Efficacy of crude extract of antifungal compounds produced from Bacillus subtilis on prevention of anthracnose disease in Dendrobium orchid

The aim of this study was to evaluate the antifungal efficacy of crude extracts of antifungal compounds produced from Bacillus subtilis SSE4 against plant fungal pathogen; Colletotrichum gloeosporioides. Antifungal compounds in culture filtrate were extracted by ethyl acetate, hexane or dichloromethane and assessed for their efficacy to inhibit the growth of C. gloeosporioides on agar plates and for prevention of anthracnose disease in Dendrobium. The results showed that crude extracts of antifungal compounds extracted by all solvents were able to inhibit the growth of C. gloeosporioides. However, antifungal compounds extracted by ethyl acetate and hexane showed higher percentages of fungal growth inhibition than that of antifungal compounds extracted by dichloromethane. In addition, the application of crude extract of antifungal compounds extracted by ethyl acetate showed higher efficacy on prevention of anthracnose development in orchid leaves than that of crude hexane extract of antifungal compounds. The efficacy of crude ethyl acetate extracts of antifungal compounds on anthracnose prevention was similar to that of chemical fungicide application. These results indicated that antifungal compounds extracted by ethyl acetate as biofungicide could replace chemical fungicides for orchid cultivation.