664 Breeding and Development of Cold-hardy Roses

Abstract

Without a doubt, roses have been and continue to be an important landscape and greenhouse plant. From the early records, dating back to Egyptian, Roman, and Greek times, roses have played an important societal role. Early attempts at growing roses in Prairie Canada were frequently unsuccessful. The extreme cold in winter, where temperatures of –30 to –40 °C are common, and droughts and heat in the summer greatly reduced the range of plant material, including roses that could be grown. As a result, the Morden Research Centre, part of Agriculture and Agri-Food Canada's Research Branch in southern Manitoba, initiated a series of projects on the development of hardy landscape plants including roses. Since1929, we have introduced over 130 new landscape plant cultivars to the nursery trade, including 18 cultivars of roses. One of the keys to the success of the program was the incorporation of cold tolerance originally obtained from Rosa arkansana, a prairie native. This has led to the development of the `Parkland' rose series. This group of plants flowers repeatedly, are hardy to USDA zone 3, root from softwood cuttings, and are available in a variety of colors. Highlights of these will be presented. More recently, emphasis has been placed on developing breeding strategies to improve disease resistance. Major diseases affecting roses include black spot (Diplocarpon rosea), powdery mildew (Sphaerotheca pannosa), and rust (Phragmidium sp.). Details of the current breeding protocols will be outlined as well as results from a series of trials established to elucidate the influence of environment and genotype on disease expression. Cooperative disease monitoring trials (Canada and Sweden) were established and results will be presented.