Field Survey of Symptoms and Isolation of Fungi Associated with Post-harvest Rots of White Yam (Dioscorea Rotundata Poir.)

Abstract

Investigations were carried out on field survey of symptoms and isolation of fungi associated with the Post-harvest rots of white yam (Dioscorea rotundata Poir.) at Orlu, Imo State. The results of disease incidence and severity showed that dry rot had the highest percentage incidence of 67.5%, followed by wet rot (47.5%) and soft rot 45.0%. Anthracnose recorded 37.5% and powdery mildew recorded 42.5%. The severity result also followed the same trend, with dry rot having the highest percentage of 26.8%, soft rot 23.7%, wet rot 23.2%, anthracnose 16.3% and powdery mildew recorded 15.1%. The fungi were isolated and identified as Trichoderma viride (Pers.), Pythium aphanidermatum (Edson), Aspergillus fumigatus (Fresenius), Penicillium expansum (Link.), Geotrichum candidum (Link.), Fusarium oxysporum (Link.), Botryodiplodia theobromae (Sac.) and Aspergillus niger (van Thieghem). Fungal organisms occurred consistently with soft rot, dry rot, wet rot and anthracnose of D. rotundata with A. fumigatus (Fresenius) occurring more frequently, 45.00%, followed by T. viride (Pers.) 20.00%, P. aphanidermatum (Edson) recorded 15.00%, P. expansum (Link.) and G. candidum (Link.) have 10.00% each.