Proper Cultivation Practices. Avoid defoliation (leaf loss) during periods of active sun. If you remove diseased or old leaves, do so in a way that does not expose the fruits. Also, avoid stresses that can lead to leaf loss (e.g., drought or diseases).

4. Variety Selection. When possible, choose varieties that naturally have dense foliage covering the fruits or a compact plant habit.

An Interesting Fact: "Hardening" of Fruits

Research shows that peppers can adapt to the sun. If fruits are subjected to preconditioning heat (e.g., kept for 6 hours at 40 °C in the dark), their resistance to sunscald in the following 15-36 hours increases significantly (Rabinowitch et al., 1986). This phenomenon is related to an increase in the activity of enzymes that protect cells from oxidative stress. This method is difficult to apply in practice, but it explains why plants that have grown in the sun since their youth suffer less from sunscald than those transplanted from a shady nursery directly into the blazing sun.

Remember: sunscald is not a disease but a signal that the fruit was not protected from the aggressive environmental impact. By helping the plant create natural "shade" with its leaves or using cultural practices, you will preserve not only the appearance but also the quality of the fruits.

---

Article Title for the Series: When Peppers Get Sick Without Diseases: How Weather, Watering, and Nutrition Affect Your Harvest.

Chapter Title: Chapter 4. Fruit Cracking: When the Pepper "Bursts" from Excess Water.

---

What does it look like?

Cracking can manifest in different ways:

• Concentric cracks (ring-like) – appear around the stem attachment.
• Longitudinal cracks – run along the fruit from the stem to the tip or along the sides.
• A network of fine cracks (russeting) – especially common in varieties like 'Jalapeño' and can be a varietal characteristic, especially in ripe fruits (Bosland and Votava, 2012; Rylski et al., 1994).

Cracks can be superficial (affecting only the skin) or deep (penetrating into the flesh). Deep cracks make the fruit unsuitable for long-term storage and for the fresh market.

The Main Cause – Pressure Surges Inside the Fruit

The primary cause of cracking is uneven water supply (Somos, 1984; Rylski et al., 1994). The mechanism of this process is as follows:

1. Fruit Growth. The pepper fruit grows by accumulating water in its cells. Its wall has a certain elasticity.

2. Humidity Fluctuations. When after a prolonged drought, or simply as a result of heavy watering (or rain), the plant receives a large amount of water, the roots start actively pumping it into the fruits. The fruit cells quickly fill with water, creating high turgor pressure from the inside.

3. Wall Rupture. If the fruit skin cannot stretch quickly enough or has already lost its elasticity (e.g., in ripening fruits), it cannot withstand the internal pressure and bursts.

Imagine a balloon: if you inflate it too quickly or if it is already inflated to its limit, it will burst. The same happens with a pepper.

What Factors Trigger Cracking?

1. Uneven Watering. This is the main trigger. A prolonged drought followed by heavy watering is the surest way to get cracked fruits. A fruit that grew in water-deficit conditions "gets used" to a smaller volume, and when water becomes abundant, its wall cannot withstand the sudden filling.

2. High Air Humidity. Especially at night, combined with low temperatures. Under such conditions, evaporation from the fruit surface is minimal, and all incoming water stays inside, increasing pressure (Rylski et al., 1994). This is particularly relevant for greenhouses and polytunnels.

3. Day/Night Temperature Fluctuations. Sharp temperature swings can also affect turgor and cell wall elasticity, making them more brittle.

4. Thin-Skinned Varieties. Varieties with thin skins are more prone to cracking than thick-skinned ones. For example, some sweet varieties with thin walls are more vulnerable than those intended for long storage.

5. Ripening Stage. Fruits at the stage of technical or biological maturity, when their growth is almost complete and the walls become less elastic, are most prone to cracking.

Prevention – Smoothness and Uniformity

Preventing cracking is possible, and the main strategy is to avoid sharp changes in growing conditions.

1. Regular and Uniform Watering. This is the most important rule. Water your peppers regularly, avoiding long periods of soil drying out. It is better to water more frequently with smaller amounts than rarely and very heavily. Keep the soil moist but not waterlogged. Use drip irrigation to ensure a uniform water supply.

2. Mulching. Mulch (straw, grass, agrotextile) helps retain soil moisture, preventing rapid drying and reducing the risk of sharp moisture fluctuations.

3. Rain Protection. In regions with frequent and heavy rainfall, especially during fruit ripening, it is advisable to use covers (tunnels, canopies, greenhouses) to protect against overwatering following a drought.

4. Humidity Control in the Greenhouse. In protected cultivation, it is important to maintain a stable humidity level, especially at night. Ventilate the greenhouse to prevent excessive air humidity.

