Purple Pepper Leaves: Causes and Treatment

When growing peppers, some vegetable growers encounter the problem of leaves turning from green to purple. These plants lose their ability to absorb nutrients, become stunted, and stop producing fruit. Unusual spots can appear due to unfavorable conditions, diseases, or agricultural errors. To get rid of purple spots on leaves, ensure proper care, use special products, and apply fertilizer.

Causes of the problem

Before deciding what to do about purple pepper leaves, it's important to determine why they appeared. A bluish tint to the natural foliage coloration of peppers signals a phosphorus deficiency. Low average daily temperatures or watering errors can also cause the unusual tint. Most often, vegetable growers notice purple leaves when growing peppers in regions with a changeable, cool climate. In unfavorable conditions, they should carefully prepare the soil for planting and select cold-resistant varieties.

Temperature changes

Bell peppers don't tolerate sudden weather changes well. During severe cold snaps, their leaves often turn blue. After this, the leaf blades curl up and gradually dry out. Planting seedlings outdoors too early, before the soil has had time to warm up, can trigger these negative changes. The cold can cause the immature plant to become ill, and its leaves can turn blue.

Nutritional deficiencies

A nutrient imbalance in the soil is another cause of foliage discoloration in sweet peppers. Before transplanting the seedlings to their permanent location, prepare the soil with mineral and organic fertilizers. The vegetable prefers light, well-drained soil. To impart the desired qualities, sand is added to the soil in the garden bed. Loamy soil is not suitable for growing bell peppers.

The soil is too dry

Sweet peppers prefer to grow in well-drained soil. Insufficient water slows down metabolic processes in plant tissues. The leaves turn blue, then purple. If left untreated, the veins on the leaf blades become clearly visible. The foliage then curls and dries out.

Phosphorus deficiency

Vegetable growers typically pay close attention to the nitrogen content of the soil. It is applied through organic and mineral fertilizers. Phosphorus concentrations are a lesser concern. Garden beds are fertilized with eggshells or phosphorus fertilizers are neglected altogether. In areas where the soil is constantly being used and not left to rest, the plant's root system quickly absorbs phosphorus from the soil. When the concentration of this element becomes minimal, vegetable yields decline and susceptibility to disease increases.

Phosphorus fertilizers can be omitted if the soil is regularly enriched with a variety of organic matter and left fallow for 1-2 years. This allows normal phosphorus concentrations to be restored naturally. Otherwise, neglecting phosphorus fertilizers leads to poor harvests and weak plants in the garden.

With phosphorus deficiency, in addition to the purple tint of the leaves, the following changes occur:

• leaves and shoots grow deformed and underdeveloped;
• the bushes are significantly stunted;
• the root system does not develop;
• crop yields are declining;
• few seeds are formed in the fruits;
• the fruits grow small and irregular in shape;
• susceptibility to pathogens increases.

To avoid negative changes, phosphorus fertilizers should be applied promptly. This element is found in single and double superphosphate, ammonium hydrogen phosphate, bone meal, ammonium phosphate, thermophosphate, and precipitate. Wood ash also contains a small amount of phosphorus.

Anthocyanosis

With a persistent phosphorus deficiency, peppers develop anthocyanosis. This disease causes the plant to gradually wither and eventually die. The first sign of this disease is bluish leaves. The discoloration then spreads to the stems of the pepper plant. The leaf blades curl upward or toward the stem. If left untreated, anthocyanosis causes the stem to become covered in hairs and brittle. The disease spreads to the root system. The roots weaken, become thinner, and lose the ability to absorb nutrients.

Violation of crop rotation

Growing peppers continuously in the same area wastes soil resources. The plant's root system consumes nutrients essential for the vegetable's development. This disrupts the balance of beneficial elements. Pathogens and pests common to nightshade crops accumulate in the soil. Regular rotation of vegetable planting sites is recommended. Good precursor crops for peppers include legumes, melons, grains, or greens.

Treating peppers in a greenhouse

When growing peppers in a greenhouse, a favorable microclimate is maintained. Any deviation from acceptable air temperature standards, or a lack or excess of humidity, can cause the development of vegetable diseases. Drafts, sudden cold snaps, or extreme heat are detrimental to pepper plants.

Maintaining a stable temperature

To monitor the temperature inside the greenhouses, thermometers are installed and their readings are monitored daily. To ensure smooth changes in humidity and temperature, ventilation is provided in the room. This is done in the morning or late evening.

In addition to air temperature, soil warming is monitored. The acceptable range is between 14°C and 25°C. Lower temperatures can lead to phosphorus deficiency in pepper plants.

The following methods are used to regulate the air temperature inside the greenhouse:

1. At night, cover the plants with an additional layer of film. It is stretched so that there is at least 5 cm of space between it and the main cover. The resulting air cushion will protect the plants from the cold air outside the cover.
2. An additional cover is installed inside the greenhouse to limit the air volume above the pepper plants. Wooden or plastic arches are installed over the pepper plants and covered with 0.5 mm thick film. The cover is periodically removed for ventilation to prevent excessive temperature increases.
3. To further warm the soil, a mulch layer is applied. Film or spunbond is used for this. These materials warm the soil by 1-2 degrees.

