Yams (Dioscorea rotundata Poir and D. alata Lam.) fungi etiology in Katsina-Ala Local Government Area of Benue State, Nigeria

A study was carried out on the incidence, isolation and identification of fungal pathogens of the leaves of cultivated white yam, Dioscorea rotundata Poir and water yam, Dioscorea alata Lam found on four farmers’ fields between August and October 2010. Farm locations used included those in Tse-Ugba, Tor-Donga, Abaji-Kpav and Katsina-Ala in Katsina-Ala Local Government Area of Benue State of Nigeria. Diseased leaves and vine samples were randomly collected from some fields during the study. Isolations were made from the leaves and vines samples. The fungal pathogens were grown on Potato Dextrose Agar (PDA) after inoculation using diseased leaves and stems after surface sterilization. Pure cultures of fungal pathogens were recovered on PDA using mycelia from initial culture. The study revealed that the mean percentage disease incidence on D. rotundata ranged from 33.58% to 41.75%. Mean disease severity on D. rotundata was found to be between 10.05% and 10.58%. The result also showed that mean percentage disease incidence on D. alata was between 43.33% and 47.08%. Mean disease severity was observed to be between 9.18% and 9.78% indicating that only mild disease severity on the plants in this area was observed. The fungus isolated from the disease yam leaves in each of the sites was identified as Colletotrichum gloeosporioides suggesting that only this organism was the primary leaf-disease fungus in the study area.