Field and storage fungi diseases of yam (Dioscorea spp. L. Wap) in major producing areas in Nigeria

<p>Alexander Adi Bem</p>

Field and storage fungi diseases of yam (Dioscorea spp. L. Wap) in major producing areas in Nigeria

Alexander Adi Bem

Federal University, Nigeria

: J Plant Physiol Pathol

Abstract

Field and storage studies of fungi diseases of yam varieties grown among farmers in some major yam producing areas of Nigeria were carried out from 2014-2017 survey of diseased vines and leaves were determined using disease symptoms. Disease incidence and severity on vine and leaves were determined using disease index and severity score ratings. Diseased vines and stem s together with soil samples were collected for culture, isolation, and identification of pathogens. Deterioration of tuber in the various storage band s was determined by recording the number of rotted and sprouting g tubers. Results showed signs and symptom s such as yellowing of leaves, dark stem s, and necrotic region s on both stem s and leaves were common. Disease incidence on Dioscorea rotundata ranged from 33.58% - 41.75%, Dioscorea alata ranged from 43.33%-45.00% and disease severity of 1 (1-25%) on the disease severity scale rating in both varieties respectively of the area studied. Major pathogen s isolated from the field and storage yam bands included Colletotrichum gloesporides, Neurospora spp., Aspergillus oxysporum, Rhizoctonia solani and Butryodiplodia theobromae. It further showed that occurrence of pathogens on the field are highly in correlation with those in storage. Rot incidence and severity in the different storage bands ranged between 1.67%-27.00% i.e. 1 and 2 on severity scales. Significant differences (P = 0.05) were observed. Infection by rot organisms begin from the field and end up in storage bands leading to tuber deterioration.