DisplayTitle

In the previous symposium on this topic in 2009, the main focus of my presentation was on the effects of strobilurin fungicides on various physiological processes in treated plants. Today’s presentation will concentrate on elucidation of yield benefits from strobilurin fungicides as influenced by plot size. Data over three years, from independent and Syngenta small-plot trials, have indicated a 2-3 Bu/A increase in yield in strobilurin-treated plots over untreated controls. These results were similar to those reported by University reseaerchers as non-beneficial to growers. By contrast, data from commercial plots (≥ 20 acres) over the same period have indicated yield benefits of 10-15 Bu/A. To explore these discrepancies in the magnitude of yield benefits, Syngenta conducted trials in 26 locations in 2011 across the corn-belt with 2 hybrids per location. To eliminate border effects, these were large plot trials (5 acres per hybrid). The yield results from these 52 hybrid-by-location replications were consistent with earlier data from commercial-size un-replicated trials. Quadris at V5, Quilt Xcel at R1, or the combination of the two provided average yield benefits of 5.2, 11.2, and 14.2 Bu/A, respectively, over the untreated control. These data from 2011 suggest that the earlier results from commercial-size plots were a good indicator of yield benefits from the application of Quadris and/or Quilt Xcel at the recommended timings. By inference, yield data from small plot trials may be less accurate indicators of the benefits of strobilurin fungicides on commercial corn production in the relative absence of disease.<p><p>Keywords: