The Optimization of Grain Crops’ Phytosanitary Condition with Associative Rhizobacteria Application

The effectiveness of associative rhizobacteria’s influence on the intensity of soft wheat and triticale diseases’ development was studied. According to the experimental scheme, seeds were soaked and plants were sprayed twice with a working fluid containing rhizobacteria strains of Bacillus subtilis 124-11, Sphingomonas sp. K1B, and Pseudomonas fluorescens SPB2137 (titer 10 8 –10 9 cells/mL) and other variants with combined treatment with a liquid organomineral composition Batr Gum. In the control, plants were treated with water and Batr Gum (by 10 mL/L of water). The biopreparations' influence on disease development was investigated using generally accepted accounting scales and additional phytopathological indicators. The Bacillus subtilis strain 124-11 had the maximal effectiveness against yellow and brown rust of wheat, while Sphingomonas sp. K1B had that against triticale rusts. In particular, the treatment of the local cultivar Leningradskaya 6 with Bacillus subtilis 124-11 led to a decrease in the development of yellow rust by 12%, the pustules number by 47%, the strip length by 41%, the pustule area by 39%, the brown rust development by 9%, the pustules number by 50%, and the pustule area the by 40%. After the Dua, k-828 cultivar treatment with the Sphingomonas sp. K1B strain, a decrease in the plants’ affection by brown rust was observed by 13%, the pustules number decreased by 59%, and the pustule area by 52%. A significant decrease in the powdery mildew development on soft wheat and a decrease in the number of spots with plaque were recorded when using the Sphingomonas sp. K1B strain on cultivars: by 12% (79.4%) in Leningradskaya 6, 19% (72.5%) in Ajeeba, 13% (87.2%) in Trizo, and 3% (60%) in Sudarynya. On the soft wheat cultivar Sudarynya and triticale cultivars Aist Kharkovskiy and Dua, a decrease in helminthosporiotic root rot was revealed when using associative rhizobacteria; the maximal decrease in the disease development (by 32%) was noted when using the strain Sphingomonas sp. K1B. When bacterial strains were used combined with the organomineral fertilizer Batr Gum, the development of powdery mildew and yellow rust was much slower than when they were used separately, while the greatest effectiveness against these diseases (by 31 and 91%) was revealed in the “Batr Gum + Pseudomonas fluorescens SPB2137” experimental variant.