Divisi
Corm rot
Erwinia carotovora · Bacterial
Photo: Scot Nelson · CC0
Corm rot is a soft, wet rot of the corm — the fat underground stem that a banana, taro or cocoyam grows from. It is caused mainly by bacteria (and sometimes fungi) that sneak in through cuts and bruises on suckers and roots. Warm, waterlogged, poorly drained soil and the planting of infected or damaged suckers set it off. The rot eats out the corm tissue, so the plant cannot root or hold itself up: it yellows, wilts and topples.
Scot Nelson · CC0 
Scot Nelson · CC0
Why it matters
Corm rot attacks the one part the whole plant stands on — the underground stem. A bad outbreak can wipe out up to 60% of your crop, because a plant with a rotten corm cannot root, cannot feed itself, and simply topples over and dies. Worst of all, the rot works underground where you cannot see it and spreads through wet soil and dirty planting material, so by the time a plant wilts on top the corm below is often already destroyed and cannot be saved. That is why everything here is about keeping it OUT — clean suckers and dry, well-drained ground — not curing it after.
When to act
Newly planted suckers failing to establish or young plants toppling with a soft rotten base.
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 corm rot field guide
- Identify it
- Scout for it
- Control it
13 field-guide sections in the app
The full guide to corm 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 corm rot?
The first thing you see (above ground): a young plant that yellows, wilts and leans or topples over even though there is no drought — give it a gentle push and it rocks loosely in the soil because the rotten corm no longer anchors it. Newly planted suckers may simply fail to sprout and sit there dying.
When should I take action against corm rot?
Newly planted suckers failing to establish or young plants toppling with a soft rotten base.
How do I control corm rot?
Prevent it — plant clean material (your strongest tool): start only with clean, healthy suckers or, best of all, tissue-cultured plantlets (lab-raised, disease-free baby plants). Pare each sucker — trim off the outer skin and roots — and cut away any brown or smelly spot. Never replant a sucker from a plant that rotted, and avoid bruising or wounding corms when you dig, carry or plant them, because every cut is a door for the bacteria.
Which crops does corm rot affect?
Among the crops covered here: Cocoyam / Taro, Enset.
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.
Check what grows on your farm