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Over an eight-year period, 686 winter wheat grain samples and information on their cropping history were obtained from Swiss growers. To estimate the risk of Fusarium head blight (FHB), grains were examined for Fusarium species incidence, mycotoxin content as well as the abundance of F. graminearum (FG) and F. poae (FP) DNA and three chemotypes, 15-acetyl-deoxynivalenol (15ADON), 3-acetyl-deoxynivalenol (3ADON) and nivalenol (NIV). Of all Fusarium species, FG and FP were predominant, and the average abundance of the FG DNA was three times higher compared with that of FP. The average detection of the 15ADON chemotype was twice as high as those of 3ADON and NIV, respectively. Deoxynivalenol (DON), zearalenone (ZEA) and nivalenol (NIV) were the most frequently detected toxins. For DON, 11% and for ZEA, 7% of all samples exceeded the European maximum limits for unprocessed cereals intended for human consumption. Furthermore, NIV was most likely produced by four different Fusarium species. A multiple correspondence analysis revealed that high levels of FG and DON were mainly observed in grain samples from fields with the previous crop maize, reduced tillage, cultivars with poor FHB resistance and strobilurin-based fungicides. Other previous crops and/or ploughing decreased the DON content by 78 to 95%. ZEA showed a similar pattern. In contrast, high levels of FP and NIV were associated with samples from ploughed fields and the previous crop canola. These findings and the negative correlations between FP DNA and FG incidence, ZEA and DON suggest a different ecological niche for FP or diverging requirements for growth and infection.

Fusarium head blight (FHB) is a devastating disease of wheat. Worldwide, Fusarium graminearum is the most dominant FHB-causing species. Its most common toxin, deoxynivalenol (DON), impairs food and feed safety and has an enormous economic impact. Agronomic factors such as crop rotation, soil management and host genotype strongly influence the occurrence of F. graminearum. Infected plant debris from previous crops, on which perithecia and ascospores develop, represent the main source for FHB, and hence, improved cropping systems aim to reduce this inoculum to decrease the infection risk. The best measure to evaluate the disease pressure is spore traps that detect deposited airborne ascospores. Commercial spore traps are expensive and require power sources, thus, they are not suitable for investigations in field experiments with different treatments. In consequence, we developed spore traps containing a Petri dish with Fusarium-selective agar, protected by aluminum dishes and attached on a wooden board. We compared the data of our low-cost trap with those of a commercial high-throughput jet sampler and obtained equivalent results. In field experiments to compare cropping systems, we observed a high correlation between the DON content in wheat grains and the number of colonies from deposited spores. Our spore trap proved to be a highly valuable tool to not only study FHB epidemiology but also to identify innovative cropping systems with a lower risk for FHB and DON contamination.

To assess the in vitro activity of three phenolic acids (ferulic acid, p-hydroxybenzoic acid, vanillic acid) and two flavonols (quercetin, rutin) on mycelial growth and mycotoxin accumulation of Fusarium graminearum (FG), F. langsethiae (FL) and F. poae (FP), two different approaches were chosen. First, grains from oat varieties were inoculated with a suspension of three FL isolates to determine the influence of phenolic compounds on the accumulation of mycotoxins. The oat variety Zorro showed a tendency for lower accumulation of T-2/HT-2, diacetoxyscirpenol and neosolaniol. Second, a mycelium growth assay was conducted to follow FG, FL and FP growth on cereal based media supplemented with phenolic compounds. Increasing concentrations of ferulic acid substantially inhibited growth of FG and FL, while FP growth was reduced to 57%. In contrast, p-hydroxybenzoic acid, vanillic acid, quercetin, and rutin slightly stimulated mycelium growth. Results about mycotoxin production in cereal based media were less conclusive.

