BACTERIAL STRAINS ANTAGONISTIC TO PYRENOPHORA TRITICI-REPENTIS IN VITRO DEMONSTRATE DIFFERENT EFFICACY ON WHEAT SEEDLING IN GREEN HOUSE

Yellow leaf spot is a wide spread diseases of soft and hard wheat. Numerous publications and the authors' own research show that its epiphytotics occur in different countries (Australia, Canada, USA, India, England, Belgium, Romania, Czech Republic, Kazakhstan) with crop losses reaching 65 %. In Russia the disease is most common in the North Caucasus. Development and application of new high-performance environmentally friendly biological products is regarded as one of the most effective biologized approach to wheat protection against the disease. In searching potential bacterial agents for use as protective means, their in vitro antagonistic activity should be accompanied by the ability to provide effective protection for seeds and seedlings. Herein we studied the repression of yellow spot development during early stages of plant vegetation in a greenhouse as influenced by the bacterial strains which were in vitro antagonistic to P. tritici-repentis (Died.) Drechsler. Winter wheat cultivar Bat’ko susceptible to the pathogen was used as test plant. Six isolates of the Bacillus family (Bacillus sp. BZR 18, B. subtilis BZR 336 s, B. subtilis BZR 336 g, B. subtilis BZR 436, B. subtilis BZR 517, B. licheniformis BZR 59), as well as Ochrobactrum sp. BZR 417 from the collection of All-Russian Research Institute of Biological Plant Protection were used as candidate bio agents. For comparison, liquid Fitosporin-M was used as a biological preparation (LLC Scientific Innovation Enterprise «BashInkom», Russia) and Prozaro emulsion concentrate was used as a chemical fungicide («Bayer CropScience», Germany). Liquid cultures of antagonistic bacterial strains were applied in three modes, namely before inoculation (prophylactic treatment), at early signs of the disease (on the day 3 after inoculation) and by their combination. All treatments were performed with inlaying and without inlaying grain with liquid bacterial culture. All studied bacterial strains except Ochrobactrum sp. BZR 417 showed considerable biological efficacy of leaf spot inhibition. The Bacillus sp. BZR 18 and B. subtilis BZR 517 were the most inhibiting strains which repressed leaf spot development at 68.5 to 83.0 % and 55.6 to 64.0 % rate, respectively, in all variants except treatment at early signs of the infection without inlaying grains when the efficiency was 26.8 and 35.9 %, respectively. B. licheniformis BZR 59 provided for 52.6 to 68.9 % leaf spot inhibition. Liquid culture of B. subtilis BZR 336 g strain ensured efficiency from 51.5 to 58.3 % in all variants except a preventive treatment without inlaying grain when the efficiency was 40.9 %. B. subtilis BZR 336 s, if used at early signs of infection with inlaying grain and in combination of prophylactic treatment with application at early signs of infection and inlaying grain, caused 60.2 and 60.3 % leaf spot repression; in other cases a 14.7 to 44.3 % repression was observed. BZR 436 B. subtilis effectiveness was from 28.4 % under preventive treatment with preliminary grain inlaying to 73.4 % under preventive treatment together with application at early signs of infection and inlaying grain. The efficiency of Ochrobactrum sp. BZR 417 strain does not exceed 45.4 % in all variants. Depending on antifungal activity of the bacterial agent, a combination of grain pre-treatment, prophylactic treatment and treatment at early signs of infection proved to be the most effective.

• Asaturova A.M.
• Kremneva O.Yu.
• Volkova G.V.
• Zharnikova M.D.

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