Biological control of postharvest mango fruit rot caused by Colletotrichum gloeosporioides and Diplodia natalensis with Candida tropicalis and Alcaligenes feacalis

Postharvest diseases of mango include anthracnose caused by Colletotrichum gloeosporioides, stem-end rot by Lasiodiploidia theobromae, Diplodia stem-end rot by Diplodia natalensis, black mould rot by Aspergillus niger, brown spot by Pestalotiopsis mangiferae and black spot rot by Phomopsis mangiferae. The main constraint in the storage of fruits is loss due to fungal infections. Though there are chemical methods to reduce fungal infections and storage diseases, biocontrol methods provide the option to get chemical free food for consumption. Microflora from mango fruit surface were isolated and screened against C. gloeosporioides and D. natalensis in vitro. Among seventy isolates, five were selected for testing their bioefficacy by fruit dipping method. Fruits of three mango varieties, viz., Totapuri, Dasheri and Raspuri were tested. Cell suspension of selected antagonist isolates at the rate of 2 x 106 CFUs ml-1 was used separately to treat the fruits by dipping method for three min. One yeast isolate (I2) and one bacterial isolate (I4) were found to delay as well as reduce the fruit rot spread caused by anthracnose or stem-end rot pathogens for up to 12 days after treatment in these three varieties. These isolates were identified using molecular methods. Treatment with isolate I2 and I4 resulted in disease severity of 1.2 to 1.3 while in control it was 4.8 and in treatment with I5 it was 3.5 on the twelfth day after treatment. The yeast isolate was identified as Candida tropicalis while the antagonistic bacterial isolate was identified as Alcaligenes feacalis. The potential use of these isolates in postharvest disease management in mango is discussed.