Narrow distribution. In Papua New Guinea, Solomon Islands and Taiwan, in dry land and swamps. An important nematode disease.
The nematodes attack roots causing wilts, and invades corms from the base, causing brown, crumbling rots. Healthy parts turn red.
Spread short distances by swimming or being moved in ground water. Long distance movement in planting pieces ('tops').
Cultural control: remove roots from the tops, and inspect corm piece; do not plant down slope from previously infected fields; use hot water (51°C for 10 minutes) to establish source of disease-free plants.