Fusarium head blight (FHB) is one of the most serious diseases of small-grain cereals worldwide, resulting in yield reduction and an accumulation of the mycotoxin deoxynivalenol (DON) in grain. Weather conditions are known to have a significant effect on the ability of fusaria to infect cereals and produce toxins. In the past 10 years, severe outbreaks of FHB, and grain DON contamination exceeding the EU health safety limits, have occurred in countries in the Baltic Sea region. In this study, extensive data from field trials in Sweden, Poland and Lithuania were analysed to identify the most crucial weather variables for the ability of Fusarium to produce DON. Models were developed for the prediction of DON contamination levels in harvested grain exceeding 200 µg kg⁻¹ for oats, spring barley and spring wheat in Sweden and winter wheat in Poland, and 1250 µg kg⁻¹ for spring wheat in Lithuania. These models were able to predict high DON levels with an accuracy of 70–81%. Relative humidity (RH) and precipitation (PREC) were identified as the weather factors with the greatest influence on DON accumulation in grain, with high RH and PREC around flowering and later in grain development and ripening correlated with high DON levels. High temperatures during grain development and senescence reduced the risk of DON accumulation. The performance of the models, based only on weather variables, was relatively accurate. In future studies, it might be of interest to determine whether inclusion of variables such as pre-crop, agronomic factors and crop resistance to FHB could further improve the performance of the models.

In this work, we studied the impact of harvesting time on Fusarium mycotoxin occurrence in spring wheat and the effect of mycotoxin contamination on the quality of these grains. The spring wheat grains (Triticum aestivum L.) were collected in 2016–2018 when the crop had reached full maturity, 10 ± 2 days and 17 ± 3 days after full maturity. The grain samples were analyzed for Fusarium infection and co-contamination with mycotoxins deoxynivalenol (DON), zearalenone (ZEA), and T-2 toxin (T-2), as well as the quality of the wheat grains (mass per hectolitre, contents of protein, starch, ash and fat, particle size index (PSI), falling number, sedimentation, wet gluten content, and gluten index). The occurrence of Fusarium spp. fungi and the mycotoxins produced by them in the grains was mostly influenced by the harvesting time and meteorological conditions. The correlations between Fusarium species and the mycotoxins produced by them in the grains of spring wheat showed F. graminearum to be a dominant species, and as a result, higher concentrations of DON and ZEA were determined. The co-occurrence of all the three mycotoxins analyzed (deoxynivalenol, zearalenone, and T-2 toxin) was identified in wheat. In rainy years, a delay in harvesting resulted in diminished grain quality of spring wheat, as indicated by grain mass per hectolitre and falling number. Negative correlations were found in highly contaminated grains between mycotoxins (DON, ZEA, and T-2) and falling number and grain mass per hectolitre values.

Deoxynivalenol (DON) together with two acetylated derivatives, 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) occurs in cereal grains and their products. Co-occurrence of DON and acetylated derivatives in cereal grain is detected worldwide. Until now, DON and its derivatives have been considered equally toxic by health authorities. In this study, we analysed 103 samples of spring wheat grain, originating from the fields of different production systems in Lithuania, for the co-occurrence of type-B trichothecenes (DON, 3-ADON, 15-ADON). The samples were classified according to the production system—organic, sustainable and intensive. Mycotoxin levels in the spring wheat grain samples were determined by the HPLC method with UV detection. The type-B trichothecenes were found to be present at higher concentrations in the grain from the intensive production system. Eighty-one percent of the spring wheat grain samples from the intensive production system were co-contaminated with a combination of DON+3-ADON+15-ADON, 1% with DON+3-ADON. Additionally, DON+15-ADON and DON were found in 5% and 10% of the tested samples, respectively. Two percent of the samples were free from mycotoxins. In the grain samples from the sustainable production system, DON and a combination of DON+3-ADON showed a higher incidence – 47% and 23%, respectively. The samples with a combination of DON+3-ADON+15-ADON accounted for 18%. Completely different results were obtained from the analyses of organic grain samples. A large number of the organic spring wheat grain samples were contaminated with DON+3-ADON (55%) or DON (36%). The combination of DON+3-ADON+15-ADON was not present, while DON+15-ADON was present in 9% of the samples tested. The production systems did not lead to significant differences in mycotoxin levels, although a trend toward higher incidence and higher contamination was observed for the samples from the intensive and sustainable production systems.

Mycotoxin contamination of food is a constant global concern. There has been a scientific debate in Europe on the validation of accredited detection methods for type A trichothecenes T-2 and HT-2 and the restriction on dangerous concentrations. The issue is of great importance as this type of mycotoxin is frequently found in spring cereals grown in Lithuania. The aim of this study was to optimise and validate a method for the determination of T-2/HT-2 toxin concentrations in oats harvested in 2015–2018 and to observe the changes in the concentrations of both toxins in oat flour during 3- and 6-week storage at different temperatures and increased relative air humidity. All of the oat grain samples (100%) collected in 2015–2018 tested positive for contamination with type A trichothecenes. The highest mean co-contamination by T-2 + HT-2 (260.4 ± 140.9 µg/kg) and the highest concentration (594.6 µg/kg) were determined in 2018 when warm and wet weather conditions prevailed during oat flowering. The effect of long-term storage (6 weeks) on T-2 and HT-2 toxin production manifested itself only when the samples had been stored under cooler conditions (8 °C). The most important factors which impacted the variation of the concentrations of type A trichothecenes in flour were ambient temperature and storage time.