Lethal Yellowing
Candidatus Phytoplasma palmae
A fast, fatal disease of coconut and many other palms, caused by a phytoplasma spread by a sap-feeding planthopper. It kills a mature palm within a few months, dropping its fruit, blackening its flowers, and collapsing the crown.
🔎 How to spot it
On coconut the symptoms appear in order: most or all of the nuts drop prematurely with a brown-black, water-soaked area at the stem end; newly emerging flower spikes blacken and die; then the fronds discolor, yellowing from the oldest, lowest leaves upward (or browning in some dwarf types). Finally the spear (youngest) leaf collapses, signaling the growing point has died, and the whole crown withers and topples.
🥀 Damage it causes
The disease is lethal. Once symptoms begin, infected palms usually die within 3 to 5 months, and outbreaks can kill large numbers of palms across a region. Because the bud itself dies, there is no recovery once the spear leaf has collapsed.
🔬 What causes it
A phytoplasma (Candidatus Phytoplasma palmae), a wall-less bacterium that lives in the palm phloem and cannot be cultured. It is carried palm to palm by a planthopper vector (Haplaxius crudus) as it feeds. Tall-type coconuts such as Jamaica Tall are highly susceptible, while Malayan Dwarf and Maypan hybrids are more resistant, though that resistance has weakened in some areas.
🛡️ Prevent it
The main defense is planting resistant cultivars or non-host palm species where lethal yellowing occurs, and removing diseased palms promptly to cut the source of infection. Managing the planthopper vector and avoiding moving infected material also slow its spread.
🧯 If it is already here
Valuable palms can be protected and early infections held back with trunk injections of the antibiotic oxytetracycline (OTC) on a repeating schedule, but this only suppresses the disease and must be kept up. Palms already showing more than about a quarter of their leaves discolored, or with a collapsed spear, cannot be saved and should be removed.
💡 Good to know
Premature drop of nearly all the nuts together with blackened new flower spikes is the early warning, well before the fronds yellow. Because the bud dies, a collapsed spear leaf means the palm is lost, so replanting with resistant types is the durable answer.
🌱 Plants it affects
2 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.