Pentachloro Rose Bengal Yeast Extract Agar Base (PRYES Agar) is recommended for the cultivation and differentiation of nephrotoxin producing strains of Penicillium viridicatum and related species isolated from food in accordance with APHA. This medium was formulated by Frisvad and also recommended by APHA for the cultivation and differentiation of mycotoxin or nephrotoxin producing strains of Penicillium viridicatum and related species. The medium consists of yeast extract, sucrose (YES) as the basal medium and pentachloronitrobenzene and rose bengal and hence the name PRYES.