-tolerant succulents [particularly stonecrop ( Sedum ) species] have been the dominant plant selections for extensive green roof applications ( Getter and Rowe, 2006 ). However, expanding the plant palette available for green roofs is desirable. Green roof vegetation
Erin Schroll, John G. Lambrinos, and David Sandrock
Yann-Jou Lin, Ai-Tsen Su, and Bau-Show Lin
substrate layer, drought, strong winds, and large variations in temperature, so there are many limitations affecting plant selection. Suitable plant species must be heat tolerant, drought tolerant, wind tolerant, and cold tolerant as well as tolerant of
Wayne A. Mackay, Steve W. George, Tim D. Davis, Michael A. Arnold, R. Daniel Lineberger, Jerry M. Parsons, Larry A. Stein, and Greg G. Grant
The Coordinated Educational and Marketing Assistance Program identifies outstanding landscape plants for Texas and provides support for the nursery industry, thereby making superior plants available to Texans. CEMAP funding comes directly from industry and from consumers through the sale of plant tags bearing the Texas Superstar logo. Additionally, the Texas Nursery and Landscape Association and Texas Department of Agriculture is conducting a Texas Superstar publicity campaign. An estimated $10 million in new plant sales have been generated during the first 10 years of this program. Because plants are chosen based on their performance under minimal input conditions, Texas SuperStars greatly reduce their impact on the urban environment.
Dale E. Herman and Lawrence J. Chaput
Woody plant improvement research has been an active program at North Dakota State Univ. (NDSU) for many years. Eighteen cultivars have been introduced since 1986, and ≈10 additional releases are anticipated over the next 6 years. These superior, winterhardy cultivars have increased the inventory of adapted woody plants for landscape use in the northern plains, particularly USDA hardiness zones 3 and 4. Emphasis will be placed on recent introductions and promising plants for potential future release. An extensive, statewide cooperative evaluation program is conducted at seven sites throughout North Dakota and also at the NDSU Research Arboretum near Absaraka.
John A. Juvik
Heliothis zea (Boddle) is one of agriculture's worst insect pests. Reduction in crop productivity and costs for insecticidal control of this cosmopolitan pest cost U.S. agriculture many millions of dollars annually. The sesquiterpenes (+)-E-å-santalen-12-oic and (+)-E- endo- β–bergamoten-12-oic acids isolated from hexane leaf extracts of the wild tomato species, Lycopersicon hirsutum, have been shown to attract and stimulate oviposition by female H. zea. Extracts from other host plants (tobacco, corn, and cotton) also possess attractant/oviposition stimulant activity to female H. zea. Studies are underway to assess the potential use of these and other phytochemicals for the control or monitoring of population levels of H. zea in tomato, corn and cotton fields.
The isolation and structural identification of insect pest oviposition stimulants in horticultural crop species can provide valuable information to plant breeders involved in developing cultivars with improved insect host plant resistance. This information could be used to develop cultivars lacking the chemical cues used by insects for host plant location and recognition. Risks of public exposure to toxic insecticides through consumption of agricultural produce and polluted ground water emphasize the critical need for the development of crop genotypes with improved best plant resistance as a supplementary method of insect pest management in agricultural ecosystems.
Miles Schwartz Sax, Nina Bassuk, and Mark Bridgen
A tissue culture system was developed to clonally propagate a series of hybrid white oaks (Quercus L.) at the plant breeding program of the Urban Horticulture Institute (UHI), Cornell University. From 2014 through 2018, 34 genotypes and 1966 individual explants of UHI hybrid white oaks were trialed to determine their capacity to establish, multiply, and root in a tissue culture environment. UHI hybrid oak genotypes were selected based on their known tolerance to stresses common in the urban environment (drought, alkaline soils, pests, and diseases) and their ornamental qualities. Individual genotype was the single largest factor affecting successful establishment, multiplication, stabilization, and rooting of hybrid oaks in vitro. Thirteen clones of hybrid oaks were identified as having the capacity to stabilize and grow continuously in the multiplication phase. Multiplication efficiency rates were dependent on individual genotype. Stabilized genotypes showed the capacity to be re-established during successive years. The tissue culture process was simplified and refined to make the protocols less labor intensive for laboratory technicians using these methods. This study presents a preliminary and promising method for the clonal propagation of oak species and provides a path for cultivar development for plants belonging to the genus Quercus.
Filip Jovanović, Dragica Obratov-Petković, Ivana Bjedov, Ivana Živanović, Sonja Braunović, Tatjana Ćirković-Mitrović, and Gordana Tomović
To address the issues of taxonomic delimitation and to select the material with desirable traits for horticultural use, a comprehensive study of the total variability of morphological characters of two naturally occurring snowdrop species (Galanthus nivalis L. and Galanthus elwesii Hook.) in the central part of the Balkan Peninsula was conducted. The analyses were performed for 16 quantitative characters of aboveground parts of 630 plants collected at 21 geographical points in the territory of the Republic of Serbia. To identify the trends in morphological differentiation, descriptive, univariate and multivariate statistical procedures were employed. Most of the examined characters exhibited moderate degrees of variability (cv from 10% to 20%) and the values of several characters exceeded the limits of variation stated in literature. Samples were mostly morphometrically homogeneous, with comparatively high similarity; only four populations of G. nivalis from the southern and southeastern part of the country were discrete. It is questionable whether these populations merit formal taxonomic recognition at any infraspecific level, but given their decorative qualities, the selected plants can be introduced into cultivation as horticultural plants.
Julie Guckenberger Price, Stephen A. Watts, Amy N. Wright, Robert W. Peters, and Jason T. Kirby
structural capacity sufficient to support the additional weight. Plant selection for intensive green roofs is vast: within climatic limitations, selected small trees can be successfully integrated into green roof flora if provided sufficient soil depth and
Nina Bassuk and Peter Trowbridge
assessment, appropriate plant selection, soil amelioration, and sound installation and management are followed. The objectives are 1) to gain a firsthand understanding of the heterogeneity of urban and other growing conditions and to know how these various
Carter M. Westerhold, Samuel Wortman, Kim Todd, and Douglas Golick
., 2017 ). The number of homeowners seeking pollinator conservation advice from horticulture retail should rise as well. Knowledgeability of horticulture retail staff in plant selection is an important quality for a garden center to have ( Barton et al