The influence of harvesting time and meteorological conditions on the occurrence of Fusarium species and mycotoxin contamination of spring cereals.

BACKGROUND: The aim was to determine the influence of harvesting time and meteorological conditions on the occurrence of Fusarium spp. and mycotoxins in the grain of spring cereals. A field experiment was performed in 2016-2018 with spring oat (Avena sativa L.) and spring triticale (× Triticosecale Wittm.) plots. Grain samples of oat and triticale were analysed for Fusarium infection and co-contamination with mycotoxins deoxynivalenol (DON), zearalenone (ZEA) and T-2 toxin (T-2). RESULTS: Results from the three-year study showed that the occurrence of Fusarium spp. fungi and mycotoxins produced by them in spring oat and triticale grain was most influenced by the meteorological conditions at harvesting time and crop species. CONCLUSIONS: It was found that in all experimental years, F. poae, F. tricinctum and F. sporotrichioides predominated in oat grains and F. graminearum, F. sporotrichioides and F. avenaceum predominated in spring triticale; as a result, oat grains were more contaminated with T-2 and triticale grains with DON and ZEA. Due to the rainy harvesting period in 2017, the contamination level of Fusarium fungi of grain of both crop species was 100%, and the concentrations of DON and ZEA in the samples of spring triticale were several times higher than those set forth in the EU regulation. Co-occurrence of all three mycotoxins analysed (DON, ZEA and T-2) was identified in these samples. © 2020 Society of Chemical Industry.

The Effect of Ustilago maydis and Delayed Harvesting on A- and B-Type Trichothecene Concentrations in Maize Grain.

The aim of this study was to investigate whether, in the context of a higher incidence of Ustilago maydis and Fusarium spp. at optimal and delayed harvest times, a higher incidence of mycotoxin contamination in maize grains could be expected. The field experiment was carried out at the Lithuanian Research Centre for Agriculture and Forestry experimental fields over three consecutive years (2020-2022). Two maize hybrids (Duxxbury and Lapriora) with different FAO numbers were used. The experimental design in the field was a randomized complete block design. Harvesting took place at three different times: first at physiological maturity, and then 10 (±2) and 20 (±2) days after the first harvest. Each hybrid had four repetitions at different harvest times. The U. maydis infection was only detected in 2021 and after the first harvest cobs were further divided into four different groups with four repetitions: healthy cobs, cobs visually infected with Fusarium spp., cobs visually infected with common smut, and cobs visually infected with both pathogens. No U. maydis-damaged maize cobs were found in 2020 and 2022. The levels of Fusarium microscopic fungi in maize grains were also from 4 to 16 times higher in 2021 than in 2020 and 2022. Harvest delays in 2020 led to a significant deoxynivalenol concentration increase in the Duxxbury hybrid and an HT-2 concentration increase in the Lapriora hybrid. In 2021, deoxynivalenol, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, and HT-2 concentrations significantly rose in both hybrids, but the T-2 concentration significantly increased only in the Lapriora hybrid. Deoxynivalenol concentrations were, respectively, 110 and 14.6 times higher than in cobs only infected with Fusarium spp. or U. maydis. Concentrations of 15-acetyl-deoxynivalenol were, respectively, 60, 67, and 43 times higher than in asymptomatic cobs and cobs only infected with Fusarium spp. or U. maydis. Cobs contaminated with both pathogens also had higher concentrations of 3-acetyl-deoxynivalenol. T-2 and HT-2 were detected in maize grains harvested from cobs infected only with Fusarium spp. The presence of U. maydis and Fusarium fungi in maize cobs, along with harvest delays, led to significant increases in mycotoxin concentrations, highlighting the importance of timely harvesting and pathogen management to mitigate mycotoxin contamination in maize grains.

T-2 and HT-2 toxins in harvested oat grains and their prevalence in whole grain flour during storage.

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.

The effect of technological processes on contamination with B-class trichothecenes and quality of spring wheat products from grain harvested at different times.

The study aimed to investigate the effect of technological processes on deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ADON) and 15-acetyl-deoxynivalenol (15-ADON) concentrations and quality of spring wheat products from grain harvested at different times. In this study, 408 samples were analysed for DON, 3-ADON and 15-ADON contamination by the HPLC method with UV detection. Delays in harvesting due to cool and rainy weather conditions resulted in increased DON, 3-ADON and 15-ADON levels. The highest DON concentrations were determined in bran. Higher DON concentrations in the bran indicate the protective function of the grain hull. On the other hand, the highest levels of minerals have been found in bran and whole grain flours, highlighting the importance of consuming these milling fractions as a mineral source with sustained health benefits. Our results showed that DON is stable at 170 °C, and high DON levels in whole-meal flour and white flour could not be converted or decomposed during baking. The levels of 3-ADON and 15-ADON in whole-meal flour bread and white flour bread were significantly reduced but not completely removed. The levels of DON and its derivatives 3-ADON and 15-ADON were significantly reduced in starch and gluten produced from contaminated whole meal flour; however, the washing process did not completely eliminate these toxic compounds. The concentrations of mycotoxins in starch and gluten remained relatively high. Negative correlation was found in highly contaminated samples between DON and bread baking properties. Also, inverse relationship was found between high mycotoxin concentrations and mineral element content in white flour.

Modelling the Effects of Weather Conditions on Cereal Grain Contamination with Deoxynivalenol in the Baltic Sea Region.

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.

The prevalence of deoxynivalenol and its derivatives in the spring wheat grain from different agricultural production systems in Lithuania.

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.