|WEEMS, JAVE - University Of Illinois|
|BOND, JASON - University Of Illinois|
|AMES, KEITH - University Of Illinois|
|BRADELY, CARL - University Of Illinois|
Submitted to: Canadian Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2015
Publication Date: 12/29/2015
Citation: Weems, J.D., Haudenshield, J.S., Bond, J.P., Hartman, G.L., Ames, K.A., Bradely, C.A. 2015. Effect of fungicide seed treatments on Fusarium virguliforme infection of soybean and development of sudden death syndrome. Canadian Journal of Plant Pathology. 37:435-447.
Interpretive Summary: Interest in using fungicide seed treatments to control a fungal disease in soybean called sudden death sndrome has increased recently. Previous research has shown that early root infection by the fungus is critical for disease development. It may be possible for fungicide seed treatments to inhibit early infection thus limiting the disease later in the season. In our study, none of the fungicide seed treatments evaluated in the field consistently inhibited fungal infection or reduced sudden death syndrome severity in soybean. It was proposed that soybean growers should continue to utilize other practices for SDS management until new seed treatments with consistent efficacy in controlling the disease are available.This research is important to scientists interested in disease management of soil borne diseases in soybean.
Technical Abstract: Sudden death syndrome (SDS), caused by Fusarium virguliforme (Fv), is a major yield-limiting disease of soybean in North America. Infection of soybean seedling roots by Fv results in severe root damage; therefore, fungicide seed treatments could potentially reduce these early-season infections and reduce severity of foliar symptoms that typically occur later in the season. Multiple fungicide seed treatment combinations were evaluated for their effects on Fv infection, DNA concentrations in roots, soybean root development, and SDS development in the field, greenhouse and laboratory trials. Several seed treatments decreased root disease symptoms compared to the non-treated inoculated control in the laboratory assay, and the biological seed treatment, Bacillus pumilus, significantly decreased seedling development and increased SDS root disease compared to the non-treated inoculated control. In the greenhouse, Fv DNA concentrations in roots were reduced by a treatment combining mefenoxam + thiophanate-methyl + azoxystrobin + Bacillus pumilus + prothioconazole + fludioxonil compared to the non-treated control; however, the reduction in Fv DNA did not improve root growth or decrease SDS symptoms compared to the non-treated control. Field trials were conducted in Valmeyer, IL in 2008 and in Urbana, IL in 2008 and 2009. Seed treatments had no effect on the concentration of Fv DNA in soybean roots and had very little effect on root morphology. At the Valmeyer location, most seed treatments significantly decreased SDS symptoms compared to the control. In summary, no consistent, significant effects of the seed treatments evaluated in this study on SDS or Fv root infection were observed. Therefore, soybean growers should continue to utilize other practices for SDS management until new seed treatments with consistent efficacy in controlling SDS are available.