Bacterial biocontrol strains that reduce Rhizoctonia damping-off in tomato seedlings

To suppress the Rhizoctonia damping-off in tomato seedlings we used several antagonistic bacterial strains of Bacillus subtilis, B. amyloliquefaciens, B. pumilus and Mycobacterium alvei. These bacterial strains were previously selected for their in vitro ability to control Rhizoctonia solani and were formulated as alginate pellets. The experiment was performed in a growth chamber on tomato cultivar HEINZ 2274. To compare our results with a standardized fungicide we used a chemical treatment with thiophanate-methil, together with other two experimental controls, a negative one, without treatment and a positive one, uninfected. Results showed that the selected strains of B. amyloliquefaciens, B. pumilus and Mycobacterium alvei expressed a biocontrol activity with 37,5 % efficacy in reducing the Rhizoctonia damping-off in tomato seedlings, equivalent to the chemical treatment. However, the 98a strain of Bacillus subtilis expressed 50 % efficacy in Rhizoctonia biocontrol.