Pacific Pests, Pathogens and Weeds

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Summary

• Widespread distribution. Asia, Southeast Asia, Oceania. Ghost spot has probably the widest distribution, and is likely to be present wherever the crop is grown. On taro. Minor diseases.
• Ghost leaf spot (Cladosporium), orange leaf spot (Neojohnstonia), white leaf spot (Pseudocercospora) and shot-hole (Phoma). On older leaves.
• Ghost – reddish-brown with light brown centres, not all penetrating to the undersurface; orange – yellow-brown, sometimes with yellow border; white – whitish-green, dark centres below, leaving white margin; shot-hole – brown up to 20 mm (larger than others), centres fall out leaving hole with yellow halo. All are spread in wind and rain.
• Cultural control: none recommended, as the spots are unlikely to affect yields.
• Chemical control: none recommended.