2013 ASHS Annual Conference

The concept of using low maintenance landscape roses has become very popular, and cultivars that can handle general landscape maintenance conditions are being developed by rose breeders.  Kordes was an early proponent of trialing their roses under no-spray conditions.  A group of 11 Kordes rose cultivars were field grown under low maintenance conditions which was limited to fertilization, mulching and weed control.  Drip irrigation was provided only for establishment.  The roses were not deadheaded or pruned, nor were they sprayed.  Data was collected monthly for 2 years beginning in April, 2009.  Height and width were measured from which was derived volume. Blackspot infection was estimated using the Horsfall–Barratt scale.  Visual quality ratings were determined for flower quantity and quality, foliage quantity and quality, and plant habit and vigor. The cultivars were Cerise Flower Circus, Cream Flower Circus, Coffee Fruitilia, Cosmos, Escimo, Fortuna Vigorosa, Lions Fairy Tale, Pink Flower Circus, Red Ribbons, Sunrise Vigorosa, and Sweet Vigorosa.  The cultivars were genetically diverse and results were highly variable.  The strongest growing roses were 'Lions Fairy Tale' and 'Escimo'. No clear differences among cultivars were seen for blackspot resistance and there was no strong correlation between blackspot resistance and any growth or quality measurement. 'Lions Fairy Tale', 'Escimo', and 'Cosmos' maintained vigor better through the seasons than the other cultivars. Over time, these three cultivars appear to have more potential than the other cultivars in a low maintenance environment of a subtropical climate, such as found in east central Mississippi.