Issue No. 1, Article 6/March 21, 2008
Early Foliar Fungicide Applications for Wheat
Foliar fungicides on all crops in Illinois have certainly been a topic of discussion throughout the winter months. Now that spring is approaching, winter wheat will be one of the first crops in the state to possibly encounter a fungicide. A variety of diseases, including rusts, Septoria/Stagonospora complex, tan spot, and head scab, can certainly reduce yield and quality of susceptible wheat varieties when conditions are favorable.
Additional articles on foliar fungicides for wheat will follow in the upcoming issues; here I focus specifically on early applications of fungicide (around Feekes 5 or 6). Early applications of reduced-rate fungicides are being discussed and promoted in some regions of the state. The possible benefit of applying fungicides this early would be that they could potentially be applied with an herbicide. The potential downfall is that the fungicide may not be as effective as a single application later in the season for protection of the flag leaf.
Results from trials conducted from 2004 to 2007 in Dr. Bryan Young's research program at Southern Illinois University at Carbondale and Belleville indicate that full-rate fungicides applied at Feekes 9 or 10 show a more consistent benefit than half-rate fungicides applied at Feekes 5. Unless leaf, stem, or stripe rust is already apparent at Feekes 5, an application this early may have less benefit than at Feekes 9.
Research by Dr. Young at Carbondale in 2004 and 2005 evaluated Headline applied at 3 fluid ounces per acre at Feekes 5 and at 6 fluid ounces per acre applied at Feekes 9 (Figures 1 and 2). This study was conducted over 18 to 25 wheat varieties per year. In 2004, only 6 out of 25 varieties had significantly greater yield than the untreated check when Headline was applied at Feekes 5; however, 20 out of 25 had significantly greater yield when Headline was applied at Feekes 9. In 2005, there were very few significant yield differences between untreated and Headline-treated plots, regardless of the rate and application timing. Foliar disease pressure was much greater in 2004 compared to 2005, which is likely why Headline fungicide increased yield on several varieties in that year of the trial.
Effect of Headline fungicide applied at different rates and timings to twenty-five wheat varieties at Carbondale, IL in 2004. This research trial was conducted by Dr. Bryan Young, Southern Illinois University.
Effect of Headline fungicide applied at different rates and timings to eighteen wheat varieties at Carbondale, IL in 2005. This research trial was conducted by Dr. Bryan Young, Southern Illinois University.
Carl A. Bradley