Divisi
Cassava mealybug
Phenacoccus manihoti · Insect
Photo: MJN2000 · CC0
Cassava mealybug (Phenacoccus manihoti) is a soft-bodied, sap-sucking insect, hidden under white powdery wax, that colonises the growing tips of cassava. As it feeds it injects a toxic saliva that shortens the stem joints, bunching the top leaves into a tight 'cabbage-head' rosette and stunting the whole plant. It multiplies explosively in the hot, dry season and spreads mainly on infested stem cuttings. It is the textbook success story of biological control in Africa: the introduced parasitoid wasp Anagyrus lopezi now holds it in check across the cassava belt wherever farmers avoid killing it with broad sprays.
Why it matters
Cassava mealybug can strip away up to 60% — well over half — of your cassava, shrinking both the roots you eat and the stems you keep for next season's cuttings. It attacks the soft growing tip, bunches the top into a useless 'cabbage head', and multiplies fast through the hot, dry months. It is hard to beat once it is in, because a waxy coat shields it from sprays and it travels hidden on the very cuttings you plant — so an infested field replants the problem year after year. The good news: your strongest ally is free — a tiny helper wasp already lives in Africa's cassava fields and will hold the pest down, as long as you do not kill it with broad poisons.
When to act
Colonies of pink-white mealybugs on shoot tips causing bunching of top leaves; scout during the dry season.
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 mealybug field guide
- Identify it
- Scout for it
- Control it
14 field-guide sections in the app
The full guide to cassava mealybug — 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 mealybug?
The damage you see first: the top of the plant stops stretching and the young leaves bunch into a tight, crumpled 'cabbage head' or shaving-brush tip — the joints between the leaves shrink so the leaves stack up in a little rosette. Below it, leaves yellow, curl and drop, the shoots die back, and the whole plant looks stunted.
When should I take action against cassava mealybug?
Colonies of pink-white mealybugs on shoot tips causing bunching of top leaves; scout during the dry season.
How do I control cassava mealybug?
Prevent it — plant clean cuttings (your most important step): the insect travels from field to field hidden on cassava stems. Take cuttings only from healthy plants with no white wax and no bunched tips, and throw away any stick that has mealybugs on it. Never carry, sell or share cuttings from an infested field — you would simply be planting the problem somewhere new.
Which crops does cassava mealybug 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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