What are the symptoms of Verticillium wilt in eggplant, and how is it prevented and controlled?

In recent years, with the adjustment of the rural industrial structure, in some areas, due to many years of continuous cropping, soil pathogens have increased year by year, and the occurrence of Verticillium wilt in eggplant has become increasingly serious, affecting the yield and quality of eggplant and becoming one of the obstacle factors in eggplant production. So, what symptoms does Verticillium wilt in eggplant have? What control measures are there?

1. What is Verticillium wilt in eggplant?

Verticillium wilt in eggplant, also known as half-side madness, black heart disease, and wilt disease, is an important disease harming eggplant. Eggplant can be infected at the seedling stage, and symptoms mostly appear in the field after fruit set.

The pathogen of Verticillium wilt in eggplant is Verticillium dahliae. It belongs to the genus Verticillium in the subdivision Deuteromycotina. On the culture medium, the pathogen first grows white mycelium, then forms a large number of black sclerotia. Conidiophores branch in whorls, with 3 to 4 branches per whorl; conidia are colorless, single-celled, and long ovoid. The optimum temperature for pathogen growth is 22.5°C, and it can still grow under culture conditions at 30°C. The optimum pH for growth is 5, 3 7, 2, and under pH 3, 6 conditions, it grows well. The pathogen has a relatively wide host range. In addition to harming eggplant, it also harms more than 180 species of plants in 38 families, including Solanaceae vegetables such as pepper, tomato, and potato, as well as cucurbit crops.

2. What symptoms does Verticillium wilt in eggplant have?

The disease mostly begins after the first fruit sets. On one side of the plant, the lower leaves turn yellow near the petiole at the leaf margin and between the veins, gradually developing into half a leaf or the entire leaf turning yellow, with the leaf margin curling slightly upward. Sometimes the lesion is limited to half a leaf, causing the leaf to become distorted. On sunny days with high temperature, diseased plants wilt, and can recover at night or on cloudy and rainy days. When the disease develops rapidly, the entire leaf often becomes yellow and wilted, turns brown, and dies.

3. Control measures for Verticillium wilt in eggplant

1. Choose disease-resistant varieties, such as Long Eggplant No. 1, Longzha Eggplant No. 1, etc. Select disease-free good seeds, which can be collected from disease-free fields or selected from disease-free areas. Before sowing, seed disinfection treatment should be carried out. Seeds can be soaked in warm water at 55°C for 20 to 30 min; or treated with 70% quintozene powder at 0.2% of seed weight.

2. Raise seedlings in disease-free soil or disinfect seedbed soil. The seedbed should be selected in a plot with high and dry terrain, convenient drainage, fertile soil, and no pathogens. Before sowing, the seedbed soil should be fully turned and sun-dried, with sufficient decomposed compost applied, and disinfected with 50% carbendazim wettable powder or 70% quintozene at 8 to 10 g per sq m.

3. Implement crop rotation. Rotate with rice for 1 to 2 years, and rotate with non-Solanaceae vegetables for 4 to 5 years.

4. Use plug tray seedling raising. One plant per plug cell. The plants are evenly distributed, the nutrient soil has sufficient nutrients and good permeability, so the seedlings are sturdy and the root system is well developed; when lifting seedlings for transplanting, roots are generally not damaged or only slightly damaged, and there is no seedling recovery period after planting, which enhances disease resistance.

5. Apply grafting seedling technology. According to systematic observation and records, grafted eggplant seedlings have strong resistance to Verticillium wilt, and the disease incidence can be reduced by 4.7% to 34.5%.

6. Apply decomposed organic fertilizer, and topdress with mixed nitrogen, phosphorus, and potassium fertilizer, and carry out timely intertillage and hilling to promote root growth.

7. When diseased plants are found, they should be removed promptly and taken out of the vegetable field to be deeply buried or burned.

8. Chemical control. At transplanting, use 5 kg of 50% carbendazim wettable powder per mu mixed with 100 kg of fine soil to make medicinal soil, and spread it in the transplanting holes as preventive treatment. After transplanting, spray the roots and ground with 70% dexon wettable powder 500 times solution, 50% benomyl wettable powder 1000 times solution, or 50% DT fungicide 350 times solution, or drench the roots. Generally, apply the pesticide once every 10 to 14 d. In the early stage of disease onset, spray with 50% carbendazim wettable powder 500 times solution, or drench the roots with 70% thiophanate-methyl 500 times solution, spraying (drenching) once every 7 to 10 d, for 2 to 3 consecutive sprayings (drenchings).