The occurrence of deoxynivalenol in Norwegian cereals—differences between years and districts, 1988–1996

Abstract

The amount of the Fusarium toxin deoxynivalenol (DON) has been determined in about 5000 samples of barley, oats and wheat grown in Norway. The samples were collected from 1988 through 1996. Of all samples analysed, 68.9% contained DON concentrations exceeding 30 μg/kg; 61.3% of the barley, 81.4% of the oats, and 61.5% of the wheat samples. The percentages of barley, oats and wheat samples containing 1,000 μg DON per kg or more were 6.6, 12.5 and 3.1, respectively. Oats produced in commercial fields were found to be significantly more contaminated with DON than barley and wheat. A strong positive correlation (r = 0.86) was found between the mean DON content and the amount of precipitation in July. Grains exposed to wet weather in the period after mealy ripe were, in some cases, heavily contaminated with DON, even with temperatures down to 0°C. The contamination level varied significantly from district to district, even in neighbouring districts, being lowest in the main grain‐growing regions in Norway. In Tr⊘ndelag, the most northern grain‐growing area in Norway, oats generally were more exposed to DON contamination than oats from the rest of the country, while the opposite seemed to be the case for barley.