DON content in oat grains in Norway related to weather conditions at different growth stages

High concentrations of the mycotoxin deoxynivalenol (DON), produced by Fusarium graminearum have occurred frequently in Norwegian oats recently. Early prediction of DON levels is important for farmers, authorities and the Cereal Industry. In this study, the main weather factors influencing myco-toxin accumulation were identified and two models to predict the risk of DON in oat grains in Norway were developed: (1) as a warning system for farmers to decide if and when to treat with fungicide, and (2) for authorities and industry to use at harvest to identify potential food safety problems. Oat grain samples from farmers’ fields were collected together with weather data (2004–2013) A mathematical model was developed and used to esti- mate phenology windows of growth stages in oats (til- lering, flowering etc.). Weather summarisations were then calculated within these windows, and the Spearman rank correlation factor calculated between DON- contamination in oats at harvest and the weather summarisations for each phenological window. DON contamination was most clearly associated with the weather conditions around flowering and close to har- vest. Warm, rainy and humid weather during and around flowering increased the risk of DON accumulation in oats, as did dry periods during germination/seedling growth and tillering. Prior to harvest, warm and humid weather conditions followed by cool and dry conditions were associated with a decreased risk of DON accumu- lation. A prediction model, including only pre-flowering weather conditions, adequately forecasted risk of DON contamination in oat, and can aid in decisions about fungicide treatments

Reduced risk of oat grain contamination with fusarium langsethiae and HT-2 and T-2 toxins with increasing tillage intensity

Frequent occurrences of high levels of Fusarium mycotoxins have been recorded in Norwegian oat grain. To elucidate the influence of tillage operations on the development of Fusarium and mycotoxins in oat grain, we conducted tillage trials with continuous oats at two locations in southeast Norway. We have previously presented the content of Fusarium DNA detected in straw residues and air samples from these fields. Grain harvested from ploughed plots had lower levels of Fusarium langsethiae DNA and HT-2 and T-2 toxins (HT2 + T2) compared to grain from harrowed plots. Our results indicate that the risk of F. langsethiae and HT2 + T2 contamination of oats is reduced with increasing tillage intensity. No distinct influence of tillage on the DNA concentration of Fusarium graminearum and Fusarium avenaceum in the harvested grain was observed. In contrast to F. graminearum and F. avenaceum, only limited contents of F. langsethiae DNA were observed in straw residues and air samples. Still, considerable concentrations of F. langsethiae DNA and HT2 + T2 were recorded in oat grain harvested from these fields. We speculate that the life cycle of F. langsethiae differs from those of F. graminearum and F. avenaceum with regard to survival, inoculum production and dispersal

Mycotoxins in organically versus conventionally produced cereal grains and some other crops in temperate regions

This paper presents peer-reviewed studies comparing the content of deoxynivalenol (DON), HT-2+T-2 toxins, zearalenone (ZEA), nivalenol (NIV), ochratoxin A (OTA) and fumonisins in cereal grains, and patulin (PAT) in apple and apple-based products, produced in organically and conventionally grown crops in temperate regions. Some of the studies are based on data from controlled field trials, however, most are farm surveys and some are food basket surveys. Almost half of the studies focused on DON in cereals. The majority of these studies found no significant difference in DON content in grain from the two farming systems, but several studies showed lower DON content in organically than in conventionally produced cereals. A number of the investigations reported low DON levels in grain, far below the EU limits for food. Many authors suggested that weather conditions, years, locations, tillage practice and crop rotation are more important for the development of DON than the type of farming. Organically produced oats contained mainly lower levels of HT-2+T-2 toxins than conventionally produced oats. Most studies on ZEA reported no differences between farming systems, or lower concentrations in organically produced grain. For the other mycotoxins in cereals, mainly low levels and no differences between the two farming systems were reported. Some studies showed higher PAT contamination in organically than in conventionally produced apple and apple products. The difference may be due to more efficient disease control in conventional orchards. It cannot be concluded that any of the two farming systems increases the risk of mycotoxin contamination. Despite no use of fungicides, an organic system appears generally able to maintain mycotoxin contamination at low levels. More systematic comparisons from scientifically controlled field trials and surveys are needed to clarify if there are differences in the risk of mycotoxin contamination between organically and conventionally produced crops. </jats:p

Evaluation of rapid test kits for quantification of HT-2 and T-2 toxins in naturally contaminated oats

The aim of this study was to evaluate the performance and usefulness of three rapid test kits for analysis of HT-2 and T-2 toxins (HT-2 and T-2), two of the most potent trichothecenes commonly found in European oats. Concentrations of these two toxins combined (HT-2+T-2) were analysed in naturally contaminated oat samples (n=68) using the following test kits: Ridascreen® FAST T-2 Toxin (‘Fast ELISA’), DRAFT Ridascreen® HT-2/T-2 (‘Standard ELISA’, not commercially available), and the lateral flow device ROSA® HT-2-T-2 (‘Rosa LFD’). Mycotoxin analysis by LC-MS/MS was used as a reference method. Rosa LFD offered the best reliability, achieving detection that was stable across toxin levels, whereas detection by both ELISA kits differed significantly among toxin levels (P&lt;0.01). The kits were also evaluated regarding agreement with the reference method (measured as Cohen's kappa) at a HT-2+T-2 concentration of 1000 μg/kg in naturally contaminated oats. Agreement was greatest for Rosa LFD (89.2%), intermediate for Standard ELISA (66.8%), and lowest for Fast ELISA (62.2%). Rosa LFD showed cross-reaction of 100% with both T-2 and HT-2. For the ELISA kits, cross-reactions were 100% with T-2 but below 100% with HT-2. Therefore, to estimate the sum of HT-2 and T-2 in an oat sample, it was necessary to re-calculate the data from both ELISA kits according to the known cross-reaction of each kit with HT-2 and the concentration ratio of HT-2 to T-2 in Norwegian oats. Rosa LFD had the highest correlation with LC-MS/MS (R2=0.94), and the corresponding R2 values for Fast and Standard ELISA were 0.61 and 0.83, respectively. Rosa LFD was well suited for on-site detection. Standard ELISA allows simultaneous testing of several samples that are useful for centralised laboratories. </jats:p