Fusarium head blight is one of the most noxious cereal diseases. Worldwide, F. graminearum (FG) and the mycotoxin deoxynivalenol (DON) is the most dominant species/mycotoxin in barley and wheat. Barley is often produced as on farm feed and thus routine mycotoxin analyses similar to those of cereals for human consumption are not performed. Hence, an early prediction of mycotoxin levels is important for farmers to minimise the risk of contaminated feed but also of contaminated cereals entering the cereal supply chain. Therefore, climate chamber experiments with artificial FG infection of barley investigating the influence of different temperatures (10 °C, 15 °C, 20 °C) and durations (4 h, 8 h, 12 h) at 99% relative humidity were conducted to accumulate data to develop a forecasting system. An up to three times higher DON contamination in the 15 °C treatments for the feed barley variety Ascona was detected compared with the 10 °C and 20 °C treatments. For the malting barley variety Concerto, the prolonged humidity durations had a stronger effect under all tested temperatures and resulted in up to two times higher DON contaminations. In addition, field experiments where spore deposition during anthesis as well as disease incidence, fungal amount and mycotoxins were observed, showed that the overwintered straw treatment resulted, depending on the year, in a three times higher FG incidence and DON content compared with the control and freshly inoculated straw treatment.

Between 2013 and 2015, 325 samples of commercially grown oats were collected in Switzerland along with data on respective cropping factors. The incidence of different Fusarium species was determined using a seed health test and quantitative PCR was used to measure the amount of F. poae and F. langsethiae DNA. Mycotoxins were quantified by LC–MS/MS. Among all Fusarium species, F. poae was found to be dominant whereas T-2/HT-2 toxins were the major mycotoxins. Samples from fields with the previous crop cereal showed the highest concentrations of T-2/HT-2. Higher amounts of nivalenol (NIV) and T-2/HT-2 were detected in samples from fields with reduced tillage compared with samples from ploughed fields. Furthermore, we observed a higher contamination with NIV and T-2/HT-2 in winter sown varieties compared with spring sown varieties. Results from the current study are highly valuable to develop recommendations for optimised cropping systems that reduce the risk of mycotoxin contamination of oat grains.

Suspensions or solutions with 1% of Chinese galls (Galla chinensis, GC) or 1% of tannic acid (TA), inhibited germination of conidia or mycelium growth of Fusarium graminearum (FG) by 98%–100% or by 75%–80%, respectively, whereas dried bark from buckthorn (Frangula alnus, FA) showed no effect at this concentration. In climate chamber experiments where the wheat variety “Apogee” was artificially inoculated with FG and F. crookwellense (FCr) and treated with 5% suspensions of TA, GC and FA, the deoxynivalenol (DON) content in grains was reduced by 81%, 67% and 33%, respectively. In field experiments with two commercial wheat varieties and artificial or semi-natural inoculations, mean DON reductions of 66% (TA) and 58% (FA), respectively, were obtained. Antifungal toxicity can explain the high efficacies of TA and GC but not those of FA. The Fusarium head blight (FHB) and mycotoxin reducing effect of FA is probably due to elicitation of resistance in wheat plants. With semi-natural inoculation, a single FA application in the first half of the flowering period performed best. However, we assume that applications of FA at the end of ear emergence and a treatment, triggered by an infection period, with TA or GC during flowering, might perform better than synthetic fungicides.

Fusarium head blight is one of the most important cereal diseases worldwide. Cereals differ in terms of the main occurring Fusarium species and the infection is influenced by various factors, such as weather and cropping measures. Little is known about Fusarium species in barley in Switzerland, hence harvest samples from growers were collected in 2013 and 2014, along with information on respective cropping factors. The incidence of different Fusarium species was obtained by using a seed health test and mycotoxins were quantified by LC-MS/MS. With these techniques, the most dominant species, F. graminearum, and the most prominent mycotoxin, deoxynivalenol (DON), were identified. Between the three main Swiss cropping systems, Organic, Extenso and Proof of ecological performance, we observed differences with the lowest incidence and toxin accumulation in organically cultivated barley. Hence, we hypothesise that this finding was based on an array of growing techniques within a given cropping system. We observed that barley samples from fields with maize as previous crop had a substantially higher F. graminearum incidence and elevated DON accumulation compared with other previous crops. Furthermore, the use of reduced tillage led to a higher disease incidence and toxin content compared with samples from ploughed fields. Further factors increasing Fusarium infection were high nitrogen fertilisation as well as the application of fungicides and growth regulators. Results from the current study can be used to develop optimised cropping systems that reduce the risks of mycotoxin contamination.

