How to combat white rot on eggplants

Symptoms of white rot in eggplants appear throughout the entire surface of the plant, with infection occurring through the roots. The disease can occur in any growing conditions, in any region, as the fungus thrives in conditions of overwatering, which depends not only on poor watering but also on weather conditions.

What are the signs of the disease and how can it be treated in eggplants?

Symptoms and causes of white rot on eggplants

Sclerotinia wilt, or white rot, is a disease caused by polyphagous fungi that live and overwinter in the soil and on plant debris. Spores survive on seeds collected from infected crops. In the soil, the fungus can survive for up to 8, and sometimes up to 10, years. Spores are germinate in cool, humid conditions.

As the fungus develops, it forms a mycelium, which appears as a white coating on certain parts of the eggplant bush, followed by the formation of sclerotia and spores. Plants become infected from spores and small mycelial particles, which are carried by wind, rain, and insects. The disease is often focal.

External manifestations of the disease

Irregular lesions with a whitish, cotton-like coating appear on eggplant stems, with lumps (sclerotia) forming within them. These lesions gradually soften, disrupting the plant's root supply, causing the plant to wither and dry out.

The disease appears on leaves, and rarely on fruit, as dark, wet spots. The fruit itself absorbs water, first becoming soft, then slimy, and large white spots form on the surface. In the final stages of infection, the fruit becomes covered with black lumps (sclerotia).

Causes of white rot in eggplants

In greenhouses, following planting and cultivation guidelines is often sufficient to protect eggplants from all pests. In open ground, plants are constantly exposed to external weather conditions. Reasons why eggplants can become infected with sclerotinia include:

• frequent rains, high soil and air humidity;
• improper watering, use of cold water;
• failure to comply with recommended planting patterns (thickening).

Particular attention should be paid to eggplant beds if white rot has appeared on neighboring crops. The fungus spreads very quickly, and delayed treatment will lead to an epidemic. Fruit affected by sclerotinia is unsuitable for storage in the same container as healthy ones. The spores (sclerotia) of the fungus will quickly spread throughout the fruit, destroying the entire harvest.

Prevention and treatment of white rot in eggplants

The best protection for plants against various diseases is proper care. Adherence to proper agricultural practices is the key to preventing all kinds of illnesses. What measures can help protect eggplants from white rot?

1. Eggplants should be planted only when the weather is consistently warm (18–20°C during the day). During periods of high risk, such as when a sudden, significant cold snap threatens, the beds should be covered. The soil in the eggplant plot should be loose and permeable; heavy soils must be structured, and reliable drainage is recommended.
2. Eggplants are planted in the same spot every four years. The best predecessors for this crop are cucumbers, early cabbage, and onions, while the worst are potatoes, peppers, and tomatoes.
3. If the plants in the designated area (outdoors) suffered from white rot last season, the soil should be disinfected before planting the eggplants. In a greenhouse, the soil can be replaced.
4. Eggplants should be watered at the roots, not the leaves. It's even better to create furrows (along the beds) for watering. Before flowering, eggplants should be watered once a week; during flowering, fruiting, and drought, water them twice every seven days. Use only warm water. After each watering or after rain, gently loosen the soil to ensure the roots receive sufficient oxygen.
5. In the greenhouse, the air humidity should not exceed 70%; after watering, the room is ventilated.

If rainy periods accompanied by low temperatures are common in the region, planting resistant eggplant varieties is a good preventative against fungal diseases:

• Epic F1;
• Diamond;
• Black beauty;
• Faith;
• Bibo F1;
• Albatross;
• Graffiti;
• Quartet;
• Robin Hood;
• Valentina F1.

When choosing a variety, be sure to consult with the seller or browse forums to find varieties suitable for your area, and choose fungus-resistant ones. Purchase seeds only from trusted, reliable producers.

How to disinfect soil

The white rot pathogen that causes eggplant disease is very resilient, and beds where outbreaks have occurred remain potentially dangerous, even with timely treatment. Replacing the soil is a labor-intensive task, but another option is to treat the soil. We'll describe two ways to solve this problem.

Biopreparations

It's best not to use chemicals in small areas or greenhouses. Instead, use products containing microorganisms that destroy fungi and are harmless to humans, soil organisms, animals, and insects. Baikal EM-1 and EM-5 are the most effective. They are applied in the fall 15-20 days before the first frost. In the spring, when the soil has warmed slightly, the procedure is repeated.

Other biological products that produce good results include Baktofit, Trichodermin, Planzir, Alirin B, Fitocide, Fitosporin, Flora-S, and Fitop-Flora-S. These products should be applied in the fall and spring under shallow (5-10 cm) tillage. To determine the application rate for any product, be sure to read the instructions or consult the retailer.

Chemicals

For chemical soil disinfection, purchase products classified as hazard class 3 or 4. After treatment, it's best to take a break and leave the area unused for one season, as chemicals kill not only fungi but also beneficial microflora. Even with regular fertilization, plants may experience poor growth.

After harvesting vegetables and removing plant debris, the soil can be treated with a 3% Bordeaux mixture solution. In the spring, when warm, dry weather sets in, a 4% copper oxychloride solution or a 2% Oxychom solution is applied to the soil to a depth of 15 cm. Recommendations regarding the amount of solution per square meter are provided on the product packaging.

How to cure eggplants from white rot

When the first signs of sclerotinia leaf spot are detected on eggplants, all affected parts of the plant should be cut off. Any mechanical damage is a gateway for infection; all wounds should be immediately treated with crushed chalk or wood ash. It's a good idea to spread peat over the soil surface and increase watering. If it rains during this period, ensure drainage and loosen the soil whenever possible. To support the plant, you can feed it with complex mineral fertilizers.

In the early stages, spraying with a copper sulfate solution (2 grams per liter of water) or 1% Bordeaux mixture will help stop the fungus from developing. Two to three treatments, spaced 7 to 14 days apart, may be necessary, depending on weather conditions. The bushes should be thoroughly moistened, applying the solution to the undersides of the leaves.

Other copper-containing products can also be used, and alternating treatments is a good idea. In advanced cases, eggplants cannot be treated; the plants are discarded and the soil is disinfected.

The same biological products used for soil disinfection are suitable for eliminating white rot on eggplants. However, it's important to remember that the treatment process with these products is quite lengthy, so they are best used for preventative purposes (systematic treatments from planting until the beginning or end of harvest).

Finally, a few tips. Since young eggplant plants are most susceptible to white rot, handle the seedlings with extreme care. Any damage will inevitably lead to fungal infection. When collecting seeds yourself, be sure to carry out pre-sowing preparation (disinfection and sorting). Before applying any soil treatments, it's a good idea to irrigate the seedbeds with boiling water. Heat treatment often kills up to 30% of the spores.