Crown rust is a world-wide disease on wild and on cultivated species of oat.
In Morocco, this disease is considered as a major cause of yield reduction, which must be controlled by genetic resistance of the host. The analysis of the rust isolates collected in these regions revealed a large number of biotypes, which do not differ meaningfully by their virulence whatever the region. Six genotypes belonging to the species Avena maroccana and one genotype belonging to the species Avena sterilis were selected for their resistance in the field and were analysed in controlled conditions of inoculation by four isolates carrying a large number of virulence genes.