Differential response of pea (Pisum sativum) to rusts incited by Uromyces viciae-fabae and U. pisi

Pea rust is reported to be incited by both Uromyces viciae-fabae and U. pisi. However we found that in Córdoba (Spain), pea was more severely infected by U. pisi. We observed that although pea seedlings were slightly susceptible to U. viciae-fabae infection under controlled conditions, pea accessions were little damaged by this pathogen under field conditions, due to high levels of pre-haustorial resistance. The observations with Spanish isolates were confirmed with isolates of U. viciae-fabae from the Netherlands, Syria and Australia. In general, pea accessions displayed a compatible reaction against all the isolates of U. viciae-fabae studied, but levels of infection were very low on peas, markedly reduced compared to the faba bean check. For these reasons, we consider the pathogen U. pisi as the principal agent causing pea rust. However, we cannot discard the possibility of specialization within U. viciae-fabae on pea, as specialization on vetch and lentil has already been documented.