Occurrence and pathogenicity of fungal genera on Jatropha curcas L. in Southwestern Nigeria.

Summary: Information on the occurrence and pathogenicity of the fungal mycoflora on Jatropha curcas in Nigeria is scarce, and the present study focused on this issue in Southwestern Nigeria. A survey and randomized fungal sample collection were conducted in six Southwestern states (Ekiti, Lagos, Ogun, Ondo, Osun and Oyo) of Nigeria within different Jatropha curcas fields. Observed disease symptoms were recorded and diseased samples were collected for fungal isolation and identification. Pathogenicity tests of the isolated organisms were carried out on 4-week-old J. curcas seedlings using a foliar spray inoculation technique. Data on percentage occurrence of fungal isolates per state were collected and analysed using analysis of variance and mean separation techniques in SAS. Eleven fungal genera were observed to be associated with Jatropha curcas in Southwestern Nigeria. The occurrence of these organisms differed significantly (p ≤ 0.05) per state. Five genera (Curvularia, Colletotrichum, Fusarium, Lasiodiplodia, and Oidium) were confirmed as pathogenic on J. curcas. There were significant differences in fungal occurrence across the states for all the fungal genera except for Colletotrichum spp. It was evident that among the six states, Ekiti, Ondo and Oyo had the highest recorded occurrences of all the fungi isolated from J. curcas with the exception of Corynespora, suggesting that the crop is more susceptible to fungal infections in those three states. [ABSTRACT FROM AUTHOR]