- Narrow. Africa, South America, Caribbean. NOT recorded from Oceania.
- Major virus disease of cultivated yams causing yellow/green patterns (mosaics), vein-banding, distortions on leaves, stunting, and lower tuber yield. Sometimes, sets slow to sprout, poor vigour and long, thin leaves giving ‘shoe-string’ symptom. Symptoms may disappear with age.
- Spread: aphids by flight and on the wind. Transmission in non-persistent manner - aphids acquire YMV quickly, transmit it over next few hours, then lose ability to infect. Spreads also in sets for propagation.
- Biosecurity: risk from different strains; unofficial introductioins, and trade in tubers. Official movement of germplasm should always follow the FAO/IPBGR Technical Guidelines.
- Biocontrol: none.
- Cultural control: choose only healthy (largest) tubers for sets; rogue plants that show early YMV symptoms to prevent them being used as sets next season. Weed to remove aphid infestations; collect and destroy or eat undersized tubers at harvest. Resistant lines may be available through international breeding programs.
- Chemical control: not appropriate for this disease.
