Controlling soybean root rot pathogens using some safe organic compounds

Laboratory and greenhouse experiments were carried out during the summer season of ۲۰۲۳ to study the effect of some safe organic compounds i.e. humic acid (HA), amino acids (AA) and proline for controlling damping-off and root rot diseases compared to Rizolex-T۵۰® Wp as a fungicide. Rhizoctonia solani, Fusarium solani and Macrophomina phaseolina were isolated from naturally-infected soybean fields and identified as a causal pathogen of damping-off and root rot. R. solani exhibited a highest frequent followed by F. solani while M. phaseolina comprised the least pathogen frequent isolates. In pathogenicity test under greenhouse experiment, R. solani isolate No ۶, F. solani No ۳ and M. phaseolina No ۵ were the most aggressive isolates for causing damping-off and root rot diseases. In laboratory experiment, proline and humic acids displayed fungicidal activity against mycelia growth of root rot fungi. The high level of proline (۳۰۰ ppm) was the most effective followed by humic acid at high level (۳۰۰۰ ppm). In artificially-infested soil with a mixture of pathogenic fungi under greenhouse, Rizolex-T۵۰® Wp exhibited the highest reduction of pre, post-emergence damping-off, root rot and wilt diseases. Morover, from the application trails, the best protection against the causal pathogens of soybean damping-off, root rot and wilt was recorded by prolin at ۳۰۰ ppm followed by HA at ۳۰۰۰ ppm. Herein, it is suggested that soaking of soybean seeds in proline ۳۰۰ ppm or humic acid ۳۰۰۰ ppm before sowing could be considered as alternative safe methods for chemical fungicides to control root rot diseases.

Keywords:

Soybean , Root rot , Organic compounds , humic acid , Amino acids , Proline