Evaluating Winter Wheat Spatial and Temporal Flowering Variation for Managing Fusarium Head Blight.

Fusarium head blight is a significant problem in many U.S. wheat production systems. Although infection of the wheat spike is possible from heading into grain filling, the primary risk time is during flowering as infection rate is highest via the anthers. Therefore, the recommended management practice is to apply one fungicide application at the time of flowering, but efficacy is highly variable. The objectives of this work are to examine the spatial and temporal variability of winter wheat phenology for the developmental stages of heading through early grain filling. The evaluation is based on data from an experiment on a 100-ha of a farm located in eastern Colorado, other plot experiments, and the literature. Spatial and temporal variation is a function of within shoot, within plant, within small areas, and within large areas (from varying soils and topography) that can lead to great variability within the field. This variability differs depending on the year, but in years of high variability it is likely to reduce the efficacy of the fungicide application.