- Narrow. Southeast Asia, Oceania. On coconut. Usually, a minor disease. More severe in wet areas of the interior of some Pacific islands.
- Threads of the fungus in patches on the underside of leaflets of older fronds, often at the ends, causing rots near the mid-rib.
- Spread is thought to be by spores; also, by contact between leaflets.
- Cultural control: avoid shade, or planting in forests; use wide spacing (normal is 7.5x7.5 m) or intercrops; if planting on slopes, make sure they face the morning sun so that leaves dry rapidly; cut out rots and burn.
- Chemical control: none recommended.