Evaluation of Epiphytic Microflora as Antagonists of Red Rot Pathogen, Colletotrichum falcatum in Sugarcane under Subtropical Conditions

Epiphytic microflora isolated from different plant parts of healthy sugarcane plants at different growth stages were assessed for their ability to control fungal red rot pathogen of sugarcane both in vitro and in vivo. Microbial population was higher in the month of August with highest on cane stalk followed by buds and dry leaves. A total of 112 bacterial isolates representing 16 morphotypes, 63 fungal and 35 actinomycete isolates representing 7 morphotypes each and 21 mould isolates of 3 morphotypes were purified from the collection of isolates obtained from different plant parts at different periods of plant growth stage and environment condition. These 231 microbial isolates were screened in vitro for their antifungal activity against Colletotrichum falcatum using dual culture technique. None of the mould isolates could inhibit C. falcatum growth, while 12 bacterial isolates, 4 fungal isolates and 5 actinomycete isolates were found to be antagonistic to C. falcatum. Biochemical and 16SrRNA partial sequence characterization of 12 bacterial isolates led to identification of Pseudomonas, Serratia, Bacillus, Paenibacillus, Gluconacetobacter, Serratia marscens (DQ144501) and Paenibacillus macerans (DQ144502). Based on colony morphology, spore arrangement and structure characteristics the fungal and actinomycete isolates were identified to of Aspergillus, Trichoderma and Penicillium and of Streptomyces and Saccharopolyspora sp., respectively. The strongest inhibition of C. falcatum was obtained with actinomycete isolates and Serratia marscens both under in vitro and in vivo conditions, that can serve to be part of integrated disease management (IDM) of red rot in sugarcane in subtropics.