Use of cultivars resistant to high soil temperature could improve the performance of urban trees. The objective of this project was to examine selections of red maple (Acer rubrum L. and A. x freemanii E. Murray) for genotypic differences in resistance to root-zone heat stress. Development of roots and shoots from rooted single-node cuttings of seven genotypes grown in solution culture was optimal at about 28C. Shoot extension stopped within 3 weeks and terminal buds formed on plants of all genotypes at 36C. In a second experiment, the influence of 34C root-zone temperature on development varied significantly among six genotypes. Formation of terminal buds at 34C was observed only on plants of cv. Morgan and cv. Red Sunset. The reduction in new dry matter at 34C compared to plants at 28C ranged from 21% for cv. Schlesinger to 69% for cv. Morgan. We conclude that genotypes of red maple differ in resistance to high root-zone temperature.
A survey of Georgia homeowners provided insights about their use of fertilizers and pesticides. Knowledge of current homeowner practices is needed to develop a best management practices manual to be used by Master Gardeners to train the general public through the existing outreach programs. The objective of the training program is to reduce nutrient runoff and garden chemicals and improve the quality of surface water in urban water-sheds. Results showed three of four homeowners did their own landscaping and, therefore, fully controlled the amount of applied chemicals and the area of application. Fertilizers were primarily applied to lawns, but a high percentage of homeowners also applied them to trees, shrubs, and flowers. Insecticides were applied by a larger percentage of homeowners than herbicides. Control of fire ants (Solenopsis invicta) was likely the reason behind the frequent use of insecticides. The desire for a weed free lawn was the plausible motivation behind the use of herbicides, which were used mostly on lawns. Fungicide use was infrequently reported by Georgia homeowners. The pattern of fertilizer and pesticide use suggests that the developed manual should emphasize techniques and cultural practices, which could lower the dependence on chemicals, while ultimately assuring the desired appearance of turf and ornamental plants.
Urban landscape ecology is a new interest that crosses several disciplines: botany, forestry, horticulture, sociology and land use planning. University forest environs are often the most degraded; foot traffic, development and a shortage of funds for significant tree plantings are main culprits. SFASU lies in the pineywoods region of east Texas and is known as the “university among the pines.” The campus is blessed with many patriarch pines and hardwoods. Computer-assisted drafting (CAP) and Geographic Information Systems(GIS) platforms are being utilized to map the campus vegetation. A 1992 vegetative analysis, when compared to similar studies in 1971 and 1983, indicates a loss in species diversity and frequency with little change in basal area. AutoCad*, LandCadd*, and Studio-3D* are being integrated into a multi-disciplinary project to develop a three-dimensional biotic/abiotic model of the campus. That model will be used as a “fly-through” visualization tool to develop forest conservation strategies most likely to succeed in a sustainable fashion.
Tree transplanting practices influence plant survival, establishment, and subsequent landscape value. However, transplanting practices vary substantially within the horticultural industry. Of particular importance is the location of the root collar relative to soil grade at transplant. The objective of this study was to determine the effects of factorial combinations of planting depths, root collar at grade or 7.6 cm either above or below grade, and soil amendments on container-grown (11 L) Quercus virginiana Mill. Soil treatments included a tilled native soil (heavy clay loam, Zack Series, Zack-urban land complex, fine, montmorillonitic, thermic, udic paleustalfs), native soils amended with 7.6 cm of coarse blasting sand or peat that were then tilled to a depth of 23 cm, or raised beds containing 20 cm of sandy loam soil (Silawa fine sandy loam, siliceous, thermic, ultic haplustalfs). A significant (P ≤ 0.05) block by soil amendment interaction occurred for photosynthetic activity. Incorporation of peat significantly decreased the bulk density of the native soil. Planting depth had no significant effect on photosynthetic activity or stem xylem water potential at 3 months after transplant. Soil water potentials did not statistically differ among treatments.
Southern Nevada Master Gardeners (MGs) donate 50 hours annually to educational and service projects. These volunteers respond to community needs by developing and staffing horticultural projects under UNCE supervision. In Las Vegas, 20 such projects exist. Some are more energy and information intensive than others. Mojave Guides are docents at the Desert Demonstration Garden, a part of the Las Vegas Springs Preserve, not Extension. They commit to a shift at the garden, providing information to visitors. While they are directly supervised by garden staff, the hours they contribute are Master Gardener hours. These volunteers receive training in desert flora from gardens staff and participate in seminars on selected topics. The MG Orchard Team operates a teaching orchard at the Center for Urban Water Conservation in North Las Vegas. These volunteers maintain hundreds of fruit trees and grape vines. They receive training on topics related to fruit trees and orchard management. This project began in 1996. Since 2002, they have been formalizing their organization using the logic model and SWOT analysis. Many members work weekly at the orchard and take the produce to a local farmers market. This raises funds for the orchard and is an opportunity to teach the community about desert horticulture. Project PLANT volunteers work at the Red Rock National Recreation Area visitor center and grounds. They are docents who also learn about and maintain the native plants there, and prevent infestations of invasive weeds which threaten the area. Their monthly meetings include training on topics related to the project. These projects are successful because of the MGs themselves. They grew out of interest and continue because the volunteers have drawn commitment from others.
The genus Ulmus contains numerous stress-tolerant species, especially those from areas of China with climates similar to various regions of the United States. Lace-bark elm, Ulmus parvifolia, the true Chinese elm, has an extensive temperature distribution range in China and offers great promise as a street tree. The high resistance of this elm to Dutch elm disease and other elm problems makes it an excellent tree for urban landscapes. Two new U. parvifolia cultivars, Athena® and Allee®, are not cold hardy for northern climates and there is a need for new cold hardy lace-bark elms. Screening thousands of seedlings for cold hardiness, upright form, beautiful bark characteristics, and larger leaves will bring the most desirable U. parvifolia cultivars into the green industry. We determined that seed dormancy and the percentage of seed germination of four selected lacebark elms after 2 and 4 weeks were >30% and >50%, respectively. There were significant differences in stem cold hardiness among new lace-bark elms from China (about –32 to –40 °C). Laboratory determination of cold hardiness can provide great advantages over years of field testing. Response to the outdoor temperature in December, January, and February on a seed cold hardiness freezing test showed significant reduction in seed germination, especially at –30 °C. Freezing test of seeds to –40 °C, resulted in lt 50 of –3 to –5 °C in December, so, it is less likely that these U. parvifoilia will become invasive in northern latitudes. Invasiveness of these U. parvifolia for higher zones, e.g., 6–8 could be greater and selection of these elms is suitable for zones 5 and lower. Planting these elms in zones 4, 3, and 2 will give us useful information regarding their winter performance.
) to reduction in shoot growth and decline of the trees ( Ortega et al., 2006 ). In some cases, root malformation may lead to the death of the plant. Survival and the resilience of nursery seedlings to transplant stress depends on their ability to
standard; Plants suited for espalier training; Sample pruning specifications; A schedule for training shade trees in the urban landscape (“Trees are like children; they require about 25 years of training to create good, solid structure that will last them a
measurements. In late Nov. 2006, trees were transplanted 2 m apart into a single nursery row of Groseclose silt loam soil (clayey, mixed, mesic Typic Hapludults) with a pH of 6.2 at the Urban Horticulture Center. Planting holes were dug with a 61-cm tractor
shrubs), we noted whether there was overlap (e.g., tree over a shrub). Consequently, landscape material percentage could exceed 100% of the landscapable area. Thus, our data collection method accounted for landscape layers which are often ignored in urban