Bacterial wilt is a serious plant disease caused by the soil-borne bacterium Ralstonia solanacearum (formerly Pseudomonas solanacearum). It affects many plant species, including vegetables, fruits, ornamental plants, and important crops. The disease is characterized by wilting, stunting, yellowing of foliage, and eventual collapse of the entire plant.
Once infected, plants typically die within a few weeks or months. Bacterial wilt can cause significant yield losses and can be particularly devastating in areas with warm, humid climates and heavy rainfall.
Bacterial Wilt Management in Eggplant (Brinjal)
The Disease cycle of Bacterial Wilt
- Bacteria enter xylem vessels: The bacteria enter the xylem vessels of the leaf veins and move down the petiole and vine.
- Bacteria spread to adjacent vessels: The bacteria spread to adjacent vessels through the dissolved cell wall, clogging the plant vessels and causing discoloration of the xylem vessels.
- Bacteria multiply: The bacteria continue multiplying, forming visible ooze masses.
- Beetles lay eggs: Beetles lay eggs near young plants, and larvae attack plant roots. Larvae pupate in the soil and emerge as adults, usually in August.
- Bacteria contaminate beetles: Emerging adults become contaminated with bacteria upon feeding on infected plants.
- Beetles spread bacteria: Beetles feed on and contaminate cucurbit plants with bacteria. Bacteria are deposited with the insect feces on leaf wounds.
- Bacteria overwinter: Bacteria overwinter in the striped and spotted cucumber beetles. Beetles usually appear when plants emerge in spring.
The causal organism of Bacterial Wilt Disease
- Bacterial wilt is primarily caused by the Ralstonia solanacearum bacterium, which can survive in the soil for several years.
- The bacterium mainly inhabits the roots of susceptible plants and enters the root system through wounds caused by farm tools, equipment, or soil pests.
Causes/Conditions favorable for Bacterial Wilt Disease spread in the field.
- High temperatures: Bacterial wilt symptoms are favored by high temperatures ranging between 30-35°C. High temperatures can increase the rate of bacterial multiplication and symptom expression, leading to a rapid spread of the disease in the field.
- High soil moisture: High soil moisture levels can create favorable conditions for the survival and multiplication of the bacterial wilt pathogen. The pathogen can easily spread through waterlogged soils, infecting healthy plants and increasing disease incidence.
Symptoms of Bacterial wilt in Eggplant
- Wilting: The affected plants exhibit wilting symptoms, starting from the lower leaves, which hang and then wilt. The wilting progresses upwards, eventually resulting in the collapse of the entire plant.
- Stunting: Bacterial wilt can cause stunted growth in eggplants, leading to reduced yields.
- Yellowing of foliage: The leaves of affected plants turn yellow, and the foliage may appear wilted and scorched.
- Vascular browning: The vascular system of the affected plant turns brown due to bacterial infection. This symptom is one of the most reliable ways to diagnose bacterial wilt.
- Bacterial ooze: A bacterial ooze may be visible on the affected parts of the plant, such as stems and leaves.
- Noontime wilt: Infected plants may show wilting symptoms during the day, especially at noontime, but recover at night. However, these plants will eventually die.
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