Divisi
Lethal yellowing
· Bacterial
Photo: USDA Forest Service · CC BY 3.0
Lethal yellowing is a fatal disease of coconut palms caused by a phytoplasma — a tiny bacteria-like germ, with no proper cell wall, that lives inside the palm's sap-pipes (the tubes that carry its food). You cannot see the germ. It is carried from palm to palm by a small sap-sucking insect called a planthopper (the vector — the insect that spreads the germ). Once a palm is infected there is no cure: it drops its nuts, its new flowers die, its leaves yellow from the bottom up, and within a few months the whole crown falls and the palm dies. Left unchecked it can wipe out an entire grove.
USDA Forest Service · CC BY 3.0 
USDA Forest Service · Public domain
Why it matters
Lethal yellowing can kill every coconut palm it reaches — that is a 100% loss, not a bad harvest but the death of the tree you waited years to bring into bearing, and often its neighbours too. It matters because a palm takes 5–7 years to grow back, so a lost palm is lost income for many seasons. It is hard to fix because by the time you see the yellowing the germ is already deep in the palm's sap and the planthopper has almost certainly carried it to nearby palms — there is no spray or medicine that saves an infected palm, so your only weapons are catching it early, cutting it out, and planting resistant types.
When to act
any palm showing premature nutfall or fronds yellowing from the bottom up should be flagged and reported immediately, as spread is by leafhopper vectors
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 lethal yellowing field guide
- Identify it
- Scout for it
- Control it
16 field-guide sections in the app
The full guide to lethal yellowing — 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 lethal yellowing?
The first and clearest sign is nutfall: the palm suddenly drops most or all of its nuts at once, and they fall at every size — tiny green buttons, half-grown, and near-ripe all on the ground together. Look at a fallen nut's stem end: you often see a brown, water-soaked rot ring where it broke off. A healthy palm never sheds all ages of nut at the same time.
When should I take action against lethal yellowing?
any palm showing premature nutfall or fronds yellowing from the bottom up should be flagged and reported immediately, as spread is by leafhopper vectors
How do I control lethal yellowing?
PREVENT — plant resistant palms (your strongest tool). When you establish or replant, choose resistant or tolerant coconut types — selected dwarf varieties and hybrids are far less likely to die of this disease than the tall local coconuts. Always get your seednuts and seedlings from a disease-free area, never from a grove where palms have been dying, so you don't carry the germ home in the planting material.
Which crops does lethal yellowing affect?
Among the crops covered here: Coconut.
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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