Biological Control of Alternaria solani by Bacillus subtilis NJ-18

Abstract:

Strong inhibition of Bacillus subtilis strain NJ-18 on mycelia growth of Alternaria solani was observed in the antagonistic tests by cylinder plate methods, and the inhibition width was 21.5 mm. Observation under microscope found that the supernatant of fermentation from NJ-18 could make the pathogen hyphae cells malformed and swelled, and consequently the growth of the pathogen was inhibited. Determining of the colonization in potato plants by the signed rifampicin-resistance in NJ-18 showed that it could colonize well in the plants, the colonization quantity of NJ-18 in the root and stem of the potato detected 30 days after fermentation irrigation was 103 CFU/g plant’s fresh weight. In pot experiment, we inoculated the tomato plants with the spore suspensions of Alternaria solani after spraying the fermentation of NJ-18, the results were investigated in 14 days and the efficacy in controlling the disease was 72.9%, which was significantly higher than 45.7%, the efficacy resulted from spray treatment of 2000 fold dilution of 50% iprodione wetable powder.