Morphological and molecular identification of pathogenic fungi of Monodora myristica Dunal kernels and their response to different phytoextracts

Identification of fungi from calabash nutmeg kernels was based on their morphological characteristics and analysis of the internal transcribed spacer (ITS) sequences of their genomic DNA. Antifungal activity of aqueous, methanolic and ethanolic extracts of four plants species (Azadirachta indica, Citrus sinensis, Moringa oleifera and Tithonia diversifolia) was tested in vitro at 50, 75, 100 and 125 mg/ml for aqueous extracts and 40, 60, 80 and 100 mg/ml for methanolic and ethanolic extracts. Mancozeb (1 mg/ml) and distilled water were used as positive and negative controls, respectively. The most frequently isolated fungi were Cercospora purpurea (34.28%), Fusarium oxysporum (23.81%) and Aspergillus flavus (17.14%). C. purpurea and F. oxysporum isolates were more aggressive after inoculation on healthy kernels. All the extracts tested, inhibited the growth of the fungi compared to the negative control, except the aqueous extract of T. diversifolia against C. purpurea and F. oxysporum and the methanolic extract of M. oleifera against F. oxysporum at 75 mg/ml. The efficiency of aqueous extracts of M. oleifera and C. sinensis was significantly lower (P<0.05) as compared to the reference fungicide on growth of A. niger at 125 mg/ml. Antifungal activity of methanolic extracts of A. indica, C. sinensis and T. diversifolia as well as ethanolic extracts of A. indica and M. oleifera was significantly equal to mancozeb at 100 mg/ml on A. flavus. Aqueous extracts of M. oleifera and methanolic extracts of A. indica and C. sinensis could be used for protection of Monodora myristica kernels against post-harvest fungi.