5. Variety Selection. When possible, choose varieties with thick, strong walls that are resistant to cracking.

What to Do if Cracks Already Appear?

If you notice cracks, it's important to understand that the fruit will not recover. However, you can prevent cracks from appearing on other fruits:

1. Immediately Adjust Watering. If the soil has dried out, moisten it gradually, in small amounts, to avoid creating a sharp increase in humidity.

2. Harvest Damaged Fruits. Cracked fruits should be harvested and used for food first (e.g., for salads or processing), as they will not store well. Leaving them on the plant is not advisable – they can become a source of infection for healthy fruits.

Cracking is a disorder that is easier to prevent than to fix. Your main task is to create the most stable and predictable conditions for the plants, especially during the period of active growth and fruit ripening. And remember: sometimes slight cracking is simply the price for a juicy and tasty harvest, especially in some varieties.

---

Article Title for the Series: When Peppers Get Sick Without Diseases: How Weather, Watering, and Nutrition Affect Your Harvest.

Chapter Title: Chapter 5. Flower and Fruit Drop: When the Pepper "Changes Its Mind" About Fruiting.

---

What does it look like?

Abscission can affect different stages of reproductive organ development:

• Very small buds (less than 2.5 mm in diameter).
• Bud ready to open (large but still unopened).
• Open flowers.
• Young fruitlets (within the first week after pollination and up to 14 days after) (Wien et al., 1989a; Wubs et al., 2009).

In severe cases, under strong stress, the plant may shed all flowers and fruitlets. Gardeners sometimes describe this condition as "the plant has gone vegetative"—it stops flowering and starts actively increasing its green mass (Wien and Stützel, 2020).

Why Does This Happen?

Flower and fruit drop is a complex process triggered by several factors, but at its core is the competition for assimilates (products of photosynthesis, primarily sugars) (Marcelis et al., 2004; Wubs et al., 2009; Wien and Stützel, 2020).

The plant is a single system. When it already has actively growing fruits on it (especially about 3 weeks after setting), they become the main "consumers" of the sugars produced by the leaves. All other reproductive organs (flowers and young fruitlets) find themselves in a nutrient deficit. To avoid wasting resources, the plant initiates their abscission.

Once the fruits reach maturity and their demand for assimilates decreases, flowering and fruit set resume. Thus, peppers often show a cyclical fruiting pattern: a wave of fruiting is followed by a pause, and then the next wave (Wien et al., 1989a; Hall, 1977).

What Factors Trigger Mass Abscission?

Any factor that reduces the plant's ability to produce assimilates (light, carbon dioxide) or increases their consumption (fruit growth, stress) can trigger abscission.

1. High Temperature. This is the main cause of flower and fruit drop in peppers. At high daytime (above 32 °C) and especially nighttime (above 21 °C) temperatures, the plant spends too much energy on respiration, and there is simply not enough carbohydrates for the flowers. Additionally, high temperatures can directly damage pollen, making it sterile (Wien and Stützel, 2020; Aloni et al., 1991; Rylski and Spigelman, 1982). In fact, even at 32/15 °C (day/night), many varieties show complete flower drop (Wien, 1990).

2. Low Light Intensity. In cloudy weather or in greenhouses during winter, photosynthesis slows down, and the plant cannot produce enough sugars to sustain all flowers and fruitlets (Wien et al., 1989b; Bakker, 1989).

3. Water Deficit. Drought, especially combined with high temperatures, sharply limits water and nutrient uptake, affecting all processes, including photosynthesis and assimilate transport (Wien and Stützel, 2020).

4. Presence of Actively Growing Fruits. As mentioned, competition for assimilates is a natural mechanism. If there are already several large fruits on the plant, new flowers and fruitlets will be shed until these fruits mature.

5. Nutrient Deficiency. Although excess nitrogen is often mistakenly blamed for abscission, it is more of a consequence than a cause. However, balanced nutrition, especially sufficient phosphorus and potassium, is important for normal flowering and fruit set.

The Mechanism of Abscission: Hormonal Imbalance

At the physiological level, flower and fruit abscission is regulated by hormones. Under stress (heat, low light), in the flowers and fruitlets:

1. Auxin (IAA) levels decrease – a hormone that suppresses the formation of the abscission layer.

2. Sensitivity to ethylene increases – a hormone that, on the contrary, stimulates the formation of the abscission layer at the base of the flower or fruit, leading to its drop (Wien et al., 1993b; Huberman et al., 1997).

Simply put, the plant essentially "gives the command" to drop the flower when its resources become insufficient.

