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BookmarkScienceDaily (Mar. 4, 2009) — Roses have long been a favorite of gardeners, but they often require a lot of work to thrive. And the emphasis on organics has more home gardeners concerned about the environment and reluctant to use pesticides.
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W. A. Mackay of Texas A&M University led a study comparing several varieties of roses to determine which grow best with minimal care under certain conditions. The results were published in the American Society for Horticultural Science journal HortTechnology.
Flower number, flower size, visual estimate of flowering percentage, plant vigor and overall plant performance were rated for 116 varieties of roses from Spring 2000 through 2002. No pesticides or fertilizers were used to grow the roses. Four plants represented each variety, and only varieties with three or four plants surviving the experiment were used in the statistical analysis.
Additional tests were run on a subset of rose varieties to assess their nutrient levels. Monthly recordings were also taken to rate each variety's disease resistance by noting symptoms of petal blight, powdery mildew, and black spot, some of the most common ailments of roses. Plants that were grown on their own roots had significantly better appearance ratings and survival rates than plants that were grafted.
'RADrazz' (Knock Out™) was the best-performing rose overall, which the study contributes to its "vigorous growth and attractive foliage." Trumpeter® was the worst-performing rose. Out of all the roses that performed well in the study, 15 are recommended as low-maintenance for growing in Texas.
The study also found differences in performance between classes of roses, with Polyanthas being best in overall performance and Hybrid Tea roses being worst. Based on the results of this study, selected varieties were chosen for an expanded nationwide study to develop the EarthKind™ collection of roses.
Journal reference:
- Mackay, W.A., George, S.W., McKenney, C., Sloan, J.J., Cabrera, R.I., Reinert, J.A., Colbaugh, P., Lockett, L., Crow, W. Performance of Garden Roses in North-central Texas under Minimal Input Conditions. HortTechnology, 2008 18: 417-422 [link]
