PromisingBacillus subtilisstrains BZR 336g and BZR 517 for biocontrol of blackcurrant againstSeptorialeaf spot under unfavorable climate conditions

Septorialeaf spot is the most serious blackcurrant disease in Western Siberia. TwoBacillus subtilisstrains BZR 336g and BZR 517 isolated in geographically distant locality (south of Russia) were evaluated for the blackcurrant disease suppression in field experiments (Western Siberia). The field trials were conducted on two cultivars differed by their susceptibility toSeptoria ribisin two consecutive years differed by environmental conditions. As a rule, plant treatment with bacterial suspensions (10(5)and 10(6) CFU/ml) significantly (P < 0.05) reduced the disease severity compared with the untreated blackcurrant plants. In some cases, the effect of bacterial strains was comparable to that of chemical fungicide Topaz, CE 0.1%. Biological control of blackcurrant disease caused byS. ribisdepended onB. subtilisstrain, concentration of bacterial suspension, plant cultivars, and weather conditions. For the first time, we showed thatB. subtilisstrains isolated in a region with warm climate effectively suppressed the main blackcurrant disease in geographically distant locality with cold climate.