Effect of fungicidal seed treatments on the emergence, development, and grain yield of Fusarium graminearum-infected wheat and barley seed under field conditions

May, W. E., Fernandez, M. R. and Lafond, G. P. 2010. Effect of fungicidal seed treatments on the emergence, development, and grain yield of Fusarium graminearum-infected wheat and barley seed under field conditions. Can. J. Plant Sci. 90: 893-904. In areas affected by Fusarium head blight, growers are concerned about planting seed infected with Fusarium graminearum. This study evaluated the effects of commercially available fungicidal seed treatments on the emergence, development, and grain yield of Fusarium-infected seed of common wheat (Triticum aestivum L.), durum wheat [T. turgidum L. ssp. durum (Desf.) Husn.], and barley (Hordeum vulgare L.). Infected seedlots were treated with 12 combinations of seed-applied fungicides; nine of these are currently registered in Canada. In addition, five experimental products were used. The experiment was conducted over three years (2003-2005) at four locations in eastern Saskatchewan. Common wheat was grown in all 3 yr, durum wheat in 2003 and 2004, and barley in 2004 and 2005. In the seedlot with the highest level of F. graminearum infection (63%), fungicidal seed treatments improved plant emergence and grain yield. In the three seedlots with moderate levels of infections (25 to 35%), seed treatments improved emergence, but did not significantly affect grain yield. In four seedlots with lower levels of F. graminearum infection (5 to 10%) seed treatments had no significant effect on emergence or grain yield. By adjusting the seeding rate, based on percent germination needed to achieve a target plant density of 200 plants m(-2) reductions in grain yield were prevented except in the seedlot with the highest level of infection. However, actual plant density was often below the target plant density, which indicates that field seedling mortality was greater than the 5% assumed when determining the seeding rates. Seed treatments did not significantly affect the test weight in the harvested grain. In conclusion, fungicidal seed treatments did not consistently improve the agronomic performance of F. graminearum-infected common wheat, durum wheat, or barley seed in eastern Saskatchewan.