Strains of soil microorganisms promising for the creation of a complex plant protection product against mycoses and harmful insects

Abstract

We evaluated the antagonistic activity of 23 strains of Bacillus spр. against phytopathogenic fungi Fusarium oxysporum, F. culmorum, F. moniliforme, Cladosporium herbarum, Alternaria alternata and Aspergillus niger. The antagonistic activity was tested by agar diffusion (the method of blocks). For determining the influence of bacteria on barley plants , ardent seeds were treated by cultural liquid (dilution 1 : 10) for 2 hours and germinated in Petri dishes on moist filter paper. The fungistatic effect of Bacillus sрp. separately and in combination with entomopathogens (in equal ratio) was determined by the level of inhibition of the fungi Fusarium spp. on a solid nutrient medium with 5% of the culture liquid. Insecticidal activity of microorganisms was determined in the model experiments by the percentage of death of the caterpillar Archips podana Scop. Strains of Bacillus sp. KMB-3 and Bacillus sp. KMB-6 inhibited the growth of all test cultures (zones of growth inhibition 11.4–30.6 and 11.5–29.4 mm, respectively). We established the absence of antagonism between selected strains and entomopathogenic bacteria Bacillus thuringiensis IMB-7186, fungi Beauveria bassiana IMB-F-100043. We found that treatment of barley seeds with culture liquids of Bacillus sp. KMB-3 and Bacillus sp. KMB-6 didn’t have a negative effect on the morphometric indices and dry weight of seedlings. We established that the highest percentage of growth inhibition of F. culmorum IMB-F-50716 was provided by a complex of Bacillus sp. KMB-3, B. bassiana IMB-F-100043 and B. thuringiensis IMB-7186, whose action was at the same level as the action of monoculture Bacillus sp. KMB-3 (85.4% and 84.7%, respectively). The highest percentage inhibition of growth of F. oxysporum ІМВ-F-54201 was provided by a complex of strains of Bacillus sp. KMB-3 and B. bassiana IMB-F-100043, whose effect was slightly inferior to that of the monoculture Bacillus sp. KMB-3 (68.4% and 75.1%, respectively). The insecticidal activity of complexes Bacillus sp. KMB-3, B. bassiana IMB-F-100043, B. thuringiensis IMB-7186 or Bacillus sp. KMB-6, B. bassiana IMB-F-100043, B. thuringiensis IMB-7186 insignificantly differed from that of the complex entomopathogens B. bassiana IMB-F-100043 and B. thuringiensis IMB-7186 (71.1%, 73.3% death versus 80.0%). The selected microbial complexes can be considered as promising for the development of a preparation for the protection of plants against fungal diseases and harmful insects.