Indigenous Rhizobium isolates from naturally-formed bean root nodules were antagonistic to some of the root rotting pathogens of snap bean. Rhizobium isolates inhibited the radial growth of Fusarium species in dual culture agar plate tests but were not inhibitory to Rhizoctonia solani or Pythium isolates. With one exception, all indigenous Rhizobium isolates showed some degree of antagonism towards F. solani f. sp. phaseoli in vitro. The level of in vitro inhibition depended upon the agar plate technique utilized. A high level of in vitro inhibitory activity was recorded in 38% of the Rhizobium isolates tested where wide zones of inhibition formed between the test isolates and persisted for more than 1 week. A similar inhibitory effect of 8/17 nodulating Rhizobium isolates to Fusarium root rot of snap bean was observed in growth pouch experiments. Protection of bean plants from severe Fusarium root rot occurred in combinations where the inoculum concentration of Rhizobium (10\ 106 cells/pouch) was equal to or greater than the inoculum concentration of F_. solani (10² , 10⁴ spores/pouch). Ten Rhizobium isolates, which were highly antagonistic in vitro, had no apparent inhibitory effect on Fusarium root rot in vivo. Two Rhizobium isolates, RCC324 and RCC607, inhibitory to Fusarium root rot did not reduce Rhizoctonia root rot of bean. Soil experiments supported the results of growth pouch experiments whereby inoculation of bean seed with a high concentration of Rhizobium (RCC106 at 10⁸ cells/seed) effectively reduced bean root rot incited by a low inoculum potential of the pathogen, F. solani (inoculum: soil, 1:10⁴ or 1:120). These results indicated the potential exists for field control of Fusarium root rot of snap bean by a highly antagonistic nodulating isolate of Rhizobium. / Land and Food Systems, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/22547 |
| Date | January 1981 |
| Creators | Smulders, Andrea Joanne |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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