2013 ASHS Annual Conference

Thirty cultivars of hybrid tea roses, determined from the results of a national survey of consulting rosarians with the American Rose Society, were evaluated under landscape growing conditions at the Gardens of the American Rose Center, Shreveport, LA, from 2009–12. The primary objective of this study was to monitor susceptibility of the selected cultivars for susceptibility to blackspot disease under low fungicide application conditions. Plants were grown using cultural practices adapted from Earth Kind rose recommendations (minimum fertilization, minimum irrigation, compost use in bed preparation). Grade 1 roses budded on 'Dr. Huey' rootstock were planted February 2009. Test plots were located in full sun and roses were spaced 4 feet apart within rows and 6 feet between rows. The experimental design was a randomized complete block with 4 replications of each cultivar. Plants were sprayed with consumer formulations of tebuconazole at the recommended rate in 2009 and 2011 and propiconazole in 2010 and 2012. Fungicides were applied each year in late February, mid to late April, mid June, and late August/early September. Plants were pruned according to recommended hybrid tea practices in February and late August each year. A slow-release 12–6–6 fertilizer was applied annually in late February at 1 lb. N/1000 sq. ft. bed area. Blackspot susceptibility ratings were taken in April, June, August, and October each year. Visual quality ratings to determine landscape appeal were taken at the same time each year. The best roses over the four year period in terms of visual quality were 'Traviata', 'Tahitian Sunset', 'Frederic Mistral', 'Tropicana', 'Pink Traviata', 'Mister Lincoln', 'Olympiad', 'Tiffany', 'The McCartney Rose', and 'Crysler Imperial'. The best roses over the four-year period in terms of blackspot resistance were 'The McCartney Rose', 'Traviata', 'Pink Traviata', 'Tahitian Sunset', 'Tiffany', 'Frederic Mistra'l, 'Mister Lincoln', 'Midas Touch', 'Pope John Paul II', 'Electron', and 'Chrysler Imperial'. The American Rose Society will promote 'The McCartney Rose', 'Pink Traviata', 'Traviata', 'Tahitian Sunset', and 'Frederic Mistral' as Easy Tea Hybrid Tea Roses to their membership starting Fall 2013 and to gardening consumers Spring 2014.