Since it is unlikely that crop coefficients will be established for landscape plantings, a method to estimate landscape water requirements is proposed. By evaluating three factors that significantly influence water use-species planted, vegetation density, and site microclimate-and assigning numerical values to each, an estimate of a landscape crop coefficient (or landscape coefficient, KL) can be calculated. An estimate of evapotranspirational water loss for landscapes is then the product of the landscape coefficient multiplied by the reference evapotranspiration. This paper presents values for the above three factors and discusses the rationale for each. Examples using the landscape coefficient formula are included, as well as a discussion of special considerations relative to its use.
L.R. Costello, N.P. Matheny, and J.R. Clark
Ji Jhong Chen, Yuxiang Wang, Asmita Paudel, and Youping Sun
accumulate to toxic levels in plant cells. Salinity tolerance varies among plant species, and selecting salt-tolerant plants and using them in landscapes can be sustainable. Salinity-tolerant plants are usually identified by manually irrigating plants with
Clara E. Trueblood, Thomas G. Ranney, Nathan P. Lynch, Joseph C. Neal, and Richard T. Olsen
The genus Hypericum L. (Hypericaceae Jussieu) contains ≈400 species of small trees, shrubs, and herbs, including many ornamental plants that are grown for their attractive, yellow flowers and brown to dark red berries and capsules ( Huxley et al
Yan Chen, Ronald E. Strahan, and Regina P. Bracy
reduce aesthetic quality of landscape beds. It is found in nearly all soil types and thrives in irrigated areas and tends to become established where other weeds are controlled. It is fast growing. A single plant is capable of producing 19,000 to 22
Catherine A. Paul, Greg L. Davis, Garald L. Horst, and Steven N. Rodie
Water conservation in a landscape is an important issue because periodic water shortages are common in many regions of the world. This increases the importance of specifying landscape plants that require less water and matching the plant to site microclimates. Our objectives were to establish water-use rates for three herbaceous landscape plants and to determine the level of water reduction these plants can tolerate while maintaining both visual and landscape quality. Water use rates were determined for Schizachyrium scoparium (Little bluestem), Hosta spp. (Hosta) and Festuca cinerea `Dwarf' (Dwarf blue fescue) in studies using pot lysimeters at the Univ. of Nebraska Horticulture Research Greenhouse facility. Each lysimeter was watered to saturation, allowed to drain to field capacity, and weighed. The lysimeters were weighed again 24 h later, and the process was repeated to determine daily evapotranspiration. Results indicated that hosta used less water than dwarf blue fescue and little bluestem. In a subsequent study to compare the relative effects of withholding irrigation among these species, seven groups of five replicates of each species were grown in 1 peat: 0.33 vermiculite: 0.66 soil: 1 sand (by volume) in 7.6-L containers. Each container was watered to saturation, allowed to drain for 24 h to reach field capacity, and allowed to dry down in 10-day increments. Results of the dry-down study indicated that little bluestem maintained the best visual quality for the longest duration of drought, followed by dwarf blue fescue and hosta in decreasing order of visual quality.
R.A. Mirabello, A.E. Einert, G.L. Klingaman, and R.W. McNew
To examine the effects of mulching and fertilization on nutrient availability and plant growth in landscape beds, plots were established using four mulches (cottonseed hulls, cypress wood, pine bark, pine straw) and three fertilizer application methods (granular, liquid, time-release). Fertilizer was applied either below the mulch on the soil surface or over the mulch surface. Marigolds, Tagetes erecta L., were planted during the summer, followed by pansies, Viola×wittrockiana Gams, during the winter. Applied fertilizers, existing soil nutrients, and water-soluble nutrients from the new mulch provided an adequate supply of nutrients for marigold growth. Placement of fertilizer above or below the mulch did not affect marigold growth. Pansy growth was limited by depletion of soil N during the marigold season and by leaching of applied nutrients in the winter while plants were not actively growing. Mulch lowered soil temperatures and slowed pansy recovery in the spring. Pine straw allowed soil temperatures to rise earlier in the spring and improved pansy growth.
Pragati Shrestha and Jessica D. Lubell
The sustainable landscape featuring native plants is a rapidly expanding trend in horticulture. Native plants support wildlife, including pollinators, and are not invasive ( Tallamy, 2007 ). Some of the most popular and widely used plants for
Melvin P. Garber
Landscape architects occupy a strategic position in the landscape industry; yet, they have not been generally considered an important customer group by nurserymen. They influence selection of plant material for commercial, government, and residential landscapes and are generally the first to know what will be in demand. A recent survey of Georgia landscape architects found they specify $85 M of plants. This compares to the $200 M estimate for the 1989 wholesale value of nursery stock produced in Georgia. In addition, 60% of the landscape architectural firms influence which production nursery supplies plants by determining or recommending the production nursery where the landscape contractor obtains plants. More importantly, 92% of the large firms, which account for 67% of the dollar value, are involved in selection of the production nursery. The results provide the first quantitative estimate of the influence of landscape architects on nurserymen and suggest that nurserymen should view landscape architects as important customers.
Bruno C. Moser
Information on the Internet relative to the landscape and nursery industries is rapidly expanding. However, finding reliable sites on subjects of interest to the field of commercial landscape horticulture is a difficult task. PLANT: Purdue Landscape and Nursery Thesaurus, is an extensive database of links to Internet information for professional landscape contractors/managers and nursery growers in Midwest and Northeast states. PLANT currently consists of 21 independent pages on topics from “Computer Software” to “Winter Hardiness”, with >2500 links to appropriate Internet information. A search mode allows one to search the database by key words as well. This extension-based tool is also an excellent resource for class assignments in the area of ornamentals and landscape horticulture. As a work in process, PLANT is regularly updated and expanded to provide multiple sources if Internet information on topics of interest to the landscape and nursery industries. PLANT can be found at bluestem.hort.purdue.edu/plant/.
Jayesh Samtani, Gary Kling*, and David Williams
Conventional herbicide applications to container-grown landscape plants, often requires multiple spray applications of herbicides in a growing season and presents problems such as non-uniform application, leaching, run-off, environmental pollution, worker exposure and phytotoxicity to the landscape plants. The use of an organic herbicide carrier could help reduce some of the problems associated with spray applications. Landscape-leaf waste pellets were evaluated as a preemergent herbicide carrier for container-grown landscape plants. Isoxaben, prodiamine and pendimethalin were applied to Chrysanthemum × grandiflorum `Lisa', Euonymus fortunei `Coloratus' and Spiraea japonica `Neon Flash', at rates of 1.12, 2.25, and 2.25 kg·ha-1 active ingredient, respectively, with either water or landscape leaf waste pellets as a carrier. Portulaca oleracea, Senecio vulgaris, and Setaria faberi were seeded following treatment application. Visual ratings on efficacy and photoxicity to landscape plants, and shoot fresh and dry biomass were determined for both weeds and crop plants. Landscape leaf pellets served as an effective carrier for application of prodiamine and pendimethalin and combinations of these herbicides with isoxaben in controlling weeds. Leaf waste pellets as a carrier produced equivalent weed control and phytotoxicity ratings to conventional spray application of these herbicides, on both Chrysanthemum and Euonymus. The pellets did not make a consistently effective carrier for the application of isoxaben alone. Application of herbicides on leaf pellets could result in more uniform herbicide applications, minimize loss of herbicides to the environment and reduce the risk of herbicide contact with nursery workers.