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Resistance of 35 winter wheat varieties to the accumulation of mycotoxins deoxynivalenol (DON) and zearalenone (ZEA) in grain was evaluated in field trials lasting three years (2004, 2005, 2006) after artificial inoculation with <i>Fusarium culmorum</i>. Data on DON and ZEA content were supplemented by symptom scores and determination of % of Fusarium damaged grains and % reductions of thousand grain weight and grain weight per spike due to infection. The conditions of experimental years highly influenced the performance of all characters. The highest production of DON occurred in 2006 at a high temperature and high moisture content during the infection period. Moderate resistance to the accumulation of DON (at the level of Swiss variety Arina) was detected in the varieties Apache, Samanta, Simila and Alana. Another six varieties (Rheia, Banquet, Ludwig, Rapsodia, Dromos and Globus) also showed relatively low average DON content, but a higher fluctuation in experimental years. DON content was positively related to ZEA content and significant correlations were also detected between DON content and the examined disease severity traits. In all years the earlier varieties showed lower DON accumulation than later varieties, but the effects of genotype earliness on the other traits, including ZEA content, were not often significant (not similar under different conditions). The obtained results could help to improve the classification of varieties from these aspects, which is desirable for recommendation on their use in practice and breeding.

Progression of deoxynivalenol (DON) concentrations in spikes and kernels was studied in relation to Fusarium head blight (FHB) symptoms in five winter wheat cultivars, differing in resistance to FHB, after single floret inoculation with an aggressive isolate of Fusarium culmorum. After inoculation in field conditions the spikes were detached from the plant and kept in the greenhouse under controlled conditions. High concentrations of DON were detected in susceptible cultivars at an early stage of pathogenesis (7 days after inoculation). Over the whole examined 21-day period and also at maturity spikes contained more DON than kernels. While differences between cultivars in the accumulation of DON were highly expressed already 7 days after inoculation, differences in symptomatic reactions were not clear until day 21. Owing to the reported crucial role of DON at early stages of pathogenesis, the importance of appropriate timing of fungicide application is highly stressed.

A survey of deoxynivalenol (DON) content in cereals intended for human consumption was carried out in the Czech Republic (CR) over a seven-year period (2000-2006). Wheat, barley and rye samples of harvested cereals were collected directly from farmers where the selection was based on sample origin. In wheat, randomly sampled spikes and risk samples selected on the basis of visually scabby kernels (VSK) were also analysed. An immunochemical method, ELISA, was used for analysis. The maximum limit, according to Commission Regulation (EC) No. 1881/2006, for DON content (1,250 µg/kg) in unprocessed cereals for human nutrition was exceeded in random samples of wheat in 3.5% out of 345 analysed samples, of barley in 1.6% out of 498 analysed samples, and there were no samples of rye (out of 113) exceeding this limit. The analysis of spike samples and the samples that were selected based on VSK occurrence revealed much higher levels of DON content. Highly significant effects of the year, sample origin, and preceding crop on the DON content were found.

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