Divisi
Charcoal rot
Macrophomina phaseolina · Fungal
Photo: Edward L. Barnard, Florida Department of Agriculture and Consumer Services · CC BY 3.0 us
Charcoal rot is a fungal disease of hot, dry, stressed crops caused by a soil fungus (Macrophomina phaseolina) that attacks a very wide range of crops — beans, cowpea, groundnut, soybean, chickpea, sunflower, sesame, sorghum and maize. The fungus lives for years in the soil and in old crop stalks as tiny black specks, quietly infects the roots early on, then strikes when the plant is filling grain in hot, dry weather — plugging the pipes that carry water up the stem so the plant wilts and dries off before its time.
Photchana Trakunsukharati, Department of Agriculture, Thailand · CC BY 3.0 au 
Photchana Trakunsukharati, Department of Agriculture, Thailand · CC BY 3.0 au
Why it matters
Charcoal rot can take up to half your crop (50%) in a bad, dry year — and it hits at the worst time, when your plants are filling grain and you are counting on the harvest. The hard part is there is no spray that cures it: by the time you see plants wilting and drying, the fungus is already inside the stem and those plants are lost. It also lives in the soil for years, so once a field has it, it comes back whenever the weather turns hot and dry. That is why the whole fight is about keeping your crop un-stressed and stopping the disease before it starts.
When to act
A management (not spray) trigger: on susceptible crops in hot, drought-prone fields, act pre-emptively through irrigation and rotation; scattered wilting plants in late season confirm the problem.
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full charcoal rot field guide
- Identify it
- Scout for it
- Control it
15 field-guide sections in the app
The full guide to charcoal rot — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify charcoal rot?
The first thing you see: healthy-looking plants that suddenly wilt and dry off early, still standing, in scattered spots or patches — while the rest of the field is still green. It usually shows during a hot, dry spell when the plants are filling grain or pods. The leaves yellow, then go brown and crispy, and the plant ripens too early, with small, shrivelled, poorly-filled grain or pods.
When should I take action against charcoal rot?
A management (not spray) trigger: on susceptible crops in hot, drought-prone fields, act pre-emptively through irrigation and rotation; scattered wilting plants in late season confirm the problem.
How do I control charcoal rot?
Prevent it — keep the crop un-stressed (your strongest tool). This fungus only wins when the plant is stressed by heat and drought. If you can water, irrigate during hot, dry spells at flowering and grain-fill to keep the crop from drought-stressing — even one or two well-timed waterings in a dry spell can save it. Do not over-crowd: plant at the recommended spacing so plants are not fighting each other for water. Balance your fertiliser and avoid too much nitrogen, which pushes soft, lush growth that then wilts hard when the water runs short.
Which crops does charcoal rot affect?
Among the crops covered here: Chickpea, Common bean, Cowpea, Groundnut, Maize, Sesame, Sorghum, Soybean.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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