Are there benefits to early fungicide applications on wheat?
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
The short answer is yes and no. Results were mixed in trials we conducted last year, depending on variety or level of disease present. For the last couple of years, some chemical companies have promoted: 1) the use of a reduced rate of fungicide at the same time that herbicide applications are made to winter wheat, or 2) an application of copper at the same time that herbicide applications are made to winter wheat. To help answer the question about whether there were yield or quality improvements associated with early fungicide applications to wheat that would translate into economic benefits, last year we evaluated early treatments alone or in combination with treatments at other timings in three separate trials. Several treatments were statistically significant. Other treatments were not statistically significant (p=0.05) but still would have been profitable, depending on the dollars/per bushel received (see economic comparisons charts). Other treatments were not statistically significant, and would not have been profitable, using the average sample costs we calculated for application, fungicides and adjuvant.
The first trial used ‘Caledonia’ white wheat, and was planted at the Clarksville research station. We evaluated reduced rates of Headline, and Stratego at Feekes 5 (stem elongation),and Kocide at Feekes 5; single applications of Prosaro, Proline, or Caramba at Feekes 10.5.1 (flowering); and combinations of Kocide (Feekes 5) + Prosaro (Feekes 10.5.1), Stratego (Feekes 5) + Prosaro ( Feekes 10.5.1), and Headline ( Feekes 5) + Caramba (Feekes 10.5.1). In this trial, disease pressure was low. For powdery mildew, and Septoria leaf blotch, disease never reached above the flag leaf -1. Plots were rated for powdery mildew and Septoria blotch using a scale of 0-9, with 0 = no disease, and 9 = disease on flag leaf greater than 20 percent. Compared with the untreated, powdery mildew and Septoria were significantly reduced by Stratego at Feekes 5 (stem elongation), Stratego at Feekes 5 + Proline at Feekes 10.5.1 (beginning of flowering) and Headline at Feekes 5 + Caramba at Feekes 10.5.1. Leaf rust was present at low levels, but was not rated. Although there were significant differences among treatments for head blight incidence, severity and field severity, there were no significant differences in DON. DON values ranged from 0.13-0.34 ppm, all well below the value that would result in discounts. None of the early treatments tested resulted in yields that were significantly different from the untreated control. One combination treatment, Stratego at Feekes 5+ Proline at Feekes 10.5.1(flowering) and Caramba at Feekes 10.5.1(flowering) resulted in significantly higher yields.
The next two trials used five varieties of winter wheat – ‘D8006’, ‘Crystal’, ‘Jewel’, ‘Hopewell’ and ‘Red Ruby’ (three white, two red) planted at two different locations, Sandusky and Clarksville. Treatments varied somewhat by location. At Sandusky, treatments included a half rate of Tilt (Feekes 5), a full rate of Headline (Feekes 8) a tank mix of Folicur and Proline at flowering, and a combination treatment (“disease free”) that included all three application timings. Disease pressure from Stagonospora leaf and glume blotch at Sandusky was high. Disease pressure from other diseases including powdery mildew, head blight and leaf rust was low. DON values at both locations were all below 1.0 ppm, and would not have resulted in any discounts.
At Clarksville, the treatments were a half rate of Tilt (Feekes 5), + full rate of Headline (Feekes 8) a full rate of Headline alone (Feekes 8), Proline at flowering, and a combination treatment (“disease free”) that included all three application timings. Overall disease pressure at Clarksville was low. For Hopewell’ and ‘Red Ruby’ all fungicide treatments significantly reduced powdery mildew and leaf rust compared with the control. All fungicide treatments except Proline at Feekes GS 10.5.1 reduced septoria blotch disease severity compared to the control. White wheats responded a little differently. There were significant differences among treatments for powdery mildew on ‘D8006’ and ‘Jewel’ and on all three varieties for Septoria blotch. All fungicide treatments resulted in less leaf rust than the untreated on ‘Crystal’. FHB incidence was significantly lower in ‘D8006’ treated with Tilt at FGS 5 + Headline at FGS 8 + Proline at FGS 10.5.1 compared with Headline at FGS 8 alone, but there were no differences in FHB incidence for the other varieties. There were no significant differences in FHB severity, index, or DON in any varieties for any treatments. None of the treatments at either location resulted in statistically significant differences in yield, although some of the treatments still would have been profitable. With the high level of foliar disease (Stagonospora leaf and glume blotch) at Sandusky, fungicide application resulted in a net increase in profits much more frequently than at Clarksville, where there was not much disease.
View PDF of Wheat Fungicide Comparisons.