Fusarium wilt
A soil fungus that blocks the stem’s water vessels so the plant wilts and dies even in moist soil — the browned inner stem is the giveaway.
- Pathogen
- Soil fungus (Fusarium)
- Spreads by
- Soil, seed & infected debris
- Favoured by
- Warm soil; infested fields
- Main risk
- Wilting death; long soil survival
Overview
Fusarium wilt is a soil-borne fungal disease (Fusarium oxysporum) that infects through the roots and grows up into the plant’s vascular system — the vessels that carry water up the stem. By plugging these vessels, it starves the plant of water, so it wilts, yellows and dies even though the soil is moist.
Classic signs are wilting and yellowing that often start on one side of the plant or one branch, drooping in the heat of the day, and — the clinching test — a brown or dark discolouration of the vessels when you split the stem or a branch lengthwise. Different host-specific strains ("formae speciales") attack pigeonpea, chickpea, cotton, pea, tomato, banana (Panama wilt) and many other crops. The fungus survives in soil and on debris for years, so once a field is infested it stays a problem — which is why resistant varieties, soil health and rotation, not sprays, are the mainstay.
How to identify it
- Wilting and yellowing of the plant despite moist soil, often drooping worst in the heat of the day.
- Symptoms frequently starting on one side of the plant or one branch, then spreading — a half-wilted look.
- The clinching test: split the stem or a branch lengthwise and look for brown or dark-stained streaks in the woody tissue (the blocked vessels).
- Scattered dead and dying plants in the field, often in patches, that persist and spread over seasons.
What causes it and when
- The soil fungus Fusarium oxysporum, which enters through the roots and blocks the water-conducting vessels in the stem.
- Host-specific strains attack specific crops (pigeonpea, chickpea, cotton, pea, tomato, banana), so a wilt strain from one crop may not attack another.
- Favoured by warm soil and by infested fields; it survives in the soil and on crop debris for many years.
- Spread by infected soil (on tools, water, animals), infected seed/planting material and root-to-root contact.
Cultural & organic control
- Grow wilt-resistant/tolerant varieties — the single most effective and economical control for Fusarium wilt.
- Use clean, disease-free seed and treat seed/soil with a bio-agent such as Trichoderma viride, which suppresses the fungus.
- Follow long crop rotation with non-host crops to starve the fungus, and improve soil health with organic matter (FYM/compost).
- Rogue out and destroy wilted plants, avoid moving infested soil, and ensure good drainage.
Chemical control
- There is no spray that cures a wilted plant — Fusarium wilt is managed, not sprayed away, because the fungus is inside the plant and the soil.
- A recommended seed treatment (a registered fungicide and/or Trichoderma) at sowing protects the establishing crop and is the main chemical-side measure.
- Soil solarisation and soil amendment with bio-agents help reduce the fungus in badly-infested fields, per recommendation.
- Confirm the resistant varieties and the recommended seed treatment for your crop and area with your local KVK.
Prevent it coming back
- Base management on resistant varieties, clean seed, Trichoderma seed/soil treatment and long rotation with non-hosts.
- Build soil organic matter and drainage, and avoid carrying infested soil and debris between fields.
- Once a field is infested it stays so for years — plan resistant varieties and rotation for the long term rather than expecting a quick fix.
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 plants wilt and die even though the soil is moist. What is it?
Wilting and dying despite moist soil is the hallmark of a wilt disease, most often Fusarium wilt. The soil fungus blocks the water-carrying vessels in the stem, so the plant cannot draw water up even from wet soil. Split the stem lengthwise — brown or dark-stained streaks inside confirm it. It is managed with resistant varieties, clean seed, Trichoderma and rotation, not sprays.
Why does only one side or one branch wilt first?
Because the fungus grows up the water-conducting vessels, and it often colonises the vessels on one side of the stem or in one branch first, so that part loses its water supply and wilts before the rest. This one-sided or single-branch wilting, together with brown-stained vessels inside the stem, is characteristic of Fusarium wilt.
Can I cure Fusarium wilt with a fungicide spray?
No — there is no spray that cures a wilted plant, because the fungus lives inside the plant’s vessels and in the soil. Fusarium wilt is managed, not cured: grow resistant varieties, use clean seed with a Trichoderma/registered seed treatment, rotate with non-host crops, build soil health, and rogue out wilted plants. Once a field is infested it stays a long-term problem.
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.