[From Modern Garden Roses, by Peter Harkness, p. 138:] The Association of German Nurserymen organizes a competition to select roses likely to withstand different climatic conditions within the country. Each chosen rose is labelled 'Anerkannte Deutsche Rose' (ADR) and can be expected to enjoy a long commercial run.

In contrast, as per Harold Enders:
The abbreviation ADR does not mean "Anerkannte Deutsche Rose" ("Acknowledged German Rose"), but "Allgemeine Deutsche Rosenneuheitenprüfung" which means "General testing of German rose novelties".