The effect of endophytic bacteria Bacillus thuringiensis W65 and B. amyloliquefaciens P20 on the yield and the incidence of potato rhizoctoniosis and late blight

Chemical fungicides are chemicals used to combat late blight and potato rhizoctoniosis. However, due to repeated treatments, the resistance of plant pathogens to fungicides increases. Biofungicides serve as an alternative to chemical fungicides. The use of strains of endophytic bacteria of the genus Bacillus is promising for the development of novel biofungicides. Endophytes, being inside plants, have an advantage in interactions with the plant compared to bacteria occupying other ecological niches. In this work, for the first time, the effectiveness of experimental samples of preparations based on strains of endophytic bacteria of the genus Bacillus was established when growing potato ( Solanum tuberosum L.) varieties differing in resistance to late blight in the conditions of the North-West of the Russian Federation. It is known that the effectiveness of the use of endophytes with biocontrol activity differed in the field when growing potatoes, while the varietal responsiveness of potatoes to biocontrol agents has not been sufficiently studied. The aim of the research was to study the effect of experimental samples of preparations of endophytic bacteria B. thuringiensis W65 and B. amyloliquefaciens P20 on the yield and infection of potato plants with rhizoctoniosis and late blight. Strains of endophytic bacteria B. thuringiensis W65 and B. amyloliquefaciens P20 isolated from potatoes had antagonistic activity to phytopathogens-pathogens of late blight Phytophthora infestans (Mont. de Bary) and rhizoctoniosis Rhizoctonia solani (Kuhn.) when growing on agar media. Small-scale field experiments (2020-2021) were conducted at the experimental field of the Leningrad Research Agriculture Institute Belogorka. The experiment scheme included the following options: clean control - no treatments; chemical control - treatment with chemical fungicides: CELEST® Top, SC (Syngenta, Russia), Mankoceb, WP (AgroRus and Co., Russia), Rapid Duo,WP (AgroRus and Co., Russia), Infinito, SC (Bayer Crop Science, Germany), Buzzer, SC (CROPEX, Russia) and desiccant Golden Ring (Agro Еxpert group, Russia); biological control - BisolbiSan (BISOLBI INTER, Russia), the biofungicide based on rhizospheric bacteria Bacillus subtilis Ch-13; experimental sample of the preparation B. thuringiensis W65, experimental sample of the preparation B. amyloliquefaciens P2. Two potato varieties, Charoit (resistant to late blight) and Gusar (susceptible to late blight), were used. In the experiments, the dynamics of plant growth and development, yield and infection of potato plants with rhizoctoniosis and late blight were evaluated. Statistical treatment of the obtained results (calculations of averages and their standard errors, ANOVA analysis of variance, Duncan's test, was carried out using the Statistica 10 program («StatSoft, Inc.», USA). When inoculated with experimental samples of B. amyloliquefaciens P20 and B. thuringiensis W65, the duration of flowering of potato plants increased by 8-13 days compared to the control. The potato tuber harvest also increased by 7.9-14.6 % (p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }