Abstract

Crude extracts of wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myriocarpus) fruits have been used extensively in animal, human and plant health in marginal communities of South Africa. However, collected fresh fruits of Cucumis species have high rate of post-harvest decay, without information on disease-inducing causal agents. A study was carried out to isolate, identify, perform pathogenicity tests and develop possible tactics to manage the rate of decays. Spores of isolated fungus from harvested fruits were repeatedly cultured on potato dextrose agar. Based on purity and morphological features, the pathogen was isolated, identified and confirmed through pathogenicity tests as Penicillium simplicissimum. The rate of decay was higher in C. africanus than in C. myriocarpus fruits. Overall, proliferation of P. simplicissimum as shown by purity of cultures, suppressed the growth of tactical contaminants, suggesting the existence of antimicrobial-excreting properties in this pathogen. Dipping fruits in 12.5 µg benomyl 50% WP/L tapwater prevented post-harvest decay for over 60 days. In conclusion, association of P. simplicissimum with post-harvest fruit decay in Cucumis species promoted the potential of long-term storage for use of fresh fruit in animal and plant health.

Key words: Cucumis africanus, Cucumis myriocarpus, pathogenicity test, Penicillium simplicissimum,traditional medicine.