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Cassava mosaic disease
African cassava mosaic virus · Viral
Photo: Albert Cintract (Institut National d'Agronomie Coloniale) · Public domain
Cassava mosaic disease (CMD) is a viral disease of cassava caused by cassava mosaic geminiviruses such as African cassava mosaic virus and East African cassava mosaic virus. It spreads two ways: inside infected stem cuttings used as planting material — the main driver — and by the whitefly (Bemisia tabaci, a tiny white sap-sucking insect), which ferries the virus from plant to plant and into new fields. Plants grown from infected cuttings are diseased from their very first leaf and suffer the heaviest losses. It is the single most important disease of cassava across sub-Saharan Africa.
Raizkgh (Wikimedia Commons) · CC0 
Alphonse Fritz (Institut National d'Agronomie Coloniale) · Public domain
Why it matters
Cassava mosaic disease is the most damaging disease of cassava — a bad infection can take up to 90% of your root harvest, leaving almost nothing to eat or sell. It is a virus, so no spray can cure a plant once it is infected. Worst of all it hides inside the stem cuttings you plant, so you can plant the disease without knowing, and whiteflies (tiny white insects on the leaves) keep carrying it from plant to plant. That is why your only real defence is planting clean, resistant cuttings and pulling out sick plants the moment you see them.
When to act
Rogue symptomatic plants as soon as mosaic appears; treat the field as high risk when whitefly numbers on top leaves are high.
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 cassava mosaic disease field guide
- Identify it
- Scout for it
- Control it
13 field-guide sections in the app
The full guide to cassava mosaic disease — 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 cassava mosaic disease?
The tell-tale sign: young leaves show a patchwork of yellow and green on the SAME leaf — pale yellow or whitish blotches mixed with normal green, like paint that was never stirred. This 'mosaic' or mottling is the classic sign and shows up first on the youngest leaves at the growing tip.
When should I take action against cassava mosaic disease?
Rogue symptomatic plants as soon as mosaic appears; treat the field as high risk when whitefly numbers on top leaves are high.
How do I control cassava mosaic disease?
Best defence — plant a resistant variety: grow an improved CMD-resistant (or tolerant) cassava variety from your national programme or a trusted source. 'Resistant' means the plant can meet the virus and still give a good root harvest. This is the cheapest and most reliable protection of all, and you decide it before you even plant.
Which crops does cassava mosaic disease affect?
Among the crops covered here: Cassava.
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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