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Xiaoya Cai, Terri Starman, Genhua Niu, Charles Hall and Leonardo Lombardini

in the world, and garden roses are one of the most popular and widely cultivated flowering plants. Moreover, some are valued for having ornamental fruit, and they can be used as hedges, screens, and groundcovers. Their cultivation, however, presents

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Ockert Greyvenstein, Terri Starman, Brent Pemberton, Genhua Niu and David Byrne

Overall sales of garden roses have been declining over the past 20 years in the United States due, in part, to the lack of widely adapted cultivars to heat, drought, and salt stress in landscape environments ( Byrne et al., 2010 ). Conversely, an

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Genhua Niu, Terri Starman and David Byrne

and leaves ( Niu et al., 2008 ). Garden rose ( Rosa spp.) is one of the most economically important and popular ornamental plants in the world. Rose has been traditionally categorized as a salt-sensitive species with salt injury reported within a

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Xianqin Qiu, Hao Zhang, Hongying Jian, Qigang Wang, Ningning Zhou, Huijun Yan, Ting Zhang and Kaixue Tang

background of modern varieties is relative narrow ( Liu and Liu, 2004 ; Matsumoto et al., 1998 ). The roses obtained before the breeding of ‘La France’ in 1867, the first Hybrid Tea rose, are generally called old garden roses ( Cairns, 2003 ). The beauty of

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Beth Clendenen, B.K. Behe and K.L. Bowen

Eleven rose cultivars were field planted and evaluated weekly for disease, defoliation, and overall vigor in order to compare natural resistance to blackspot (Diplocarpon rosae). Alternative treatments were also compared for efficacy in low-maintenance disease control. Treatments included a bimonthly application of chlorothalonil, a bimonthly application of a horticultural oil, an application of chlorothalonil based on rain events, and a no-treatment control. Cultivars showed significant differences in disease severity, defoliation, and overall performance, with old garden rose varieties showing more natural disease resistance than modern susceptible varieties included in the study. Chlorothalonil applied on a 14-day spray schedule did provide a significant decrease in blackspot disease severity when compared to other treatments. A significant incidence of secondary disease including Cercospora rosicola and Botrytis cinerea occurred on old garden rose varieties. No treatment differences were found for these diseases. `Belinda's Dream', `The Fairy', and `Red Mediland' ranked highest in overall performance throughout the season.

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W. A. Mackay, C.M. McKenney, P.F. Colbaugh, S.A. George, J.J. Sloan and R.I. Cabrera

To enlarge the palette of environmentally-responsible landscape plants, 117 garden rose cultivars were evaluated under minimal input conditions. Other than mulching and irrigation, no other inputs were provided, including no fertilization and no pesticide applications. Plants were established in completely randomized blocks with four reps in the spring of 1998 with data collection beginning in 2000 and continued through 2002. Data on overall performance (an index comprised of flower number, percent of plant covered with flowers and plant growth) and relative chlorophyll content were collected the first and third week of each month from April through October. Disease ratings or incidence ratings were collected for Diplocarpon rosae Wolf (black spot), Alternaria sp. (petal blight) and Sphaerotheca pannosa (powdery mildew). Statistical analysis was performed on the mean data for all dates. `Knockout' was the top rose for overall quality with little or no disease observed, high foliage quality, and continuous flowers from spring until late in the fall. `Knockout' also ranked among the top rose cultivars in terms of overall nutrient concentrations (N, P, K, and Fe) in new growth tissue. Most of the hybrid tea roses such as `Peace' and `Double Delight' died in at least three blocks due to disease and a lack of vigor.

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Valentina Scariot, Aziz Akkak and Roberto Botta

Six polymorphic sequence-tagged microsatellite sites (STMSs) were used to characterize 65 accessions of old garden roses [OGRs (Rosa L. spp.)] from seven botanical sections and 13 horticultural groups. Aims of the study were to define the genetic profiles of accessions and to provide information useful for the classification and pedigree reconstruction of OGRs. In roses, a precise botanical classification is difficult due to repeated hybridization carried out in breeding; OGRs are classified in horticultural groups on the basis of their original parentage or of their morphological traits. A total of 82 alleles were detected at six loci. The number of alleles per locus ranged from six to 21, with an average of 13.7 alleles per locus. A dendrogram was constructed by cluster analysis, displaying the relative genetic similarities between species' accessions, hybrids, and cultivars. Cluster analysis grouped the genotypes into seven major clusters that were substantially consistent with their classification into botanical sections and horticultural groups. Several hypotheses of apportionment of accessions to horticultural groups were evaluated on the basis of the relative position in the dendrogram of the analyzed individuals. Results demonstrated that DNA analyses can contribute to drawing the botanic classification of rose accessions, improving the genetic knowledge on the background of modern rose, and providing the basis for breeding programs.

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W.A. Mackay, S.W. George, C. McKenney, J.J. Sloan, R.I. Cabrera, J.A. Reinert, P. Colbaugh, L. Lockett and W. Crow

garden roses to the very newest shrub roses, and to identify those cultivars that would provide outstanding landscape performance in the southern United States with no fertilizer, pesticides, deadheading or pruning, and with greatly reduced supplemental

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Xuan Wu, Shuyin Liang and David H. Byrne

, public parks, commercial spaces, and residential areas. Garden roses provide aesthetic value throughout the growing season due to both their vegetative and floral production. Plant architecture of roses is linked to flower yield and ornamental value

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Genhua Niu, Denise S. Rodriguez and Lissie Aguiniga

has been conducted on garden roses. Most garden roses are produced by grafting using the T-budding technique ( Pemberton, 2003 ). Different rootstocks are used in various areas in the world in accordance with climatic and soil conditions. For example