Agrotechnical and plant protection features for pepper and eggplant in protected soil

Agrotechnology of pepper and eggplant in a greenhouse

Pepper is usually grown after lettuce, celery, or early tomatoes in peat bags or in soil. Specific soil disinfection for this crop is not carried out separately; the procedure is included in the general cycle of greenhouse work after harvesting">harvesting. Pepper transplants are grown in soil or peat composts by sowing seed from December to April.

Optimal temperature for seed germination of pepper is 24 °C, which allows for pricking out seedlings after 12–14 days. After transplanting into pots, the temperature is maintained within 18–23 °C at maximum air humidity. During the growing of transplants and the crop itself, the air is enriched with carbon dioxide to a concentration of 0.1 g/L. Pepper transplants are moved to their permanent location upon the appearance of the first flower buds. To help the plants establish faster, the temperature in the first few days after planting can be increased slightly.

Agrotechnology for eggplant is largely similar to the rules for growing pepper. Eggplant seeds germinate at a temperature of 20 °C. To protect against verticillium wilt, plants are often grafted onto resistant tomato rootstocks. Supplemental lighting in nurseries significantly accelerates the growth of young eggplant plants. After transplanting into soil, the crop is provided with a regulated temperature regime depending on the developmental phase. Feeding area and planting density for eggplant remain the same as for pepper.

• Planting density — 20–25 thousand plants/ha
• Feeding area — 35x45 cm
• Yield of late pepper — 150–200 t/ha
• Time until pepper pricking out — 12–14 days

Control of root rots and gray mold

Damping-off, crown rot, and root rots are caused by soil pathogens Pythium spp. and Phytophthora spp. On young seedlings, the disease manifests as a characteristic constriction of the stem at the soil surface. At later stages of seedling development, fungi cause browning of the roots and wet brown rot of the root neck. The disease affects plantings under poor drainage conditions when the soil remains waterlogged for a long time.

1. Grow seedlings only in previously disinfected soil or compost.
2. Incorporate etridiazole into the compost before sowing seeds if soil is used in its composition.
3. Water the seedlings with solutions of zineb and etridiazole after their emergence to protect against root rots.

Gray mold is considered the most common and damaging disease of pepper in protected ground. The fungus infects leaves and stems, penetrating through mechanical wounds or dying plant residues. A girdling stem lesion quickly leads to the wilting of individual shoots. The infection often establishes itself on fallen flower parts stuck in the branch forks.

The development of gray mold is promoted by high air humidity and dense planting, which creates a favorable microclimate. Spore dispersal occurs mechanically during maintenance work. To contain the pathogen, it is necessary to combine microclimate regulation with chemical treatments. In unheated greenhouses, where controlling humidity is more difficult, it is recommended to remove lower leaves and increase ventilation.

When necessary, plantings are treated with fungicides using the high-volume spraying method. Benzimidazoles, thiram, and iprodione show the highest efficacy. Since these products have mainly a protective action, it is crucial to ensure maximum coverage of leaves and stems with the working solution, especially within the plant canopy.

This disease is common in Southern European countries, affecting not only pepper, but also cucumber and tomato. Symptoms of the infection include chlorotic spotting and mottling on the upper side of the leaves, and spots with a felt-like coating of conidiophores and fungal conidia on the underside. Conidia germinate in low humidity; on moistened leaves, the development of the disease weakens.

Control. Data on the efficacy of fungicides against powdery mildew on pepper are scarce. Thiophanate-methyl provides satisfactory results. Apparently, the same preparations can be used on pepper as those used for the control of powdery mildew on cucumber (see page 201).

Irrigation by overhead sprinkling, which moistens the leaf surface, appears to prevent outbreaks of powdery mildew.

Tobacco mosaic virus, TMV (Nicotiana virus 1)

Pepper can be infected by various strains of the tobacco mosaic virus. Many pepper cultivars, including Bellboy, are resistant to the tomato strain of TMV, but a form pathogenic to most cultivars has recently been discovered on pepper. The tomato strain of TMV causes very serious damage to susceptible pepper cultivars, such as Sweet Spanish Yellow and Sweet Spanish Red. The first symptom of infection is necrosis along the main leaf vein, followed by wilting and gradual defoliation (Fig. 10.3). The plant does not die; lateral buds give rise to new shoots, on which, however, mild mosaic symptoms also appear. The form of TMV pathogenic to pepper does not cause necrosis or leaf drop, but a mild mosaic is visible on the leaves and fruits of infected plants. In addition, fruit deformation begins; they become wrinkled and develop necroses.

Both forms of the virus can be soil-borne and survive for a long time in infected root residues in the soil. The form affecting pepper is sometimes transmitted via seed as well. Tomato crops located next to pepper serve as a source of infection for it (tomato form of TMV), although most tomato cultivars are resistant to this virus and mosaic is rarely encountered on them.

Control. TMV is one of the most virulent plant pathogenic viruses, and once the disease appears on individual plants, the infection spreads rapidly throughout the crop. Even touching infected plants while walking in the greenhouse or performing maintenance work is sufficient to spread the pathogen. Infected plants must be isolated at the first sign of their detection, and work should always be started moving towards them. Removing infected plants is pointless, as if they have appeared in the planting, the spread of the pathogen has already occurred, and after culling, infected but asymptomatic plants will remain in the crop anyway.

To sanitize seed infected with TMV, steam treatment, acid treatment, or seed treatment in a trisodium orthophosphate solution can be used (see the section on tomato mosaic control, p. 172). Spraying with a solution of dry milk leads to a reduction in the rate of spread of the virus form affecting pepper.

Blossom-end rot of fruit (rot of the floral end of the branch)

This disease is similar to that occurring on tomato (see p. 183). A black, dry spot appears on the fruit at the point of peduncle attachment; on a cross-section, necroses of the fruit wall and some seeds are visible. Sometimes the symptoms are not visually apparent, with the necrosis affecting only a small part of the fruit wall and some seeds.

Blossom-end rot most often affects well-developed plants with vigorous foliage. If, during the fruit ripening phase, the plant experiences a lack of moisture or water loss through the leaves occurs more actively than its uptake by the roots, blossom-end rot also develops.

The most common causes of the disease:

• lack of water, especially when combined with periods of increased transpiration;
• calcium deficiency.

Calcium deficiency also causes symptoms of blossom-end rot, and in extreme conditions, the incidence in peppers can be reduced by performing spraying with a calcium nitrate solution.