Hosts of "Aphanomyces euteiches" can be annuals or perennials in the legume family, including: pea ("Pisum sativum"), alfalfa ("Medicago sativa"), snap bean and red kidney bean ("Phaseolus vulgaris"), faba bean ("Vicia faba"), red clover ("Trifolium pratense"), and white clover ("Trifolium repens"). Of particular concern is "Aphanomyces euteiches" f.sp. "pisi", which is responsible for pea root rot and is the most economically damaging form of pea root rot. In North America, genetically distinct populations of "A. euteiches" demonstrate host specificity, but such specificity has not been observed in Europe.