Prevention: How to Help the Plant Retain Flowers

1. Select Tolerant Varieties. This is the most reliable method. Some varieties, especially hybrids for greenhouses, are genetically more resistant to flower drop. They are distinguished by a better ability to distribute assimilates between fruits and reproductive organs (Wien et al., 1993b; Turner and Wien, 1994a; Elkind et al., 2008). When choosing a variety for hot climates, opt for those recommended for such conditions.

2. Temperature Control. In hot weather, use shade nets to reduce the temperature around the plants. In greenhouses, ensure good ventilation.

3. Regular Watering. Do not allow the soil to dry out, especially during the flowering period. Drought stress at this time is particularly critical (Wien and Stützel, 2020). Even a short-term water deficit can lead to mass abscission.

4. Carbon Dioxide (CO2) Supplementation. In greenhouses, increasing the CO2 concentration to 800-1000 ppm stimulates photosynthesis and increases sugar production, helping the plant "feed" more flowers and fruitlets (Nederhoff and van Uffelen, 1988).

5. Optimal Nutrition. Do not overfeed plants with nitrogen during the flowering period to avoid provoking excessive vegetative growth at the expense of fruiting. Ensure adequate phosphorus and potassium supply.

6. Crop Load Management. Although it sounds paradoxical, if you see that the plant already has many fruit sets and new flowers are dropping en masse, you can remove a few of the smallest fruitlets. This will reduce competition for resources, and the remaining fruits will get more nutrients, and new flowers will be able to set.

What to Do if Abscission Has Already Started?

1. Assess the Conditions. Check the temperature and soil moisture. If it's hot, shade the plants; if it's dry, water them.

2. Spray with a Micronutrient Solution. Foliar feeding with a complex fertilizer containing micronutrients (especially boron and zinc) can help reduce stress and stimulate fruit set.

3. Apply Plant Growth Regulators. In commercial vegetable growing, gibberellin-based preparations or ethylene synthesis inhibitors (e.g., silver) are used to reduce abscission. However, for amateur gardeners, such methods are usually unavailable and difficult to apply. The most reliable way is to create optimal conditions.

Remember: flower and fruit drop is not a death sentence but a signal that the plant needs help. By understanding the cause and adjusting the conditions, you can significantly reduce losses and get a good harvest.

---

Article Title for the Series: When Peppers Get Sick Without Diseases: How Weather, Watering, and Nutrition Affect Your Harvest.

Chapter Title: Chapter 6. Growth Stunting: When the Pepper "Freezes" from Stress.

---

What does it look like?

Growth stunting can manifest in different ways:

• Slowed stem and root growth. The plant does not increase in size, or growth is very slow. New leaves do not appear or appear with long intervals.
• Change in leaf color. Leaves may become pale green (chlorosis) or acquire a purple tint (a sign of phosphorus deficiency, often associated with cold).
• Leaf thickening and roughness. Leaves become dense, rigid, almost "leathery" (Nilwik, 1981). This happens because cells don't grow, but their walls thicken.
• Reduction in leaf area. Young leaves grow small.
• Absence of new shoots and flowers. The plant stops branching and does not form flower buds.

Why Does This Happen?

Growth stunting is a protective mechanism. The plant "assesses" the conditions and, if they are unfavorable, suspends active processes to survive. Restoration of normal growth is possible only when the stress causes are eliminated.

Prevention – The Key to Health

Preventing growth stunting is much easier than forcing a plant to resume growth after prolonged stress.

1. Correct Planting Timing. Plant peppers only when the danger of frost has passed and the soil has warmed to 15 °C and above.

2. Healthy Planting Material. Use only healthy, high-quality seedlings grown under optimal conditions (Wien and Stützel, 2020).

3. Optimal Care. Provide plants with regular watering, balanced nutrition, and protection from extreme temperatures.

4. Mulching. Mulch is your best ally in maintaining stable conditions for the roots and retaining moisture.

What to Do if the Plant "Freezes"?

If you notice the pepper has stopped growing, don't panic. Here's what you can do:

1. Analyze the Conditions. Check the air and soil temperature, soil moisture, and the presence of pests on the roots.

2. Adjust Care. If it's cold—cover the plants. If it's hot—shade them. If it's dry—water them. If roots are damaged—water with a root stimulant solution.

3. Fertilize. Carry out a foliar feed with a complex fertilizer containing micronutrients (especially zinc, boron, manganese) to support the plant and stimulate growth.

4. Be Patient. Recovery from severe stress can take several days or even weeks. The main thing is to create the most favorable conditions possible and not worsen the stress.

Remember: growth stunting in peppers is always a signal that something is wrong with the growing conditions. Observe your plants carefully, analyze possible causes, and take action. Your task is to create conditions for the pepper that allow it to fully realize its genetic potential.

