Wheat is the most widely grown field crop, which covers about 41.4% of arable land in Latvia. Tan spot, caused by Pyrenophora tritici-repentis, is the most widespread and devastating disease of wheat. The severity of tan spot is influenced by crop rotation, soil tillage, meteorological conditions, and biological traits of the pathogen.

The aim of this investigation was to analyse the severity of tan spot depending on agronomic practice, varieties, and meteorological conditions, and to characterise the diversity of the local population of Pyrenophora tritici-repentis.