Alternaria are widespread fungi, saprophytes, and pathogens of agricultural plants which often colonize the seeds of cereal crops and are part of the complex of pathogens that causes black point. Their seeds and products are capable of synthesizing toxic metabolites, mycotoxins, which have an impact on the health of humans and animals.

This study was carried out at the Crop Research Institute in Prague, Czech Republic. Winter wheat seeds of the 2021-2022 harvest of the most common varieties were collected in different regions of the country. Mycological analysis of the seeds was carried out in the laboratory of Genetics and breeding methods of the Crop Research Institute. The identification of fungi of the genus Alternaria was carried out based on the morphological and cultural characteristics of colonies on PCA, the size and structure of conidia, and sporulation habits.

As a result of this study, the distribution of fungi of the genus Alternaria in winter wheat seeds affected by black point was studied. It was found that the frequency of occurrence of fungi of the genus Alternaria in the mycoflora of affected winter wheat grain in the Czech Republic in 2021 was 64,6%, and in 2022, it was 74,3% on average. The most frequently identified species were those belonging to the section Alternata, including Alternaria arborescens, Alternaria alternata, and Alternaria tenuissima. Their share in the population was 85,8% in 2021 and 96,5% in 2022. The species A. arborescens occupied a dominant position (47-49%) among fungi of this genus in the Alternaria population in the Czech Republic.

The Alternaria population in wheat seeds in the Czech Republic is dominated by fungi belonging to the section Alternata, which are capable of toxin formation. Regular monitoring of species diversity is necessary given its potential harmfulness when using wheat seed products.