Bacterial Wilt

  • Symptoms

  • Trigger

  • Biological Control

  • Chemical Control

  • Preventive Measures

Bacterial Wilt

Ralstonia solanacearum

Bacteria


In a Nutshell

  • First, wilting of the youngest leaves, then of the whole plant.
  • Leaves stay green and attached to stem.
  • Roots and lower parts of the stem become brownish.
  • Roots may rot and exudate yellowish secretion when cut.

Hosts

Capsicum & Chili

Potato

Tomato

Symptoms

The youngest leaves start to wilt during the hottest part of the day and partly recover when temperatures are cooler. Under favorable conditions, the wilting may affect the whole plant and stay permanent. The wilted leaves maintain their green color and remain attached to the stem. The roots and lower part of the stem show a dark brown discoloration. The invaded roots may rot due to infection from secondary bacteria. When cut, stems can exude a white to yellowish, milky secretion.

Trigger

The bacterium can live long in soils, it can survive in plant debris or on alternative hosts. It enters the plant through wounds in the root system during the emergence of lateral roots. Elevated temperatures (from 30°C to 35°C), high humidity and soil moisture, and alkaline soil pH favor disease development. Heavy soils that can retain soil moisture for long periods are particularly vulnerable. Main alternative hosts for Ralstonia solanacearum include tomato, tobacco, plantain and banana.

Biological Control

The incorporation of fresh plant mass (green manure) from the cruciferous family into the soil (biofumigation) can help to control the pathogen. The plant material can be macerated or chopped off before being dug into the soil, either mechanically or by hand. The plant-derived chemical Thymol has the same effect. Competitive bacteria that colonize the root systems of solanaceous plants are also effective.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Because of the soil-borne nature of the causing pathogen, the chemical treatment of the disease may be inviable, less effective or ineffective.

Preventive Measures

Plant resilient varieties.,Ensure pathogen-free soil, irrigation water, seeds, and transplants.,Use suggested planting space.,Provide good drainage to the field.,Crop rotation for periods of 5 years or more.,Ensure a slightly acidic soil-pH of 6,0-6,5.,Ensure a good nutrient supply.,Remove infected plants to avoid spreading.,Avoid transferring equipment from contaminated to uncontaminated soils.,Disinfect tools with bleach before working on the next field.,Destroy all infected plants as well as residues by burning.