Efficacy of New Local Bacterial Agents against Pyrenophora tritici-repentis in Kuban Region, Russia

The phytopathogenic fungus Pyrenophora tritici-repentis is a causal agent of tan spot. Antagonistic microorganisms can be used as a non-chemical alternative treatment against the tan spot of wheat. Bacillus velezensis BZR 336 g and BZR 517 stains were selected as the most active microorganisms and potential biocontrol agents. We found that B. velezensis strains BZR 336 g and BZR 517 exhibited antagonistic activity against P. tritici-repentis Kr-15/2016 in vitro: they inhibited mycelium growth by 72.4-94.3% and caused its degenerative changes. Treatment of seeds and plants with strains BZR 336 g and BZR 517 provided a biological efficiency of 31.2-38.4% against tan spot, while artificial inoculation of plants provided only 28.4-43.8% biological efficiency. Treatment of seeds and plants with BZR 336 g and BZR 517 in a three-year field trial demonstrated 24.6-50% biological efficiency. BZR 336 g and BZR 517 provided 5.0-7.6% additional yield. We conclude that BZR 336 g and BZR 517 are promising options for novel bioproducts that can control P. tritici-repentis tan spot.