Why and what to do if eggplant leaves turn yellow and wither

An experienced gardener can glean a wealth of useful information about the health and needs of eggplant plants from their appearance. The condition of the leaves can be used to assess growing conditions, care errors, and nutritional issues, as well as to diagnose diseases and identify pest infestations.

One of the most common problems with eggplants is yellowing and wilting of leaves, which can occur due to several reasons.

Causes of yellow leaves

Yellowing of eggplant leaves can be a natural reaction to the stress the plant experiences when exposed to new conditions. If the leaves turn yellow shortly after being planted in a greenhouse, there's likely no cause for concern—the acclimation process will be complete in about two weeks, and the plants will return to their healthy appearance. In other cases, yellowing of the leaves is a symptom of pathological processes that require gardeners to take action to restore the plants' health.

Growing conditions

The condition of eggplant bushes and the future harvest largely depend on the quality of care and the availability of the necessary conditions for normal development. Yellowing and wilting of plant leaves can be caused by:

Incorrect watering

When water is insufficient, the plant doesn't send nutrients to the leaves, concentrating them in more important parts—the roots, stems, flowers, and fruits. In this case, the leaves turn yellow and wilt due to starvation. Wilting and leaf drop can also be the result of root rot due to overwatering or watering with cold water.

Unsuitable soil

This symptom can occur in eggplants growing in heavy, poor, and highly acidic soils. Peaty soils are the worst option. The plants prefer loose, well-aerated soils.

Suboptimal temperatures

Sudden temperature fluctuations and increases above 30°C are detrimental to eggplants. In both cases, the plant's leaves may turn yellow and lose their elasticity. Furthermore, eggplants are harmed by both dry and hot air, when high temperatures are caused by sunny, hot weather, and by excess humidity, when the temperature rise is due to insufficient ventilation in the greenhouse.

Poor lighting

Indoors, the plant often suffers from light deficiency. Yellowing leaves can also be a result of sunburn, including from phytolamps used to compensate for the lack of sunlight.

Diseases and pests

Pests and pathogens also affect the appearance of plants, including their foliage. Yellowing and wilting of eggplant leaves is a symptom of diseases such as:

Fusarium wilt

A fungal disease in which symptoms appear on the lower leaves. Fusarium attacks the interior of the plant, disrupting vascular function, preventing the distribution of nutrients throughout the tissues and causing toxicity. Most often, the disease results in the death of the plant, but in some cases, the plant may continue to grow (albeit slowly) and even produce a small number of small fruits. Fusarium is triggered by overwatering, increased soil acidity, and high temperatures (25–28°C).

Verticillium wilt

It typically appears during fruit formation. Initially, leaf segments on the lower tier of the bush turn yellow, followed by brown spots with a yellow border appearing on the leaf blades. The disease attacks the plant's blood vessels, impeding sap flow. The causative agent, a fungus, is activated by insufficient watering and temperatures around 16 to 20°C. The disease often occurs when excessive amounts of nitrogen are applied to the roots through organic fertilizer (manure is particularly dangerous).

Mosaic

A viral disease that often affects eggplants in greenhouses due to insufficient light. Another factor that triggers the disease is a drop in air temperature. Spots of lighter and darker shades of green appear on the leaves, which later turn yellow. The main consequence of the disease is stunted fruit growth. Ripe eggplants have woody flesh.

Among the pests that can attack eggplants, spider mites cause yellowing and wilting of leaves. Clusters of tiny parasites, visually resembling dust dusting the leaf blades, can be found on the undersides of lower leaves. If the mites have been present on the plants for a long time, webbing can also be seen entangling the leaf. In the initial stages of infestation, discolored spots appear at the insect's bites; later, the leaf becomes covered with light spots, curls, turns yellow, and wilts. The pest's activity causes stunted plant growth.

Nutritional deficiencies

Eggplants can react to a lack of nutrition in many elements by yellowing leaves, but most often the symptom indicates a deficiency of:

1. Nitrogen. In this case, the lower leaves on the bush turn yellow and wilt first. Nitrogen is responsible for distributing nutrients between plant parts; a deficiency disrupts the plant's metabolism. As a result, the leaves don't receive the necessary nutrition and wilt.
2. Potassium. In addition to yellowing leaves, deficiency manifests itself in poor flowering, drying leaf margins, and spotting of fruit.
3. Magnesium. The lower leaves lighten, acquiring a yellowish tint, while the veins on them retain a dark green hue.
4. Manganese. Signs of deficiency are similar to those of leaf mosaic disease.

Eliminating the problem of yellow leaves

Yellow leaves on eggplants are not a disease, but a symptom of a pathological process, so there are no general treatments. The underlying cause must be addressed and measures taken to mitigate its consequences.

