Effects of Antagonistic Microorganisms on the Postharvest Development of Colletotrichum-Gloeosporioides on Mango

Potential microbial antagonists of Colletotrichum gloeosporiodes were isolated from blossom. leaves and fruit of mango and screened using a series of assay techniques. In total 648 microorganisms, including bacteria, yeasts and filamentous fungi, were isolated and tested for their inhibition of growth of C. gloeosporioides on malt extract agar. In vitro, 121 organisms inhibited the fungus and were tested further for their ability to affect conidial germination. Of these isolates, 45 bacteria and yeasts inhibited germination. These were inoculated onto mangoes artificially infected with C. gloeosporioides and assessed for their potential to reduce the development of anthracnose lesions. Seven isolates were chosen for use in a trial in the Philippines using freshly harvested fruit. This final screening procedure yielded two potential candidates for further trials, isolate 204 (identified as Bacillus cereus) and isolate 558 (identified as Pseudomonas fluorescens). In post-harvest trials under commercial conditions, isolates 204 and 558 were both tested in combination with different application methods including the addition of adhesive material, peptone, fruit wax or sucrose polyester. Application of isolate 204 did not reduce disease development, whereas application of 558 significantly reduced anthracnose development. No additional benefit was achieved by incorporating the bacteria in adhesive material, peptone, fruit wax or sucrose polyester.