The Ebony series of crepe myrtle ( Lagerstroemia indica ) cultivars includes several (Ebony Embers, Ebony Fire, Ebony Flame, Ebony Glow, and Ebony and Ivory), marketed today under the Black Diamond ® ...brand. These are relatively new crepe myrtle cultivars unique for their dark foliage, but with little information concerning their performance in north-central Texas, especially in low-input landscapes. The study was conducted from 2014 to 2017 at three locations in north-central Texas with three soil types, an acidic fine sandy loam, a neutral pH silt loam, and an alkaline heavy clay. Although soils and environmental conditions caused variations between sites, overall performance among cultivars was consistent across all study sites, with Centennial Spirit having better landscape performance than any of the Ebony cultivars tested. ‘Ebony and Ivory’ and ‘Ebony Blush’ had the overall lowest landscape performance. Ebony cultivars grew more slowly, had fewer blooms, and were more susceptible to powdery mildew than Centennial Spirit. While the trees may perform better in more intensively managed landscapes, the Ebony cultivars did not perform as well as Centennial Spirit in low-input landscapes in north-central Texas.
Griffith Buck (Iowa State University) bred roses ( Rosa sp.) to survive long, cold winters and hot, humid summers yet still retain their foliage without fungicides. Unfortunately, there is little ...known about the performance of Buck roses in the southern United States. Thirty-eight Buck rose cultivars were evaluated for flowering, disease resistance, drought tolerance, and overall landscape performance in alkaline soils with no fertilizer, no pesticides, and only limited irrigation. Flowering occurred on a bimodal basis, with the highest per plant mean bloom number (16.3 blooms) and bloom coverage (9.7%) in April, and a second flowering in the fall, with 13.7 blooms per plant and 6.9% bloom coverage in October. Drought stress symptoms were most evident in October, with a wide range of symptom severity across cultivars. Black spot ( Diplocarpon rosae ) and powdery mildew ( Podosphaera pannosa ) incidence were rare across all roses and years. Landscape performance scores, rated using a 0 to 10 scale with 10 representing a perfect plant and 0 a dead plant, were highest in April (6.5) and lowest in June (4.6) and July (4.6). Landscape performance was not correlated with bloom number or coverage. While unable to recommend many of the Buck roses for north-central Texas, the cultivars April Moon and Freckles, and possibly a few other roses, can join Carefree Beauty™ (BUCbi) as recommended roses for the area.
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 ( Rosa 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 ( Sphaerotheca pannosa var. rosae ) 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 ( Diplocarpon rosae ) was serious for some cultivars, but most were BS-free; RADrazz (Knock Out ® ) 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 ® ), RADyod (Blushing Knock Out ® ), WEKcisbaco (Home Run ® ), and Alister Stella Gray. This study was able to identify many other highly performing roses in north central Texas.
Abstract
Honeybees (Apis mellifera L.) are important pollinators and will selectively forage on crepe myrtle (CM) during the summer months. Unfortunately, CM pollen can become contaminated with ...pesticides used to control insects, especially crepe myrtle bark scale (Acanthococcus lagerstroemiae Kuwana). An experiment was conducted in July and August of 2019 and 2020 to compare honeybee visits to CM among four cultivars (‘Natchez', ‘Tuscarora', ‘Ebony Fire', and ‘Pocomoke') at an isolated location, and within a single cultivar series (Ebony) near other pollinator-friendly plants. ‘Natchez' had the most honeybee visits per tree, averaging 1.4 visits per 75 seconds per tree per day in 2019 and 1.2 visits per 75 seconds per tree per day in 2020, followed by ‘Tuscarora' with 0.8 and 0.4 honeybee visits per 75 seconds per tree per day, in 2019 and 2020, respectively. In 2020, there was a significant, moderate correlation (P< 0.001, r = 0.51) between bloom number and honeybee visits, with ‘Natchez' (158.9) and ‘Tuscarora' (148.2) having more average blooms per tree than ‘Ebony Fire' (35.6) and ‘Pocomoke' (35.7). Landscape environment and proximity to pollinator-friendly plants did not affect honeybee visits. CM are an important foraging resource for honeybees in the summer, and honeybees have a strong preference for cultivars with large, productive bloom clusters.
Index words: pollinators, crepe myrtle bark scale, Acanthococcus lagerstroemiae, crepe myrtle
Species used in this study: Crepe myrtle, Lagerstroemia indica L.; Lagerstroemia × faurei; Honeybee, Apis mellifera L.; American bumblebee, Bombus pensylvanicus De Geer.
