Nordic-Baltic Fusarium seminar-Challenges and recent updates

Time: 18-19 November, 2014
Place: Helsinki, Finland

This seminar was the third Nordic Baltic Fusarium seminar arranged by the NJF working group on Fusarium and mycotoxins. Three main topics were chosen: 1) Plant-Fusarium interactions; 2) Toxicity, masked mycotoxins and synergism; and 3) Management of Fusarium and mycotoxins. The invited guest speakers on these topics were: 1) Paul Nicholson from John Innes Institute, UK; 2) Isabelle Oswald from INRA Toulouse, France; and 3) Simon Edwards from Harper-Adams University, UK.

In the first session, Paul Nicholson gave a wide view of resistance to Fusarium head blight (FHB) in wheat and barley, types of resistance and their assessment. His conclusion was that the focus in reducing FHB in wheat should be on elimination of susceptibility instead of resistance. Morten Lillemo from NMBU, Norway, continued the resistance theme with results from practical breeding trials on oats, two-row barley and wheat. Cultivars with high and low deoxynivalenol (DON) have been identified in oats, barley and wheat. Flowering biology seems to be important for head blight in all cereals. Arja Laitila from VTT, Finland, presented results of transcriptional profiling applied to study Fusarium gene expression in barley during crop development. The onset of Fusarium activity could be indicated. The biosynthesis of T-2/HT-2 toxins can start at an early growth phase of the fungus and toxins can be detected in plants already at ear emergence. Erik Lysoe from Bioforsk, Norway, presented results of Fusarium avenaceum and the metabolites this very common species can produce. Paula Persson from SLU, Sweden, discussed Fusarium graminearum, its spread and symptoms in field conditions and infections spreading to new areas with cereal seed. Skaidre Suproniene from Lithuania presented results on DON derivatives in Lithuanian cereal grain, where 15-ADON is more prevalent than 3-ADON.

In the second session, Isabelle Oswald described toxic effects induced by DON, A-DONs and DON glucosinolates. DON can affect the immune system, food consumption and growth of animals and cause acute illness in humans. In studies, DON-3-glucosinolate has been proven to be non- toxic and 3-ADON less toxic than DON, while 15-ADON is more toxic than DON. These results show that DON derivatives should be taken into account in cereal risk assessment. Masked mycotoxins are metabolites of toxins which cannot be detected in regular toxin analyses. Alexis Nathanail from Evira, Finland, presented results of development of an analytical method for simultaneous detection of DON, NIV, ZEN, T-2 and HT-2 and some of their metabolites in wheat, barley and oat flours. Jens Laurids Sørensen from Aalborg University, Denmark, reported results on secondary metabolites of F. graminearum produced during infection and potential contamination in food and feed. Chris Miles from Norway described possibilities for detoxification of DON in grain products by using thiols to produce conjugates. Gunnar Eriksen from Norway made an overview of mycotoxin effects and TDI values for humans at different ages. The conclusion was that 1- to 2-year-old children may exceed the TDI for T-2/HT-2 in their food. Exposure to toxins can take place also by inhalation and workers on grain elevators and mills can be exposed to several mycotoxins in grain dust. Anita Solhaug, Norway, described potential immune effects of alternariol, ENNs, ZEN, DON and sterigmatocystin and concluded that these compounds have cytotoxic effects and may have immunological responses.

In the third session, Simon Edwards described the DON situation in the UK: the contamination levels in UK oats are relatively low compared with those in wheat. On the other hand, T-2/HT-2 contamination levels in oats are relatively high, with on average 16% of samples analysed annually exceeding the 1000 ppb limit. Good Agricultural Practice for reducing mycotoxins includes less cereal-intense rotations and cultivation of spring oats instead of winter cultivars. Fungicide use does not reduce T-2/HT-2 contamination. Organic production, although detected mycotoxin levels are lower, is not a better option in production than less cereal-intense rotations. Guro Brodal from Bioforsk, Norway, described the effects of storage in reducing Fusarium infection in grain and increasing germination. Storage for five months could increase germination in barley and oats to meet certification requirements, but in wheat this was not observed. Selamawit Tekle from NMBU, Norway, indicated that according to their results, visible and near infrared (VIS-NIR) reflectance spectroscopy can be used in Fusarium-inoculated nurseries to discard the least resistant genotypes. Hyperspectral imaging can be applied to detect DON and Fusarium on whole kernels to detect and remove Fusarium-damaged kernels and reduce DON contamination. Ingerd Hofgaard and Anne-Grete Hjelkrem fom Bioforsk, Norway, reported on the effects of agricultural practices and weather on mycotoxin contamination. Tillage practices, straw management, crop rotation and different chemical and biological control treatments have been studied. DON producer F. graminearum is common on straw, but T-2 producer F. langsethiae is seldom detected in crop residues. Accumulation of DON was generally best correlated with weather around flowering and prior to harvest, but such correlations were not found between T-2/HT-2 and weather. High DON contaminations were detected in south-southwest Sweden in 2012-2014. According to Thomas Börjesson from Lantmännen, Sweden, the preliminary results indicate that models based on precipitation in April and from early July to close to maturity, and wind direction in spring, fairly well predicted observed mycotoxins. Ruth Dill-Macky, from the University of Minnesota, USA, described the national forecasting system developed there and how best management practices are recommended for growers who also know the best possibilities for chemical FHB control. However, high DON contaminations are occasionally detected, possibly due to uneven crop development caused by cool conditions.

In addition to invited lectures, the sessions contained 16 oral presentations. There were also 17 presentations in the poster session, which was arranged as short, four-minute talks by the posters. The topics were: Occurrence of Fusarium and mycotoxins (7 posters), Control of Fusarium and mycotoxins (4 posters), Toxicity (3 posters) and Fusarium biology (3 posters). The seminar had 78 participants from 13 countries (Finland 30, Sweden 15, Norway 14, Denmark 4, Estonia 3, Latvia 3, Lithuania 1, Russia 2, UK 2, France 1, USA 1, Australia 1 and Austria 1).

The next Nordic Baltic Fusarium seminar will be arranged in Latvia in March 2017.