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.