Alternaria mycotoxins in wheat - A 10 years survey in the Northeast of Germany

•The most frequently found Alternaria mycotoxin in wheat was tenuazonic acid.•Alternariol was analysed only in 86 out of 1064 wheat samples.•A co-occurrence of several Alternaria mycotoxins in wheat samples was infrequent.•Maize and winter wheat as preceding crops led to increased TeA concentrations.

Although, the genus Alternaria is considered to be an important plant pathogen and capable to produce mycotoxins, the presence of Alternaria mycotoxins in cereals has been largely ignored both in Europe and overseas. This is very likely due to a lack of survey data. This study aimed at filling this gap by investigating a total of 1064 freshly harvested winter wheat samples from commercial farms in different regions of the State of Brandenburg (Germany) in the years from 2001 to 2010. We analysed alternariol (AOH), its monomethyl ether (AME), altenuene (ALT, since 2006) and tenuazonic acid (TeA) by a HPLC method with diode array and fluorescence detection. The most frequently found A. mycotoxin was TeA. An amount of 322 out of 1064 samples (30.3%) were naturally contaminated by TeA, 86 out of 1064 by AOH (8.1%), 33 out of 1064 by AME (3.1%) and 7 out of 267 samples (2.6%) were contaminated by ALT. The maximum toxin contents in all years were 4224 μg TeA kg−1, 832 μg AOH kg−1, 905 μg AME kg−1 and 197 μg ALT kg−1. A co-occurrence of several A. mycotoxins in wheat samples was infrequent: only three samples were contaminated by all the four toxins, 14 by three toxins, 61 by two toxins and 273 samples by only one toxin. The contamination of wheat ears in the State of Brandenburg in the wet years 2010, 2009 and 2002 were most pronounced, whereas 2001 and 2008 were A. “toxin free” years. The accumulation of TeA in freshly harvested wheat kernels seems to depend on preceding crop and tillage. Minimum tillage practices and maize as well as winter wheat as preceding crops led to increased TeA concentrations in wheat. A co-occurrence of mycotoxins produced by several mycotoxigenic fungi, e.g. Fusarium and Alternaria spp., is discussed.