Biological control of important fungal diseases of potato and raspberry by two strains.

Stem canker and black scurf caused by are the important diseases in potato, while spur blight caused by is a major disease in red raspberry. In Western Siberia, both crops are grown predominantly in small-scale farming that requires maximal usage of biological products for plant protection instead of chemicals. We evaluated two promising strains BZR 336 g and BZR 517 isolated in the south of Russia (45°1'N, 38°59'E) for their biological control potentials against the potato and red raspberry diseases under the more severe weather conditions of Western Siberia (55°1'N, 82°55' E). We tested two techniques to apply biocontrol agents: (1) coating the seeds (potato tubers) and (2) spraying over the plants (raspberry canes). In each case, we estimated strains on two plant cultivars differed by the disease resistance. The degree of influence on disease incidence and severity depended on the bacterial strain, the protected plant, and its cultivar. We also demonstrated that two strains significantly stimulated plant growth of potato, which contributed to the plant productivity on both cultivars. The BZR 336 g strain affected the potato productivity more than the BZR 517 strain. Under the influence of both bacterial strains, raspberry yield was significantly higher compared to the control on the susceptible cultivar. These findings indicated that two southern strains had proved their efficacy as biological control agents in the control of the serious fungal infection of potato and raspberry plants under the more severe ecological conditions of Western Siberia. For the first time, we demonstrated strains potential for use as biological control agents against on potato, and against on red raspberry.