Meta-Analysis of Yield Response to Applications of Fungicides Made at Different Crop Growth Stages in Michigan Winter Wheat

Various foliar fungal diseases, as well as Fusarium head blight, are a reoccurring threat to Michigan wheat production. Fungicides are a key management tool for these diseases, and many products are efficacious. However, the timing of application is thought to be a key determinant of yield response and disease prevention. A meta-analysis of data from previously conducted small-plot fungicide trials from Michigan was performed to evaluate which fungicide application timings individually or in combination resulted in the greatest yield response across multiple years. Data from 46 trials (2007 to 2020) were utilized to examine six fungicide regimes. All regimes analyzed resulted in a statistically significant yield response, and at least an 87% probability of a positive response in future applications. The combination treatment of a Feekes 5 to 7 plus a Feekes 10.5.1 application had the highest mean yield response of 10.5 bu./ac. increase relative to the mean of the nontreated control, and the Feekes 10.5.1 application alone resulted in 7.4 bu./ac. yield response. Early season applications (Feekes 5 to 7) resulted in the lowest response, with a mean yield increase of 4.1 bu./ac. Probabilities of positive yield response and prediction intervals were calculated for all regimes to aid growers in making future fungicide application decisions.