Flowering, Drought and Disease Tolerance, and Landscape Performance of Landscape Roses Grown under Low-input Conditions in North Central Texas

Abstract

<jats:p>Landscaping today involves the struggle to balance aesthetically pleasing plants while minimizing the impact on the environment, reducing water usage, decreasing fertilizer use, and eliminating or significantly reducing pesticide usage. Roses (<jats:italic>Rosa</jats:italic> sp.), although seen as challenging plants, remain the most popular flowering shrub in the United States. The identification of new cultivars that combine beauty, pest and disease resistance, and drought tolerance are important to Texas landscapes. Sixty roses were assessed over a 3-year period to determine flowering, drought tolerance, disease resistance, and overall landscape performance in minimal-input gardens in north central Texas. Atypical weather during the study had a significant impact on performance. A 2-year drought (2010–11) was accompanied by the hottest summer on record (2011), which included a record number of days of at least 100 °F or higher. As a result, supplemental irrigation was provided three times both summers. Roses generally fared well under these conditions and survived the drought. Flowering was most abundant during the spring and fall, and it was least abundant in the summer. Powdery mildew [PM (<jats:italic>Sphaerotheca pannosa</jats:italic> var. <jats:italic>rosae</jats:italic>)] was a minor problem. Nine of 60 cultivars developed no visible symptoms of PM during the study. Most PM occurred in Spring 2010, with very little found after June; none was found in 2011. Black spot [BS (<jats:italic>Diplocarpon rosae</jats:italic>)] was serious for some cultivars, but most were BS-free; RADrazz (Knock Out<jats:sup>®</jats:sup>) and Lady Banks White had no observed BS during the study. BS occurred mostly in May, June, and November. Overall landscape performance ratings were high, with 23 cultivars having a mean landscape performance rating equal to or better than the Belinda’s Dream standard. The best-performing cultivars were RADrazz (Knock Out), RADcon (Pink Knock Out<jats:sup>®</jats:sup>), RADyod (Blushing Knock Out<jats:sup>®</jats:sup>), WEKcisbaco (Home Run<jats:sup>®</jats:sup>), and Alister Stella Gray. This study was able to identify many other highly performing roses in north central Texas.</jats:p>

Landscape Performance of Buck Roses under Minimal-input Conditions in North-central Texas

“…Disease pressure was highest in the spring, with a recurrence of black spot in the fall, and virtually no disease pressure during July and August. Landscape performance of Buck roses was usually consistent with previous rose cultivar trials in northcentral Texas (Harp et al, 2019;Mackay et al, 2008;Zlesak et al, 2017). In this study, several rose cultivars performed well, especially April Moon, Freckles, Carefree Beautyä, Red Dream, Square Dancer, Prairie Breeze, and Country Dancer, whereas others performed poorly.…”

“…Landscape performance and bloom patterns mimicked previous studies of roses in north-central Texas (Harp et al, 2019; Mackay et al, Table 3. Monthly ratings, averaged across all years, for landscape performance, bloom number, bloom coverage, drought rating, black spot, and powdery mildew for Buck roses evaluated over 3 years under minimal-input conditions in northcentral Texas.…”

“…However, in 2010 and 2011, northcentral Texas suffered through extreme heat, with 25 and 70 d above 100°F, respectively, and below normal precipitation that led to exceptional drought conditions. This was the most intense drought in recorded Texas history (Harp et al, 2019;Nielsen-Gammon, 2011). To prevent plant death, we applied supplemental irrigation sufficient to bring soil moisture levels to field capacity, three different times in 2010 and again in 2011, during July and August.…”

“…Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the authors, Texas A&M University-Commerce, Texas A&M University, Texas A&M Agri-Life Extension Service, University of Wisconsin-River Falls, the Houston Rose Society, Arborilogical Services, Vital Earth Resources, or the city of Farmers Branch, and does not imply its approval to the exclusion of other products or vendors that also may be suitable. of drought stress (Harp et al, 2015(Harp et al, , 2019Pinior et al, 2005). To provide an accurate assessment of drought stress performance under normal summer conditions, we also collected drought stress ratings through 2012.…”

“…Unfortunately, other than Carefree Beautyä, little information is available regarding the use of Buck roses in warmer climates. Identifying roses with strong landscape performance, resistance to pests and diseases, and a tolerance for the heat and drought common in north-central Texas can be difficult (Harp et al, 2019;Mackay et al, 2008;Zlesak et al, 2017). The objective of this study was to evaluate a selection of Buck roses under minimalinput conditions in north-central Texas.…”