POST HARVEST FUNGAL DETERIORATION OF SWEET POTATO (Ipomoeabatatas(L)Lam) ELITE VARIETIES INSOUTH EASTERN NIGERIA

Assessments of the pathogenicity of the postharvest spoilage of tubers of elite cultivars of sweet potato (Ipomoea batatas (L)Lam) from different locations in the South eastern Nigeria agroecological zone were carried out between October 2020 – March 2021. Isolated fungi include Botryodiplodia theobromae, Rhizopus stolonifer, Fusarium oxysporum, Penicillium citrinum, Aspergillius niger, and Trichoderma viridie. All the isolates proved pathogenic except T. viride. Of all the isolated fungal pathogens, B. theobromae had the highest percentage occurrence of 36.07% followed by R. stolonifer at 29.02%. Percentage occurrence varied (P<0.05) significantly within the locations surveyed. The more humid location - Umudike (Abia State) indicated higher incidence while the drier location – Ezillo (Ebonyi State) recorded lower fungal growth and disease incidence. The local sweet potato variety (Ex-Igbariam), gave consistently the highest disease severities when inoculated with the three major pathogens –B. theobromae, F. oxysporium, and R. stolonifer. The trend of susceptibility of the cultivars was Ex-Igbariam >UMUSP/2 >UMUSPO/3. The deep orange fleshed cultivar (UMUSPO/3) showed the least mean internal lesion diameter (MILD) of lengths: 10.20mm, 8.60mm, 10.20mm and depths 5.20mm, 5.50mm, 6.20mm on B. thoebromae, F. oxysporium, R. stolonifer respectively. Further research is needed to explore opportunities of scaling up selection of sweet potato lines with vitamin B6 carotenoids ready to provide disease resistance in stored sweet potato in the Southeastern Nigeria.