Winter wheat grain yield response to fungicide application at different stages and fusarium head blight is rather influenced by variety and year

Winter wheat is susceptible to several diseases throughout the vegetative season whereas fungicide treatments are protection used to combat fungal pathogens and to improve plant growth thus mitigating grain yield reductions. One of the main diseases is Fusarium head blight (FHB) which can be a huge problem in wheat production. Twelve winter wheat varieties varying in FHB sensitivity were tested for control of FHB using fungicide treatments made in tillering or/and heading stage, with or without inoculation with Fusarium spp. to determine the grain yield response to fungicide application at different growth stages. The grain yield from fungicide treated plots was compared to non-treated plots in two seeding rates and Fusarium inoculated plots in two growing seasons (2019/2020 and 2020/2021). The average area under the disease progress curve (AUDPC) for Type I resistance was 109.48 in 2020 and 99.33 in 2021 year in VI treatment where fungicide application in heading and Fusarium inoculation simultaneously were performed. In VII treatment where only Fusarium inoculation was applied, AUDPC for Type I resistance in 2020 was 371.88 in average, while in 2021 that was 199.18 in average. Wheat varieties treated with a fungicide in the heading stage at the first year of investigation (2020) had higher grain yield, compared to non-treated plots or treated in tillering stage. These results indicated that application of fungicides in heading stage when there is sufficient moisture in May and June may increase chances of profitability from fungicide application at that growth stage. Cumulative rainfall from January till May, at year 2021 had a positive effect on the grain yield, when accumulated rainfall in this period increased chances of getting a higher yield response from fungicide application in the tillering stage. Fungicide applications should always be implemented in combination with sound agronomic management and FHB resistant varieties.