To assess the occurrence of Fusarium toxins in wheat in Switzerland, an eight-year survey was conducted by analysing a total of 686 harvest samples from growers using LC-MS/MS. Between 2007 and 2010, 527 samples were obtained from 17 cantons. Between 2011 and 2014, 159 samples were collected from the canton Berne. The most frequent toxins detected were deoxynivalenol (DON), zearalenone (ZEA) and nivalenol (NIV). The overall mean DON content in all samples was 607 µg/kg, and 11% exceeded the European limit for unprocessed cereals for foodstuffs (1250 µg/kg). For ZEA (mean 39 µg/kg), 7% exceeded the respective limit (100 µg/kg), and the mean content of NIV (no limit established) was 15 µg/kg. Between the years, the ratio of mycotoxin-contaminated samples ranged between 52% and 98% for DON, 9% and 43% for ZEA and 0% and 49% for NIV. The yearly mean contents varied substantially between 68 and 1310 µg/kg for DON, 5 and 56 µg/kg for ZEA and 6 and 29 µg/kg for NIV. The geographic origin showed a significant effect on DON and ZEA contamination, but was inconsistent between the years. This study has shown that the majority of Swiss-produced wheat is, in terms of Fusarium toxins, fit for human consumption and feed purposes. Nevertheless, depending on the year, high toxin contents can be expected, an issue that growers, cereal collection centres and the food industry have to deal with to ensure food and feed safety.

To assess the occurrence of Fusarium toxins in wheat in Switzerland, an eight-year survey was conducted by analysing a total of 686 harvest samples from growers using LC-MS/MS. Between 2007 and 2010, 527 samples were obtained from 17 cantons. Between 2011 and 2014, 159 samples were collected from the canton Berne. The most frequent toxins detected were deoxynivalenol (DON), zearalenone (ZEA) and nivalenol (NIV). The overall mean DON content in all samples was 607 µg/kg, and 11% exceeded the European limit for unprocessed cereals for foodstuffs (1250 µg/kg). For ZEA (mean 39 µg/kg), 7% exceeded the respective limit (100 µg/kg), and the mean content of NIV (no limit established) was 15 µg/kg. Between the years, the ratio of mycotoxin-contaminated samples ranged between 52% and 98% for DON, 9% and 43% for ZEA and 0% and 49% for NIV. The yearly mean contents varied substantially between 68 and 1310 µg/kg for DON, 5 and 56 µg/kg for ZEA and 6 and 29 µg/kg for NIV. The geographic origin showed a significant effect on DON and ZEA contamination, but was inconsistent between the years. This study has shown that the majority of Swiss-produced wheat is, in terms of Fusarium toxins, fit for human consumption and feed purposes. Nevertheless, depending on the year, high toxin contents can be expected, an issue that growers, cereal collection centres and the food industry have to deal with to ensure food and feed safety.

Over the course of 5 years, different maize residue treatments were conducted on 14 zero tillage on-farm sites in Switzerland to evaluate their effect on the development of Fusarium head blight (FHB) and the contamination with the mycotoxin deoxynivalenol (DON) in winter wheat grains and wheat straw following grain maize. Two experimental series with three and five different treatments were carried out, respectively. Fusarium graminearum (Schwabe) was the predominant FHB-causing species with an overall incidence of 15% infected wheat grains. A significant correlation between symptoms in the field, F. graminearum incidence and DON content in wheat grains and wheat straw was observed. The average DON content in both wheat grains and wheat straw was approximately 5,000 μg/kg and thus several times higher than the European maximum limit of 1,250 μg/kg for unprocessed small-grain cereals for human consumption. Of all grain samples, 74% were above the maximum limit. Pooled over both experimental series, the average reduction of DON in grains through treatments of the maize residue compared with a control treatment ranged between 21 and 38%. The effect of various other factors, including the year, the wheat variety, the site, the maize hybrid and the production system was evaluated as well. The year and the wheat variety were the most important FHB influencing factors. Over all treatments, the variety Levis showed a fivefold higher average DON content compared with the variety Titlis. From different categories of maize residue particles, intact pieces of 5–15 cm length were strongly correlated with F. graminearum incidence and DON content in grains. During the time course of this study, the recommendation from a preliminary version of the internet-based DON forecasting system FusaProg to apply or to omit a fungicide treatment was correct in 32 out of 42 cases. The results are currently being used to optimise the FusaProg models. This study has shown that in a grain maize/winter wheat rotation, the DON content in wheat grains frequently exceeded the European maximum limit, even with a thorough treatment of maize residues and less susceptible wheat varieties. Hence, in order to reduce the contamination risk in a zero tillage system, the crop rotation needs to be modified.