If you've ever grown roses, you've most likely seen disease damage and have done your share of protective spraying. Black spot and powdery mildew attack the foliage, and Alternaria petal blight can disfigure the flowers. Disease-resistance is a highly valuable trait. Researchers at Texas A&M University are growing 114 rose cultivars without pesticides and evaluating their resistance to disease. During this past season, 27 rose varieties were rated as resistant to Black Spot, 69 varieties were resistant to powdery mildew, and 51 varieties were resistant to Alternaria petal blight. Of the 114 rose cultivars, eleven varieties showed effective resistance to all three diseases. These are the varieties to add to your rose garden this spring: Caldwell Pink, Red Cascade, Westerland, Cramoisi Superior, Sea Foam (at left), Easy Going, Marechal Niel, Lafter, Pearl D'or, Red Ribbon, and Comtesse du Cayla.
Article published on June 23, 2008.