The possibilities on biological control of tomato bacterial speck disease with bacterial antagonists

Bacterial Speck Disease caused by Pseudomonas syringae pv. tomato is an important bacterial disease that causes yield losses on tomatoes. In the study a total of 323 candidate bacterial antagonist strains were isolated from tomato soils and roots in Erdemli and Toroslar districts of Mersin. Antimicrobial effects of the strains were investigated by In vitro petri dishes and 12 strains suppressed the growth of the pathogen with the inhibition zones between 2.3 and 11.0 mm. The stains reduced the disease incidence by 33-95% and disease severity by 28-95% when the twelve strains were applied to tomato seeds as biological seed treatments. In the second seed experiment with the most successful strains, the disease was suppressed by 81-100% ratios. The antagonistic strains didn't pose a negative effect on seed germination. The antagonistic bacterial strains were identified as Bacillus subtilis species, Bacillus pumilus and Paenobacillus polymyxa according to MALDI-TOF MS. The research has been shown that Bacillus strains can be used successfully against bacterial speck disease of tomatoes. It was concluded that the antagonistic strains can be used in part of an integrated disease management program after side effect experiments are performed.