Green roofs provide multiple environmental and economic benefits, such as roof surface temperature reduction, reduced internal cooling needs, storm water management, and extended life span of roofing ...materials. However, green roof substrates must be relatively lightweight, so it is typically coarse with limited water holding capacity. We hypothesize the physical characteristics that make the substrates successful on a roof are likely to reduce seed germination. For this study, we tested the germination of three perennial species and one annual: shasta daisy ( Leucanthemum × superbum ), yarrow ( Achillea millefolium ), and indian blanket ( Gaillardia pulchella ), and pinto bean ( Phaseolus vulgaris ) (as a control) across five different substrates: peat/perlite/large expanded shale, compost/sand/expanded shale, compost/black dirt/expanded shale, compost/expanded shale, and peat/perlite (control). Substrate physical and chemical properties were analyzed, and a germination test conducted using a randomized complete block design, with each species/substrate combination appearing once per block. Germination was defined as seedling emergence, and monitored every 7 days for 28 days. Pinto bean had the highest germination (76.2%) across all substrates, compared with 43.4% for indian blanket, 40.4% for yarrow, and 23.0% for shasta daisy. Seed germination, across all species, was lower in green roof substrates. Germination success was very strongly correlated with seed length, seed width, and seed area, while no relationship was found between seed germination and substrate pH or electrical conductivity (EC). Therefore, it is likely that the physical characteristics of green roof substrates create poor conditions for seed germination.
Landscape roses ( Rosa sp.) are popular flowering shrubs. Consumers are less willing or able to maintain landscape beds than in years past and require plants that are not only attractive, but ...well-adapted to regional climatic conditions, soil types, and disease and pest pressures. Marketing and distribution of rose cultivars occurs on a national level; therefore, it is difficult for U.S. consumers in the U.S. Department of Agriculture (USDA) Plant Hardiness Zones 3 to 5 to identify well-adapted, cold-hardy cultivars. Identifying suitable cultivars that have strong genetic resistance to pests and disease and that will tolerate temperature extremes without winter protection in the USDA Plant Hardiness Zones 3 to 5 is of tremendous value to consumers and retailers in northern states. Twenty landscape rose cultivars, primarily developed in north-central North America, were evaluated at five locations in the United States (three in the north-central United States, one in the central United States, and one in the south-central United States) using the low-input, multiyear Earth-Kind ® methodology. Six roses had ≥75% plant survival at the end of the study and were in the top 50% of performers for overall mean horticultural rating at each of the three north-central U.S. sites: ‘Lena’, ‘Frontenac’, ‘Ole’, ‘Polar Joy’, ‘Sunrise Sunset’, and ‘Sven’. Five of these six roses met the same criteria at the central United States (exception ‘Lena’) and the south-central United States (exception ‘Polar Joy’) sites. Cultivar, rating time, and their interaction were highly significant, and block effects were not significant for horticultural rating for all single-site analyses of variance. Significant positive correlations were found between sites for flower number, flower diameter, and overall horticultural rating. Significant negative correlations were found between flower number and diameter within each site and also between black spot ( Diplocarpon rosae ) lesion size from a previous study and overall horticultural rating for three of the five sites. Cane survival ratings were not significantly correlated with overall horticultural rating, suggesting some cultivars can experience severe winter cane dieback, yet recover and perform well. Data from this study benefit multiple stakeholders, including nurseries, landscapers, and consumers, with evidence-based regional cultivar recommendations and breeders desiring to identify regionally adapted parents.
Abstract
Although development of low (extensive) and high (intensive) maintenance green roof systems has progressed significantly, studies on the function of the growing substrate as a living ...constituent are lacking. The objective of this review paper is to summarize current scientific knowledge on the components, composition, and characteristics of green roof substrates and to identify future research needs. Due to variations in climate and desired plant types, there is no universal growing substrate. An appropriate substrate is expected to provide permanent physical support for plants and possess a fine balance between free drainage and adequate plant available water and nutrient retention. Typical substrate components include minerals in natural or modified forms such as sand, lava rock, or expanded shale, clay and slate; recycled waste materials like crushed bricks or tiles, crushed or aerated concrete and subsoil; stabilized organic matter such as composts; and plastic materials and slow release fertilizers. Proportions of components vary among substrates based on target vegetation, green roof type, and other considerations. Better green roof management for maximum benefits will require characterizing, quantifying and understanding the impacts of plant species and building attributes such as aspect, slope, height and heating on substrate performance, and should be considered for future research.
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