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The influence of abiotic and biotic factors on yield loss has usually been analysed separately without considering their interactions. Consequently, the main objective of this study was to investigate the relationship between FHB index, Fusarium-damaged kernels (FDK) and yield loss, while considering effect of climatic conditions and cultivar resistance/susceptibility to FHB as a coherent whole. The study was conducted over two growing seasons (2013/2014 and 2014/2015), using 25 commercial winter wheat cultivars. Fungicide-sprayed and non-sprayed treatments were applied, while corn kernels infected with F. graminearum provided an artificial source of FHB inoculum. Average FHB index of 25 cultivars in 2014 (31%) and FDK (15%) differed significantly from FHB index (10%) and FDK (5%) in 2015. Variability in FHB index and FDK was more uniformly related with yield loss of moderately resistant than it was in susceptible/moderately susceptible cultivars. Correlation of FHB index and FDK also differed between susceptible/moderately susceptible (r = 0.362, p = 0.035) and moderately resistant cultivars (r = 0.732, p = 0.001). Yield loss of susceptible/moderately susceptible cultivars caused by FHB differed less uniformly than it did in moderately resistant ones. Different responses of susceptible/moderately susceptible cultivars on FHB pressure in the same environment indicated that there might be a threshold of pathogen pressure below which a cultivar will not response with significant yield loss in cases where other requirements relevant to exhibit the cultivar's yield potential are met.

Factors influencing Fusarium head blight (FHB) occurrence and yield losses in winter wheat have extensively been studied through the years; however, reports on the relationship between FHB traits and yield are conflicting. In addition, studies neglected the relationship between FHB traits and thousand-kernel weight (TKW). This study evaluated the variability in the relationship between FHB traits, TKW, and yield under field conditions, using 40 commercial winter wheat cultivars differing in resistance/susceptibility to FHB. In general, the FHB index had greater relation to yield, while Fusarium-damaged kernels (FDK) was more related to TKW. The relationship between yield, TKW, FHB index, and FDK was also determined by resistance/susceptibility of winter wheat cultivars. Fusarium-damaged kernels influenced yield more in moderately resistant (R2 = 43 %) than in susceptible/moderately susceptible cultivars (R2 = 27 %). The influence of the FHB index on TKW was weak (R2 = 9 %) in susceptible/moderately susceptible cultivars and in moderately resistant ones (R2 = 1 %). The potential to predict TKW from yield under pathogen pressure was limited due to the moderate-to-positive correlation between yield and TKW (r = 0.349, p < 0.001). This study provides insights into factors that influence TKW under FHB pathogen pressure and gives direction to more efficient and reliable investigations on grain resistance toward FHB.

Reports on the effectiveness of Fusarium head blight (FHB) control measures do not follow the same pattern in different regions, and the combined effects of abiotic and biotic factors on FHB are not fully understood. Consequently, the main objective of this study was to examine divergence in susceptibility reactions of winter wheat genotypes to FHB when exposed to the combined effects of cultivation practices, cultivar properties, year and the presence of interacting Fusarium spp. as an inherent whole. Analysed data originated from 633 grain samples collected from 434 localities in an eight-year period as a part of investigations related to the development of the DONcast® Europe prediction model. This study suggests that ploughing could increase the risk of the occurrence of less frequent toxigenic Fusarium species. Stubble management generated more divergent environmental factors than no-till farming, influencing greater variability in the relationship between deoxynivalenol (DON) accumulation and grain infection. The results of this study indicated differences in susceptibility reactions of varieties to FHB and suggested that more attention should be focused on the specificity of the interaction between variety and combined environmental stressors to ensure more predictive and sustainable wheat production.