Control, by microbial seed treatment, of damping-off caused by Pythium sp on canola, safflower, dry pea, and sugar beet

Indoor and field experiments were conducted to determine the effects of seed treatment with strains of rhizosphere bacteria collected from southern and central Alberta for control of damping-off of sugar beet, canola, safflower, and dry pea caused by Pythium sp. Indoor experiments showed that 12 strains of rhizobacteria, including Pseudomonas fluorescens (708, 1-2, 1105, 1809, 2106, and 2202), Bacillus cereus PS1, Bacillus megaterium SB6, Arthrobacter sp. 2101, Pantoea agglomerans (909, 2-2), and Erwinia rhapontici A123, were effective in controlling damping-off of sugar beet. These strains varied in their ability to suppress mycelial growth of Pythium sp. group G, in vitro, and in their ability to secrete extracellular protease. Strains of Pseudomonas fluorescens (708, 1-2, 2202), B. cereus PSI, E. rhapontici A123, and Pantoea agglomerans 2-2 were effective seed-treatment agents for control of damping-off of canola, safflower, dry pea, and sugar beet in fields naturally infested with Pythium spp., although there were some differences in efficacy among the strains for each of the crops. Seed treatment with combination of Pseudomonas fluorescens 708, B. cereus PS1, or E. rhapontici A123 and the fungicide Thiram(TM) did not improve dry pea emergence compared with the fungicide control under field conditions.