To ensurethey get reliable ratings for resistance they do not rogue susceptiblecultivars and run the trial for 2–3 years. The best performing rosesare subsequently replanted in multiple sites to expose them to agreater range of pathogen diversity. Nevertheless, field screeningwill not distinguish the race(s) the plants are resistant to. This typeof screening can be done efficiently using a detached leaf screeningtechnique with specific races in the laboratory [36].