Controlling the Fungal Rot Pathogens of Chrysophyllum albidum (African Star Apple Fruit) Using Ricinus communis (Castor Seed), Elaeis guinnesis (Palm Kernel) and Glycine max (Soybeans) Oil

Abstract

Introduction: C. albidum is a tree plant that bears fruits containing five seeds, the fruits serve as a source of food in Africa, however, pre harvest fungal pathogenic infections reduce the shelf life of these fruits.  Objective: This study was carried out to control the fungal rot pathogens of African star apple fruit (ASAF) (Chrysophyllum albidum) by evaluating the antifungal effects of essential oil from seeds of some tropical plants against the rot pathogens. Materials and Methods: ASAF samples were gotten from main market in Ado-Ekiti, while the seeds of the test plants were locally sourced from vegetation in Ado Ekiti. The fungal pathogens isolated from rotten African star fruits were subjected to pathogenicity test. The isolated fungi from ASAF were: Aspergillus flavus, Aspergillus niger, Pennicillum sp, Rhizopus stolonifer and Aspergillus fumigatus.   Results: Aspergillus flavus (45%) and Aspergillus fumigatus (5%) had the highest and lowest percentage occurrence respectively. Oils from castor seed, palm kernel and soybean were extracted using Soxhlet extractor. The fungal inoculum was prepared from 5-day old culture grown on potato dextrose agar medium and the effects of the oils were determined. The sensitivity of the fungal isolates to oils were found by assessing the diameter of the mycelial growth inhibition in which significant susceptibility was taken as ≥ 7 mm in diameter, The effects of the plant oils showed that the oils were more effective at higher concentrations and all the oils had significant inhibitory effects on the fungal pathogens. Castor oil was most effective among all the assayed oils, it inhibited the fungal mycelial growth of Aspergillus niger (24.00mm) at 103 concentrations, Aspergillus flavus (30.00mm) at 103 concentrations, Penicillum species (28.00mm) at 103 concentrations, Rhizopus stolonifer (25.00mm) at 103 concentrations, Aspergillus fumigatus (30.00mm) at 103 concentrations. The nutrient composition of infected showed a reduction in the nutrient composition compared with the fresh and healthy fruit. Conclusion: The use of biological control of plant disease using plant oils has been found effective against fungal pathogens of C. albidum.