Bacterial wilt
Sudden, complete wilting of a still-green plant in warm wet weather — and a cut stem oozing a milky white bacterial stream in water confirms it.
- Pathogen
- Soil bacterium (Ralstonia)
- Spreads by
- Soil, water, tools & debris
- Favoured by
- Warm, wet, humid conditions
- Main risk
- Sudden collapse; long soil survival
Overview
Bacterial wilt (Ralstonia solanacearum) is a devastating soil-borne bacterial disease of tomato, brinjal, chilli, potato, ginger and many other crops, especially in warm, wet, humid regions. The bacteria enter through the roots, multiply massively in the water-conducting vessels, and block them, so the plant wilts.
What makes bacterial wilt distinctive is the suddenness: a plant can wilt completely while its leaves are still green — no gradual yellowing first — and collapse within a day or two, often the whole plant at once. The classic on-the-spot test is the "ooze test": cut the wilted stem near the base, suspend the cut end in a glass of clear water, and within minutes a milky white thread of bacteria streams out of the cut. The bacterium survives in soil, water and infected debris for a long time, so like Fusarium wilt it is managed with resistant varieties, clean material, soil health and rotation rather than sprays.
How to identify it
- Sudden, complete wilting of a plant while its leaves are still green — often the whole plant collapsing within a day or two, with no gradual yellowing first.
- The ooze test: cut the wilted stem near the base and hang the cut end in a glass of clear water — a milky white stream of bacteria flows out within minutes (this confirms bacterial, not fungal, wilt).
- A cut stem showing browned vascular tissue and, when squeezed, a sticky, milky ooze.
- Wilting worst in warm, wet weather, spreading in patches and along water flow in the field.
What causes it and when
- The soil bacterium Ralstonia solanacearum, which enters through the roots (often via wounds) and blocks the stem’s water vessels.
- Favoured by warm, wet, humid conditions and waterlogged, poorly-drained soil; it flares in the monsoon.
- Spread by infected soil and irrigation/run-off water, on tools and footwear, in infected seedlings and (in potato/ginger) in infected tubers/rhizomes.
- Survives in soil, water and infected debris and volunteer plants for a long time.
Cultural & organic control
- Grow resistant/tolerant varieties and use certified disease-free seed, seedlings and (for potato/ginger) planting material.
- Improve drainage and avoid waterlogging; do not let run-off carry the bacterium from an infected patch across the field.
- Rogue out and destroy wilted plants promptly (with surrounding soil), follow long rotation with non-host crops, and raise soil pH/health as recommended.
- Disinfect tools and avoid working in the crop when wet; on ginger, treat seed rhizomes and use a hot-spot approach.
Chemical control
- There is no spray or antibiotic that reliably cures bacterial wilt in the field — it is managed, not cured.
- A recommended seed/seedling/rhizome treatment and soil amendments (e.g. bleaching powder/lime or bio-agents like Pseudomonas fluorescens) per official recommendation help reduce it in infested soil.
- Focus on prevention and sanitation; do not rely on chemical sprays against this bacterium.
- Confirm the resistant varieties and the recommended treatment for your crop and area with your local KVK.
Prevent it coming back
- Base management on resistant varieties, certified clean planting material, drainage, sanitation and long rotation with non-hosts.
- Never move infested soil, water or plant material to clean fields, and destroy wilted plants and volunteers.
- Once soil is infested it stays a long-term problem, so plan resistant varieties, grafting (where used) and rotation for the long term.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My tomato/brinjal wilted suddenly while still green. Is it bacterial wilt?
Very likely. Sudden, complete wilting of a still-green plant — collapsing within a day or two with no gradual yellowing first — is the hallmark of bacterial wilt. Confirm with the ooze test: cut the wilted stem near the base and hang the cut end in clear water; a milky white stream of bacteria flowing out within minutes confirms it. It is managed with resistant varieties, clean material and drainage, not sprays.
What is the "ooze test" and how do I do it?
It is a simple field test for bacterial wilt. Cut the base of a freshly-wilted stem, and suspend the cut end in a glass of clear water without stirring. If bacteria are present, within a few minutes you will see a milky white thread or cloud streaming down from the cut into the water. That confirms bacterial wilt (fungal wilts do not ooze like this) — so you manage it as a soil bacterium, not with a fungicide.
How do I manage bacterial wilt in an infested field?
Since there is no cure, rely on prevention and management: grow resistant/tolerant varieties, use certified disease-free seedlings and planting material, improve drainage and avoid waterlogging, rogue out and destroy wilted plants with surrounding soil, disinfect tools, and rotate with non-host crops for several seasons. Recommended soil amendments and bio-agents help. Confirm the specifics with your KVK.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.