The Infection of Yellow Lupin ( Lupinus luteus L.) with Bean Yellow Mosaic Virus (BYMV) and Cucumber Mosaic Virus (CMV) in Organic Farming in Eastern Poland

Yellow lupin seeds are a rich source of protein, which is why they are grown for animal feed and human consumption. At the same time, there is growing interest in organic farming. However, this type of cultivation is more susceptible to diseases, including viral ones. Yellow lupin is most commonly affected by the bean yellow mosaic virus (BYMV) and cucumber mosaic virus (CMV). We have therefore determined the occurrence of these two pathogens in six new Polish yellow lupin cultivars (Goldeneye, Salut, Diament, Puma, Mister and Bursztyn) grown in accordance with organic farming rules. Field experiments were conducted over three years, from 2022 to 2024, in three locations in eastern Poland. The Goldeneye cultivar was the most susceptible to BYMV, with an average infection rate of 59.17% of plants. In contrast, the Puma cultivar was the least susceptible to BYMV infection, with an average infection rate of 23.34%. However, even within this cultivar, most plants were infected under conditions of strong pathogen pressure (up to 90% in one of the locations in 2024). CMV infections were less frequent, with no statistical differences being found between cultivars in terms of the number of infected plants.