Divisi
Bacterial soft rot
Pectobacterium carotovorum · Bacterial
Photo: Scot Nelson · CC0
Bacterial soft rot (Pectobacterium carotovorum) is a soil- and water-borne bacterial disease of fleshy crops — potato, sweet-potato, carrot, onion, cabbage and tomato. The bacteria cannot break through healthy skin; they slip in through wounds, bruises, insect holes and natural openings, then release enzymes that dissolve the tissue and turn firm flesh into a wet, stinking mush. It moves in irrigation water, on dirty knives and crates, on insects and in bruised produce, and is worst in warm, wet, airless conditions — in a waterlogged field or a hot, closed store.
Scot Nelson · CC0 
Scot Nelson · CC0
Why it matters
Soft rot is a silent store-killer. Once it starts, it can rot away up to half your harvest (50%) — and worst of all it keeps working after you have lifted the crop, so a field that looked fine turns into a slimy, stinking heap in the store within days. One rotten potato, onion or cabbage touching its neighbours passes it on, so the loss spreads on its own. There is no spray that cures it: once the flesh has gone to mush it is finished, so everything depends on stopping it before it starts — keeping the crop unbruised, dry and cool.
When to act
First soft mushy lesions on tubers, roots or heads, especially after rain or in store; act on sanitation and drying immediately.
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 bacterial soft rot field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to bacterial soft 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 bacterial soft rot?
The damage you see first: a soft, watery, mushy patch on a potato, sweet-potato, carrot, onion, cabbage head or tomato that gives way when you press it — like a rotten tomato. The flesh collapses into a wet, slimy, cream-to-tan mush and often carries a strong, foul, sickening smell that is easy to recognise once you have met it.
When should I take action against bacterial soft rot?
First soft mushy lesions on tubers, roots or heads, especially after rain or in store; act on sanitation and drying immediately.
How do I control bacterial soft rot?
Prevent it — handle gently and keep dry (the strongest defence): the bacteria need a wound and free water, so give them neither. Harvest in dry weather, avoid bruising and cutting when you lift and carry, let the crop cure and dry before you store it, improve field drainage and never over-irrigate, and store the crop cool, dry and well ventilated — never in a hot, closed, damp heap. Control the insects that chew entry wounds, since every hole is a doorway.
Which crops does bacterial soft rot affect?
Among the crops covered here: Cabbage, Carrot, Onion, Sweet potato, Tomato.
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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