What does it look like?

Deformations can be very diverse, and each one "tells" a story about its cause.

1. Curvature, Deformity, Irregular Shape. The fruit may be twisted, bent, with outgrowths or, conversely, sunken areas. It may be asymmetrical—one side larger than the other.

2. Flattened, Flat Fruits. Especially common in sweet peppers. The fruit appears "pressed in" on the sides, with a reduced number of seed chambers.

3. Small, Underdeveloped Fruits. Fruits grow small, not reaching the typical size for the variety. They often have thin walls and few seeds.

4. Fruits with a "Tail." Sometimes the pistil column remains on the fruit tip, forming a characteristic pointed "nose." This is especially noticeable in sweet varieties, where the tip is normally blunt or sunken.

5. Deformation of the Blossom End. It may be sunken or, conversely, pointed, with a retained stigma.

Why Does This Happen?

The shape of the pepper fruit is largely determined in two phases:

1. Pre-Flowering Phase (Ovary Formation). The main features of the fruit shape are established even before the flower opens. During this period, cell division occurs in the ovary (Munting, 1974; Sandoval-Oliveros et al., 2017).

2. Post-Pollination Phase (Fruit Growth). After pollination and seed formation, cells begin to actively enlarge. At this time, seeds release hormones (auxins) that stimulate the growth of the pericarp (fruit wall).

Any deviation in these processes leads to deformation.

Prevention: How to Grow Straight Fruits

1. Ensure Good Pollination. This is the most important factor for obtaining straight, large fruits.

• Pollinating Insects. Attract bees and bumblebees to the garden. In greenhouses, use bumblebees (the most effective pollinator for peppers) or carry out manual pollination (gentle shaking of flowers, pollinating with a soft brush). In greenhouses without wind and insects, pollination can be insufficient (Wien and Stützel, 2020; Bosland and Votava, 2012).
• Avoid Stress During Flowering. Do not allow sharp temperature fluctuations, drought, or excess nitrogen.
• Control Temperature.
• In Spring protect plants from cold nights (covers, mulch).
• In Summer during heat, use shading, especially at midday, to reduce temperature and prevent pollen damage.
• Provide Stable Watering. Avoid prolonged drought, especially during flowering and early fruit set. This is critically important for pollination and initial fruit growth.
• Balanced Nutrition. Provide plants with adequate phosphorus and potassium. Excess nitrogen, especially during flowering, can stimulate vegetative growth at the expense of fruit set.
• Variety Selection. If your region often has cool springs or hot summers, choose varieties bred for such conditions and with good stress tolerance (Elkind et al., 2008). Some varieties are genetically more inclined to form straight fruits even under imperfect conditions.

What to Do if Deformation Has Already Occurred?

If you notice fruits starting to grow deformed, it's already impossible to correct them. However, you can prevent further deterioration.

1. Check the Conditions. Assess the temperature, soil moisture, and presence of pollinating insects.

2. Adjust Care. If you find a stress factor (cold, heat, drought), take measures to eliminate it (cover, shade, water).

3. Remove Severely Deformed Fruits. If a fruit is strongly twisted or ugly, it's better to remove it so the plant doesn't waste resources on it and instead directs them to forming new, higher-quality fruits.

4. Support the Plants. Carry out a foliar feed with a complex fertilizer containing micronutrients, especially boron (stimulates pollination) and potassium (improves fruit quality). This will help the plant survive stress and form better-quality fruits in the future.

A Special Case: Parthenocarpy (Fruit Set Without Seeds)

In peppers, parthenocarpy—fruit development without pollination and without seeds—sometimes occurs (Tiwari et al., 2011). This often happens at low temperatures (12-15 °C at night), when pollen is non-viable, but the ovary still begins to grow (Rylski and Spigelman, 1982; Polowick and Sawhney, 1985). Such fruits are usually small, with thin walls, irregular shape, often flattened. Even under good conditions, they cannot be "fixed"; they will remain small and ugly. Therefore, preventing poor pollination is not only about quantity but also about the quality of the harvest.

Practical Takeaways for the Gardener

• The beauty of pepper fruits begins with pollination. Your main task is to ensure the best possible conditions for this process.
• Temperature is the main enemy of correct shape. Avoid both cold and intense heat during flowering and early fruiting.
• Uniformity is the key to success. Stable conditions (watering, nutrition, absence of stress) are the key to forming beautiful, straight fruits.
• Choose the right varieties. For your region, select varieties that are well-adapted to the local climatic conditions.

Fruit deformation is not a disease but a signal that the plant experienced stress during the most critical period. By understanding the causes, you can minimize losses and achieve a harvest you can be proud of.