Biological control of snow mould (Microdochium nivale) in winter cereals by Pseudomonas brassicacearum, MA250

Seed lots of winter wheat and rye, naturally infested with Microdochium nivale and Fusarium spp., were treated with an isolate of Pseudomonas, which was recovered from roots of Brassica napus. Seeds were treated with bacterial fermentate and dried before sowing or they were directly sprayed in the furrow-opener at the moment of sowing. Besides field experiments, parallel climate chamber bioassays were performed to assess the effect of bacterial treatment on snow mould caused by seed-borne M. nivale and Fusarium spp. The biocontrol effect was assessed by plant density counts and by measuring yield. Significant biocontrol activity, measured by plant density counts, was detected both in field and climate chamber experiments sown with wheat. Biocontrol effect after spray application at sowing was less pronounced, although a slight increase in plant density was observed. The cell concentration required to obtain adequate biocontrol effect was 10⁹ CFU per ml for the dose used. The bacterial isolate was identified by 16S rDNA sequencing and biochemical tests as a Pseudomonas brassicacearum strain.