In vitro and in vivo studies were conducted to assess the efficacy of the two microbial chitinases Chi I (from Streptomyces sp.) and Chi II (from Serratia marcescens) on Didymella applanata (Niessl.) Sacc., the fungus which causes spur blight of raspberry (Rubus idaeus L.). D. applanata was isolated from canes of diseased raspberries in a plantation in Novosibirsk, Russia. In vitro, the effective concentration of Chi I that reduced the growth of D. applanata was 0.4 U/ml (p=0.05), but Chi II had no influence on the growth of the fungus in medium. In inoculation experiments on raspberry canes, both chitinases at the rate 0.5 U/ml reduced fungal development. In plantation where canes were inoculated after spraying with chitinase, fruiting bodies of fungus failed to form in all enzyme treatments, whereas a significant number of these fungal fruiting bodies (12.8 per cm 2 ) developed in control treatments lacking chitinases spraying. The chitinases reduced the size of lesions and limited the infection of internal tissues of canes. Field testing of Chi I under natural conditions showed a significant suppression of the independent spur blight. These studies form the basis for further evaluation of ecologically benign control measures for raspberry spur blight.

The influence of Siberian strains of bacteria Bacillus spp. on the strawberry gray mold causative agent and plant resistance to the disease in three seasons differing in growing conditions has been studied. Bacterial strains B. subtilis, B. amyloliquefaciens, and B. licheniformis suppress the development of the phyto pathogenic fungus B. cinerea in vitro and in vivo. In addition to the antifungal action, bacterial strains show a positive effect on the growth and development of strawberry plants, indicating multifunctional properties of Siberian strains Bacillus spp.

Stem canker and black scurf caused by Rhizoctonia solani are the important diseases in potato, while spur blight caused by Didymella applanata 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 Bacillus velezensis 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 B. velezensis strains on two plant cultivars differed by the disease resistance. The degree of B. velezensis influence on disease incidence and severity depended on the bacterial strain, the protected plant, and its cultivar. We also demonstrated that two B. velezensis 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 B. velezensis 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 B. velezensis strains potential for use as biological control agents against R. solani on potato, and against D. applanata on red raspberry.

The mutual functional dependence in the three component system Bacillus thuringiensis-Rhizoc tonia solani-Solanum tuberosum is shown. Suppression of the rhizoctonia potato disease due to the treatment of tubers with entomopathogenic bacteria Bacillus thuringiensis subsp. Darmstadiensis (BtH 10 ) is demon strated. In vitro inhibitory activity of BtH 10 towards R. solani exceeded 80%. Field testing is carried out on two potato cultivars of different ripeness groups in 2013-2014. The rhizoctonia disease severity in stems, stolons, and new tubers decreases significantly due to BtH 10 treatment. Together with biological control of R. solani, BtH 10 promoted plant growth, increasing germinating capacity and stem height and number. The polyfunc tional activity of the BtH 10 bacteria contributes to the improvement of potato productivity. Fig. 3. Height of plants (LSD 05 by strain and cultivar = 1.5) and number of stems per potato plant (LSD 05 by strain and cultivar = 0.25) on average for 2 years. (1) Lyubava cultivar; (2) Lugovskoy cultivar; (a) control; (b) treatment of tubers with BtH 10 .

In vitroandin vivostudies were conducted to estimate the efficacy of the two microbial formulations based onBacillus subtilisCohn. andPseudomonas fluorescensMig. on the fungusDidymella applanata(Niessl.) Sacc., the causal agent of red raspberry (Rubus idaeusL.) spur blight.In vitro, both bacteria reduced the growth ofD. applanata. In inoculation experiments with raspberry canes in two cultivars with different susceptibility toD. applanata, these antagonistic bacteria suppressed fungal development by reducing the lesions area and the number ofD. applanatafruiting bodies. Field trials of two biological formulations under natural conditions showed a significant suppression of the disease.B. subtilisandP. fluorescensincluded in the formulations revealed antagonistic activity towardsD. applanatathat depended on the red raspberry cultivar and weather conditions. In all cases,B. subtilisshowed better results thanP. fluorescensin biocontrol of the raspberry spur blight. This study demonstrated for the first time the ability of the biocontrol agentsB. subtilisandP. fluorescensto suppress red raspberry cane spur blight, a serious worldwide disease.