Effect of Seed Treatment with Novel Strains of Trichoderma Spp. on Establishment and Yield of Spring Wheat.

Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe is a wide spread and destructive disease of wheat in Canada.  Seeds obtained from FHB affected fields may lead to poor stand establishment as a result of reduced seed vigor. The objective of this study was to evaluate the efficacy of selected strains of Trichoderma spp. as seed treatments for controlling the seed-borne phase of FHB. Twenty-two strains of Trichoderma spp. that were recovered from roots of seedling plants in agricultural soil were examined for their antagonistic effects on mycelium growth of F. graminearum in dual culture assays.  Six strains, including Trich12, TrichC06, TrichC39, TrichC70, TrichPine and TrichMM7, that showed >50% inhibitions were selected and used as seed treatments to further assess the their abilities in reducing root rot severity and enhancing seedling emergence, growth and yield in field trials in 2008, 2009 and 2011, using wheat seed contaminated with F. graminearum.  Over the three years, all six strains significantly reduced root rot severity and increased yield, three stains increased emergence and four strains increased plant dry weight, compared with the untreated controls. TrichC70 was the only strain that showed a significant improvement to all four parameters, increasing emergence by 10.9%, dry weight by 51.7%, and yield by 11.0% and reducing root rot severity by 51.7%. These effects were not significantly different from that of the registered fungicide Vitaflo-280 used as positive controls in the field trials. The results indicate that Trichoderma stain TrichC70 may be used as an alternative to fungicide seed treatments to control the seed-borne phase of FHB.