Maybe members Ca`Berta and Andrew can add more information. She had provided the information that 'Caporosso', the other Hybrid Rugosa by Quinto Mansuino, was bred already in 1955. While most of Mansuino's roses were bred in the 1960's-70's, we know from "Le Rose Italiane" by Andrew Hornung that Mansuino was already sowing thousands of seedlings before 1944. As there are no later rugosas by Mansuino, it is quite probable that 'Ibisco' is a contemporary of 'Caporosso'.