Scab or Fusarium head blight (FHB) is a commercially important disease of wheat. The major causative pathogen of the disease is Fusarium graminearum, a fungus that can reduce kernels to shriveled and light tombstones thereby lowering yield and commodity quality. In addition, the tombstone kernels are loaded with mycotoxins such as deoxynivalenol (DON). The efficacies of several fungicides for managing scab were assessed under different application regimes. The treatments or application regimens included (i) a single application of Prosaro^® (6.5 fl oz/ac), ME (10.3 fl oz/ac), Miravis^® Ace (13.7 fl oz/ac), Prosaro Pro (10.3 fl oz/ac) and Sphaerex™(7.3 fl oz/ac) at early anthesis (Feekes 10.5.1), (ii)  an application of two products in sequence, starting with an application at Feekes 10.5.1 and a second application at Feekes 10.5.3, finally (iii) a single application at Feekes 10.5.3 (complete flowering). A spring wheat variety, ‘CP3188’, and a winter wheat variety, ‘Draper’, were the susceptible hosts for this endeavor. The study comprised four blocks with each treatment randomly allocated to each of the blocks as a plot. Plots were inoculated at Feekes 10.1 (visible spikelets) with F. graminearum infected corn spawn at 42g m^-2. The generalized linear model was used to analyze FHB incidence, FHB severity and FHB index on beta distribution while yield and test weight were on gaussian. Observations showed the highest FHB incidence, severity and index in untreated plots and lowest yield as well as overall kernel quality (test weight) in both wheat classes. Although scab prevalence was over 20% higher in spring wheat than in winter wheat, efficacy results revealed congruency regardless of wheat class. The sequential application scheme involving Miravis Ace at Feekes 10.5.1 and Prosaro Pro at Feekes 10.5.3 had the lowest FHB index in both wheat classes. However, statistically significant (p≤0.05) differences between the highest performing application regimen and the rest of the treatments were not observed. Negative Spearman correlations coefficients between FHB index and yield (-0.42, p<0.05) and overall kernel quality (-0.66, p<0.05) were observed in winter wheat. Similarly, the associations between FHB index and yield as well as FHB index and kernel quality were inverse, -0.53 (p<0.05) and -0.63 (p<0.05), respectively. These observations encourage wheat producers to still apply fungicides at Feekes 10.5.1 up to Feekes 10.5.3 to reduce the potential impact of scab. Further analyses will be conducted to establish mycotoxins trends once DON data becomes available.

ACKNOWLEDGEMENT AND DISCLAIMER

This is based upon work supported by the USDA Agreement No. 59-0206-0-115. This is a cooperative project with the U.S. Wheat & Barley Scab Initiative. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.