| You are way ahead of me but I was so intrigued by the question I went looking myself. A rose progeny to study this trait has been produced by David Byrne and it is currently being used to develop a genetic map at Clemson University - a Genomics Institute in South Carolina. I couldn't access any info and there may be none published for the public domain. Found out some stuff though. They have done some trialling and come up with this list - Black Spot – resistant: Hybrid tea: ‘Pride N Joy’ Floribunda: ‘Sexy Rexy’ Grandiflora: ‘Prima Donna’ Black Spot and Powdery Mildew-moderately resistant: Hybrid tea: ‘Duet,’ ‘Eiffel Tower,’ ‘Grand Slam,’ ‘Jamaica,’ ‘Matterhorn’ Floribunda: ‘Golden Slipper,’ ‘Saratoga’ Grandiflora: ‘Camelot,’ ‘John S. Armstrong,’ ‘Pink Parfait,’ ‘Queen Elizabeth’ Shrub roses: ‘All That Jazz,’ ‘Carefree Wonder’ Black Spot, Powdery Mildew and Cercospora Leaf Spot –resistant: Rugosa roses: ‘Blanc Double de Coubert,’ ‘Fru Dagmar Hastrup’ (‘Frau Dagmar Hartopp’) ‘Rugosa Alba,’ ‘Topaz Jewel’ Alba rose: ‘Alba Semi-Plena’ This came from Ohio University - under ideal conditions of leaf wetness, humidity and temperature the spores can germinate and infect in 1 day, cause symptoms in 4 to 5 days, and produce new spores that can infect additional leaf, flower and cane tissue within 10 to 11 days. Spores are easily spread to new locations by air currents. This from the University of Maine - the spores must be wet for at least 7 hours before they can germinate disease develops most rapidly at about 75F. The site below has a detailed list of blackspot resistant roses and includes those that are highly susceptible. You may already know all this but I didn't - thanks for posting an interesting question. A site that may be of interest - http://www.aces.edu/pubs/docs/A/ANR-0505/ |