Elimination of the consequences of violation of care

If the yellowing leaves are caused by improper gardening practices, in addition to correcting them, you need to support the plant's strength and help it cope with stress. In this case, one of the following foliar feedings is recommended:

• boron – dissolve 5 g of boric acid in a small amount of hot water (+50…+55°C), after dissolution dilute with 10 liters of cold water;
• yeast - dissolve 10 g of dry yeast in a bucket of warm water, let it sit for 2 days, before spraying dilute 1 part of the solution with 10 parts of water.

Treatment of diseases

Fusarium wilt spreads quickly through eggplant crops, so it's important to remove affected areas of the plant and all weeds from the area. Plant debris should be burned to prevent the fungus from spreading. Afterward, treat the crop with fungicides. Suitable fungicides include Fundazol, Benazol, and Consento.

Verticillium wilt is even more dangerous for eggplants; removing and burning affected plants is recommended. Other plants should be treated with Vitaros, Consento, Topsin-M, and Previkur.

Both diseases cannot be cured with folk remedies, but regular treatment of uninfected plants will help contain the spread of the fungus throughout the eggplant bed. The most effective folk remedies against fusarium and verticillium wilt are:

1. Whey. Dilute one part whey (sour milk) with an equal volume of water. Let it steep for 12 hours, then strain.
2. Yeast. Dissolve 100 g of fresh yeast and 100 g of sugar in 3 liters of warm water. Leave to ferment in a warm place for 2-3 days, stirring occasionally. Dilute the finished mixture with 10 parts water.

There are no effective antiviral medications, so tobacco mosaic control involves prevention and removal of diseased plants and weeds. It is recommended to treat healthy plants with whey.

Removing spider mites

When fighting spider mites, avoid using chemical insecticides whenever possible. For minor infestations, biological treatments such as Kraft, Bitoxibacillin, and Kleschevit can be used effectively. Folk remedies are also quite effective:

1. Onion peels. Pour 3 liters of boiling water over 500 g of peels. Let steep for 3 days, then strain before spraying.
2. Garlic. Crush the cloves from 3 heads of garlic and add 2 liters of hot water. Let it steep for 24 hours, then strain. Before using, dilute the infusion with 3 parts water.
3. Marigolds. A bucket of dried marigold flowers is filled with water and left in a dark place for 2 days.

In case of extensive pest infestation, only treatment with specialized products will help: Sanmite, Oberon, Actellic, Neoron, Confidor, Flumite.

Actions in case of nutritional deficiency

If eggplants are deficient in nutrients, foliar feeding is necessary. This method ensures that the plant receives the necessary elements as quickly as possible and eliminates any potential absorption issues due to soil or growing conditions.

Prevention

The main measure for preventing eggplant leaf yellowing is ensuring the plants are well cared for. Eggplants quickly react to gardener mistakes not only by yellowing leaves but also by dropping flowers and ovaries. The harvest can only be saved by providing the plants with all the necessary conditions.

Basic measures to prevent yellow leaves from appearing on eggplants:

• Since crop rotation is difficult in a greenhouse, it's important to renew the topsoil every few years. The soil for eggplants needs to be prepared: liming acidic soils and loosening heavy soils. Sand, rotted sawdust, and rotted manure can be used as loosening agents. Compost and sod should be added to peat soil. During the growing season, loosening the soil is very beneficial – this procedure not only provides oxygen to the roots but also reduces the risk of fungal diseases.
• To help young eggplant plants adapt better and more quickly after being transplanted into a greenhouse, harden off the seedlings. Plants should be transplanted to their new location with the root ball still attached, being careful not to damage the roots.
• Eggplants require regular and adequate soil moisture. During the initial growing season, plants are given 10 liters of water per square meter once a week, and during flowering, 12 liters per square meter twice a week.
• The difference between soil and irrigation water temperatures should not be too great, otherwise the eggplant's root system will be damaged and rot may occur. Watering with cold water also increases the risk of fungal diseases (anthracnose, powdery mildew, gray mold, copperhead, and others).
• In a glass greenhouse where plants are exposed to direct sunlight, or if supplemental lighting is used, avoid sprinkling eggplants to avoid burning. Evening watering is preferable.
• If temperatures are high, the greenhouse should be ventilated frequently. For cooling, place buckets of cold water between the rows, remembering to replace the heated water periodically.

• Fungal disease prevention is especially important for greenhouse eggplants. Pre-sowing seed treatment (for example, soaking the seeds in a potassium permanganate solution), soil disinfection for seedlings, and preventative plant treatments with folk remedies and biological preparations are recommended. Among the latter, Trichodermin is effective if applied to the planting holes in the greenhouse (but the soil temperature should not fall below 14°C; the preparation is most effective at 18°C). Ten days after planting the seedlings indoors, the first preventative fungicide spray can be applied. Zinc-based Antracol is suitable.

Yellowing leaves can be caused by a variety of factors, making diagnosis and treatment difficult. Once a disease or nutrient deficiency is detected, it's important to critically assess the growing conditions and ensure optimal conditions for the plants. Conversely, don't rush to fertilize if proper cultivation practices aren't followed—improving the conditions is key. This precaution will prevent overfeeding your eggplants.