Bacterial Wilt

Bacterial wilt often causes rapid wilting of whole plants or individual stems, sometimes with little preceding yellowing. A useful field diagnostic is the cut-stem test: a freshly cut, symptomatic stem suspended in a glass of clear water often streams a milky, thread-like bacterial ooze within a few minutes.

The bacteria survive in soil, water, infected plant debris, and some weed hosts for extended periods. They enter plants through root wounds, natural openings, or infected vegetative planting material, then multiply within xylem vessels, physically and physiologically blocking water transport.

• Infected seed tubers, cuttings, or other planting material can introduce the pathogen into a previously clean field
• Contaminated irrigation water and surface water can spread bacteria between plants and fields
• The bacteria can persist in soil and some weed hosts between susceptible crops

Bacterial wilt affects a very wide range of solanaceous and other crops. Tomato, potato, cassava, and ginger are notable hosts, and many other vegetatively propagated crops are also affected in different regions.

• Warm temperatures combined with high soil moisture or waterlogging
• Use of infected seed tubers, cuttings, or other planting material
• Movement of contaminated irrigation or surface water between fields
• Poorly drained soils that retain moisture around roots

Because bacterial wilt spreads through water, soil, and planting material rather than airborne spores, prevention centres on clean planting material, water management, and sanitation.

• Use certified, pathogen-free seed tubers, cuttings, or other planting material
• Improve field drainage and avoid waterlogging where practical
• Avoid moving water, soil, or equipment between infected and clean fields
• Rotate away from susceptible hosts and remove infected plants and debris promptly