Re-investigation of Erysiphe spp. on Polygonaceae in Iran, Germany, Pakistan, and Russia revealed that hitherto E. polygoni is a complex species. Precise morphological studies along with rDNA ITS and 28S data of fresh specimens as well as an epitype specimen of E. polygoni confirmed that Erysiphe on Rumex spp. differs from that one which infects Polygonum aviculare. With having morphological, molecular, and host range differences in mind, E. rumicicola is introduced here as a new species on Rumex spp. Further studies on possible undecribed species on Polygonaceae must be accomplished.
Darsaraei et al. (Sun,) studied this question.