Evaluation of rapid test kits for quantification of deoxynivalenol in naturally contaminated oats and wheat

The aim of this study was to evaluate the performance of rapid test kits for analysis of deoxynivalenol (DON), a mycotoxin commonly found in small-grain cereals. Concentrations of DON and its acetylated derivative 3-acetyldeoxynivalenol (3-ADON) were analysed in naturally contaminated wheat (n=56) and oats (n=81) using two enzyme-linked immunosorbent assays, i.e. Ridascreen® DON (‘Standard ELISA’) and Ridascreen® FAST DON (‘Fast ELISA’), and two lateral flow devices, i.e. Rida® QUICK DON (‘Quick LFD’) and Rosa® DON (‘Rosa LFD’). Analysis by the LC-MS/MS reference method showed a median DON + 3-ADON concentration of 1,168 μg/kg (90th percentile 3,264 μg/kg) in wheat and 2,250 μg/kg (90th percentile of 9,008 μg/kg) in oats. Rosa LFD offered the best reliability, achieving detection that was stable across toxin levels in both matrices. In addition, Rosa LFD had the highest accuracy (i.e. proportion of correct results) at a DON level of 1,250 μg/kg in wheat (0.83) and 8,000 μg/kg in oats (0.96). Standard ELISA achieved the highest accuracy at a DON level of 1,750 μg/kg in oats (0.85). Detection by Quick LFD in wheat and Fast ELISA in both wheat and oats differed significantly among toxin levels (P≤0.05), with recoveries outside European Union requirements (70-120%) in some cases. The correlation with results from LC-MS/MS analysis in oats was best for Rosa LFD (R2=0.79). In wheat, however the correlation was best for Fast ELISA (R2=0.81). Rosa LFD was regarded as well-suited for on-site detection. Standard ELISA allowed simultaneous testing of several samples and achieved detection that was stable across toxin levels in both matrices, making it a useful alternative in laboratories. To our knowledge, this is the first report describing the performance of rapid test kits for detection of DON in naturally contaminated oats. </jats:p

Different resistance to DON versus HT2 + T2 producers in Nordic oat varieties

Over recent decades, the Norwegian cereal industry has had major practical and financial challenges associated with the occurrence of Fusarium head blight (FHB) pathogens and their associated mycotoxins in cereal grains. Deoxynivalenol (DON) is one of the most common Fusarium-mycotoxins in Norwegian oats, however T-2 toxin (T2) and HT-2 toxin (HT2) are also commonly detected. The aim of our study was to rank Nordic spring oat varieties and breeding lines by content of the most commonly occurring Fusarium mycotoxins (DON and HT2 + T2) as well as by the DNA content of their respective producers. We analyzed the content of mycotoxins and DNA of seven fungal species belonging to the FHB disease complex in grains of Nordic oat varieties and breeding lines harvested from oat field trials located in the main cereal cultivating district in South-East Norway in the years 2011–2020. Oat grains harvested from varieties with a high FHB resistance contained on average half the levels of mycotoxins compared with the most susceptible varieties, which implies that choice of variety may indeed impact on mycotoxin risk. The ranking of oat varieties according to HT2 + T2 levels corresponded with the ranking according to the DNA levels of Fusarium langsethiae, but differed from the ranking according to DON and Fusarium graminearum DNA. Separate tests are therefore necessary to determine the resistance towards HT2 + T2 and DON producers in oats. This creates practical challenges for the screening of FHB resistance in oats as today’s screening focuses on resistance to F. graminearum and DON. We identified oat varieties with generally low levels of both mycotoxins and FHB pathogens which should be preferred to mitigate mycotoxin risk in Norwegian oat

Weather patterns associated with DON levels in Norwegian Spring Oat grain: a functional data approach

Fusarium graminearum is regarded as the main deoxynivalenol (DON) producer in Norwegian oats, and high levels of DON are occasionally recorded in oat grains. Weather conditions in the period around flowering are reported to have a high impact on the development of Fusarium head blight (FHB) and DON in cereal grains. Thus, it would be advantageous if the risk of DON contamination of oat grains could be predicted based on weather data. We conducted a functional data analysis of weather-based time series data linked to DON content in order to identify weather patterns associated with increased DON levels. Since flowering date was not recorded in our dataset, a mathematical model was developed to predict phenological growth stages in Norwegian spring oats. Through functional data analysis, weather patterns associated with DON content in the harvested grain were revealed mainly from about three weeks pre-flowering onwards. Oat fields with elevated DON levels generally had warmer weather around sowing, and lower temperatures and higher relative humidity or rain prior to flowering onwards, compared to fields with low DON levels. Our results are in line with results from similar studies presented for FHB epidemics in wheat. Functional data analysis was found to be a useful tool to reveal weather patterns of importance for DON development in oats