Oidium ocimi has been reported on Ocimum sanctum and 0. tenuiflorum (26, 27). But had been stated that 0. ocimi is insufficiently known (elabo rate morphological data unavailable) (28). Euoidium labiatarum has also been reported on 0. sanctum (29). Oidium ocimi-sanctum has also been reported on 0. santwn (30). But this species clearly differs from our description since appressoria in this case are nipple shaped whereas in our case they are clearly lobed. Molecular analyses indicated that the fungus on 0. basilicum belongs to a distinct clade composed