Rhizoctonia solani and Didymella applanata impact on potato and red raspberry managed by Bacillus velezensis strains-8-3
Rhizoctonia solani and Didymella applanata impact on potato and red raspberry managed by Bacillus velezensis strains
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. Bacillus 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. 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.
In vitro antifungal activity of Bacillus strains evaluated the antagonistic properties of B. velezensis strains against the phytopathogenic fungus R. solani, isolated from infected potato tubers, and against fungus D. applanata, isolated from infected raspberry canes in Western Siberia. B. velezensis BZR 336 g and B. velezensis BZR 517 strains were used at concentrations of 104 –106 CFU/mL. The experiment was conducted using the agar block techniques. Potato seed tubers were dipped for 30 min in a BZR 336 g or BZR 517 (106 CFU mL−1 ) suspension prior to planting. In raspberry B. velezensis BZR 336 g and B. velezensis 517 strains were suspended at a concentration of 106 CFU mL−1 and used to manage raspberry disease. B. velezensis suspensions were applied at a volume application rate of 0.1 L/m2 using a hand-held Orion-6 sprayer. The control plots were treated with water. Two independent experiments were performed. Bacterial strain treatment timing was determined at the appearance of the first disease symptoms.
Potato field trials
Using B. velezensis strains reduced the disease incidence and severity on potato stems, he disease severity on the stems decreased by 79.8% under BZR 336 g and by 23.1% under BZR 517 on cv. Svitanok kievskiy, and cv. Yuna by 69.5% and 50%, respectively compared to control. In the next season disease severity was decrease to 74.1% on cv. Yuna, under the action of the BZR 336 g strain and of 50% by BZR 517.After treating Svitanok kievskiy tubers with the B. velezensis BZR 336 g strain, the disease incidence decreased by 71.5%, and on cv. Yuna by 61.1%
The bacterial strains also contributed to the potato plant growth stimulation during the growing seasons. The pre-planting treatment of potato tubers with the bacterial strains had a positive effect on the quality of the daughter tubers. Thus, the effect of the strain BZR 336 g appeared to increase with the increasing biomass of the tubers. In 2015, the effect was increased by 37.2% and by 45.0% in cv. Svitanok kievskiy and cv. Yuna, respectively. In 2016, the biomass was increased by 31.3–38.0% in both cultivars (Table 5). Tubers pre-treated with the BZR 517 strain contributed less to the yield formation. the tuber biomass increased by 42.2% (cv. Svitanok kievskiy) and by 26.5% (cv. Yuna) compared with the control
Red raspberry field
B. velezensis strains were able to reduce the disease incidence. 69.3% reduction in disease incidence 4 weeks after BZR 517 treatment on cv. Kirzhach; in cv. Kolokolchik, the reduction was 50.0%. In 12 weeks, B. velezensis reduced this value by 46.4% in cv. Kirzhach, and by 59.7% in cv. Kolokolchik. Reduction in disease severity was observed using the B. velezensis 517 strain (69.1% on cv. Kirzhach and 47.8% on the resistant cv. Kolokolchik. Spur blight severity decreased by 54.1% in cv. Kirzhach, and 60% in cv. Kolokolchik compared to the control. Two B. velezensis strains stimulated the growth of the potato plant, which contributed to the plant productivity. It should be noted that biocontrol methods are very promising sources of plant disease control in organic farming. Some B. velezensis strains are used in organic agriculture as an alternative to chemical pesticides. Organic farming systems are more profitable and environmentally friendly; they deliver foods that contain less (or no) pesticide residues when compared with conventional farming. This is important for potato and raspberry planted in small farms.
Reference:
Asaturova, A., Shternshis, M., Tsvetkova, V., Shpatova, T., Maslennikova, V., Zhevnova, N. and Homyak, A., 2021. Biological control of important fungal diseases of potato and raspberry by two Bacillus velezensis strains. Peer J, 9, p.e11578.
