Dry root rot (charcoal rot)
Sudden wilting and drying in hot, dry, stressed weather, with shredded roots and a stem base peppered with tiny black specks.
- Pathogen
- Fungus (Macrophomina phaseolina)
- Spreads by
- Soil- & seed-borne microsclerotia; debris
- Favoured by
- Hot, dry weather + moisture stress
- Main risk
- Sudden wilting and drying, plants killed
Overview
Dry root rot, also called charcoal rot, is caused by the soil- and seed-borne fungus Macrophomina phaseolina, which attacks a very wide range of crops — chickpea and other pulses, groundnut, cotton, soybean, sorghum, sesame and more. Its signature is sudden collapse: an apparently healthy plant wilts and dries up quickly, often in patches, especially when the crop is under heat and moisture stress at the flowering-to-podding stage.
When such a plant is pulled up, the taproot and lower stem are dry, brittle and shredded, the bark peels easily, and the wood underneath is studded with countless tiny black specks — the fungus’s microsclerotia (giving the "charcoal" look). These microsclerotia survive for years in soil and on debris. The disease is driven by high soil temperature and dry, stressed conditions, so it is far worse in a moisture-stressed, late-sown or terminal-drought crop. Management combines avoiding stress (timely, adequate irrigation), resistant/tolerant varieties, seed treatment and rotation.
How to identify it
- Sudden wilting and drying of apparently healthy plants, often in patches, especially at flowering to podding in hot, dry weather.
- Dry, brittle, shredded taproot and lower stem with bark that peels off easily.
- Countless tiny black specks (microsclerotia) in the shredded root/stem tissue — the "charcoal" sign.
- Worst where the crop is moisture-stressed, late-sown or hitting terminal drought and high soil temperature.
What causes it and when
- The soil- and seed-borne fungus Macrophomina phaseolina, whose microsclerotia survive for years in soil and on crop debris.
- Strongly favoured by high soil temperature and dry, moisture-stressed conditions — a stress disease more than a wet-weather one.
- Usually strikes from flowering onward, when the plant is under reproductive and moisture stress.
- Worse with late sowing, terminal drought, and continuous cropping of susceptible hosts.
Cultural & organic control
- Avoid moisture stress — sow on time and give a timely, adequate irrigation at the critical flowering/podding stage where possible.
- Grow resistant/tolerant varieties and use clean, healthy seed.
- Rotate away from susceptible hosts and incorporate organic matter to build antagonists.
- Treat seed and soil with a bio-agent (e.g. Trichoderma) where recommended.
Chemical control
- Treat seed before sowing with a recommended fungicide (e.g. carbendazim or a carboxin+thiram type dressing) to protect the young plant.
- A soil/root drench with a recommended fungicide can be used around affected patches, but avoiding stress matters more.
- There is no rescue spray for a plant already dried by charcoal rot — control is preventive.
- Confirm the current seed-treatment and any drench for your crop with your local KVK.
Prevent it coming back
- Base the crop on timely sowing, resistant varieties, treated seed and avoiding terminal moisture stress.
- Rotate with non-hosts and build soil organic matter and bio-agents to suppress the microsclerotia.
- Manage irrigation so the crop is not stressed at flowering/podding, when the fungus strikes hardest.
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 chickpea/groundnut plants suddenly dried up in the heat. What is it?
Sudden wilting and drying in hot, dry weather, with a shredded, brittle root and stem base peppered with tiny black specks, is dry root rot (charcoal rot), caused by Macrophomina. It is a stress disease — it strikes hardest when the crop is moisture-stressed at flowering/podding. You cannot revive a dried plant; prevent it with timely sowing, a critical-stage irrigation, resistant varieties and treated seed.
How is charcoal rot different from a wilt disease?
Both make plants wilt, but charcoal rot is driven by heat and drought stress rather than wet soil, and its signature is a dry, shredded root and stem base studded with tiny black microsclerotia (the "charcoal" look), rather than the browned internal vascular tissue of Fusarium wilt. Because it is a stress disease, avoiding moisture stress — a timely irrigation at flowering/podding — is one of the most effective controls.
Does irrigation really help against dry root rot?
Yes — because charcoal rot is driven by high soil temperature and moisture stress, a crop that hits drought at flowering/podding suffers far more. Sowing on time and giving a timely, adequate irrigation at that critical stage keeps the plant unstressed and much less prone to sudden collapse. Combine that with resistant varieties, treated seed and rotation for dependable control.
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.