The Effect of Fungicide Protection on Mycotoxin Contamination and Microscopic Fungi in Spring Barley Grain Cultivated in Northeastern Poland

A three-year experiment was conducted over the years 2020–2022 to determine the spectrum of microscopic fungi colonizing the grain of two fungicide-treated cultivars of spring barley and the profiles of mycotoxins identified in grain. In comparison with the unprotected control, fungicide treatment significantly increased grain yield by an average of approximately 10% in cv. Atrika and approximately 20% in cv. Vermont. The most abundantly isolated species were Alternaria alternata and Bipolaris sorokiniana. Fungi of the genus Fusarium were also widely represented, accounting for 7% to 27% of all isolates, depending on the year. Each year, 45 secondary fungal metabolites produced mainly by Fusarium and Alternaria species were identified. Fungicide protection did not reduce the overall concentration of Fusarium toxins and even caused a slight increase, while contributing to a decrease in the levels of nivalenol-3-glucoside, nivalenol, and deoxynivalenol. Concurrently, the concentrations of group A trichothecenes and moniliformin increased. The grain of spring barley cv. Vermont contained higher levels of the major Fusarium toxins than the grain of cv. Atrika. Non-parametric Friedman ANOVA revealed significant differences between years for eight mycotoxin concentrations. These results confirm the complex effects of chemical protection on the composition of grain microflora and mycotoxin profiles, indicating the need for further research into interactions between cultivars, environmental conditions, and integrated plant protection strategies in the production of food and feed cereals to improve food safety.