Increase the air temperature in the greenhouse carefully. Too much and too quickly will cause leaf wilting and plant death.

Fertilization

To improve foliage, spray pepper plants with a copper sulfate solution. This solution has a disinfectant effect and acts as a fungicide. It normalizes metabolic processes and helps combat pests. To prepare the solution, dissolve 100 g of copper sulfate in 10 liters of warm water. This solution helps combat anthocyanosis. Plants begin to recover within 15 days of treatment.

To compensate for nutrient deficiencies in the soil, complex mineral-organic fertilizers are added. The plant root system easily absorbs them. superphosphatePeppers are fed with a solution of this preparation after the first shoots emerge. A second application is made 14 days after transplanting to their permanent location. The plants can be given a final superphosphate fertilizer at the flowering stage.

Organizing proper care

When growing bell peppers in a greenhouse, following proper agricultural practices can help avoid many problems. Proper care includes the following procedures:

• regular watering of pepper bushes with a moderate amount of water;
• fertilizing plants after moving them to a permanent location, before flowering and at the stage of fruit formation;
• maintaining optimal temperature;
• protection from drafts and regular ventilation;
• regular inspection of plants to detect signs of disease;
• loosening the surface layer of soil after watering;
• spraying bushes to prevent diseases and pest attacks.

Treating peppers in open ground

When peppers are grown in unprotected beds, purple leaf turn occurs less frequently. The causes of the disease are cold weather and phosphorus deficiency in the soil. Without additional protection, open-ground plants are more susceptible to inclement weather. Therefore, transplanting to unprotected beds is done 15-20 days later than in a greenhouse. Plants are being transplanted after the final establishment of warm weather, when the threat of recurrent frosts has passed.

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Organizing additional shelter

If the weather forecast predicts a sharp drop in temperature, pepper beds in the garden are covered. Polyethylene, spunbond, or agrofibre are used for temporary cover. To protect the root system, the surface soil layer is mulched with sawdust.

Proper watering

Bell peppers don't tolerate lack of moisture well. Plant growth slows, and over time, they begin to wilt. Peppers should be watered regularly, ensuring the soil is well-moistened. After watering, the soil should be loosened to slow moisture evaporation and improve air circulation to the roots. Water sparingly to prevent excess water from pooling around the roots.

Application of fertilizers

For open-ground plants, you can use organic matter weekly as a fertilizer:

1. When dry, the soil is enriched with a mixture of humus, rotted manure, sand and wood ash.
2. A mullein solution is used as a root fertilizer. It is prepared by mixing cow manure with water in a ratio of 1:15. The liquid is poured under the roots, avoiding contact with the leaves.

Mineral fertilizers can be used, including superphosphate, urea, and Agricola. For foliar spraying, use a solution of 10 liters of water and 10 ml of brilliant green. This type of fertilizer improves plant resistance to disease.

Organization of feeding

The soil is enriched with nutrients before planting the plants in their permanent location. To prepare the soil, while digging the bed, add 200 g of wood ash, 10 liters of compost, 1 teaspoon of potassium salt, and 1 tablespoon of superphosphate per 1 m².

Repeated top dressing is carried out Three weeks after transplanting the seedlings to their permanent location. To prevent the foliage from turning purple, use fertilizers containing increased amounts of phosphorus from this time on. Before applying the fertilizer, water the soil with warm water. Then, pour a solution of 10 liters of water, 15 g of urea, and 3 g of superphosphate under each plant.

During the active growth stage, apply fertilizers containing nitrogen, calcium, and phosphorus 2-3 times per month. Before flowering, water the bushes with a complex mineral fertilizer to stimulate flowering. Prepare and use the solution according to the package instructions.

If plants are severely deficient in phosphorus, fertilize with a concentrated superphosphate solution. To prepare it, add 200 g of fertilizer to 1 liter of hot water and let it steep for 12 hours. Then, bring the volume up to 10 liters. Pour 1 liter of the prepared solution under each plant.

Prevention

Proper soil preparation for planting helps prevent phosphorus deficiency and the development of anthocyanosis in peppers. This is accomplished by enriching the soil with superphosphate. Organic and other mineral fertilizers are also added. Garden beds are organized according to crop rotation requirements. Peppers should not be planted in areas previously occupied by other nightshade crops.

The grown seedlings are moved to their permanent location within the recommended timeframe. They are planted in open beds only after warm weather has fully set in and the soil has warmed. If cold weather threatens, cover the plants with protective material. Temperatures in the greenhouse are monitored. If necessary, provide additional insulation or reduce air heating through ventilation.

A change in the color of pepper leaves and the appearance of a purple tint indicates improper care or the onset of a disease. Once the cause is identified, the plants can be restored to health by insulating them or fertilizing them with mineral and organic fertilizers.