Exploiting Bio-Control Agents to Manage Seedling Diseases of Soybean
by Ahmad Fakhoury, Soybean Plant Pathologist, Southern Illinois University
A bio-control agent restricts growth of the charcoal rot fungus
Over the past several years, with the support of checkoff-funding, we have built a collection of potential bio-control agents (BCAs) isolated from soybean production fields in the Midwest. Our goal is to use BCAs to improve the management of seedling diseases either by introducing them to soybean production fields, and/or fine-tuning existing management practices to enhance the activity of bio-control agents native to production fields.
In our most recent study, funded by the North Central Soybean Research Program, we tested 58 potential BCAs against seven soybean fungal pathogens and found several BCAs that restrict the growth of Fusarium virguliforme
, which causes sudden death syndrome, Fusarium graminearum
, a seed decay and damping-off pathogen, and Macrophomina phaseolina
, the causal agent of charcoal rot. In the photo we see a fungal bio-control agent coiling around the charcoal rot pathogen, one of the ways BCAs inhibit pathogen growth.
Some bio-control agents were not affected by fungicides, which opens the possibility that they could be used together with a fungicide seed treatment with minimal inhibition of their efficacy.
When monitoring the expression of soybean defense-related genes upon exposure to Fusarium virguliforme
and Rhizoctonia solani
, we found that the presence of specific BCAs induced soybean defense-related genes by as much as 16-fold compared to control plants grown without BCAs. This indicates that in addition to their antagonistic activity against plant pathogens, some of the BCAs may induce resistance mechanisms in soybean, thus providing an additional layer of protection against seedling pathogens.