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Michael A. Monterusso, D. Bradley Rowe, and Clayton L. Rugh

Although the economic, environmental, and aesthetic benefits of green roofs have been recognized for decades, research quantifying these benefits has been limited—particularly in the U.S. Green roof usage and research is most prevalent in Germany, but can also be seen in several other European countries and Canada. If green roof installations are to be successful in Michigan and the rest of the U.S., then a better understanding of what specific taxa will survive and thrive under harsh rooftop conditions in this geographic area is required. Nine simulated rooftop platforms containing three commercially available drainage systems were installed at Michigan State University. Eighteen Michigan native plants planted as plugs and nine Sedum spp. planted as either seed or plugs were evaluated over three years for growth, survival during both establishment and overwintering, and visual appearance. All Sedum spp. tested were found to be suitable for use on Midwestern green roofs. Of the eighteen native plant taxa tested, Allium cernuum L., Coreopsis lanceolata L., Opuntia humifosa Raf., and Tradescantia ohiensis L. are suitable for use on unirrigated extensive green roofs in Michigan. If irrigation is available, then other native species are potential selections.

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Sandra B. Wilson, P. Chris Wilson, and Joseph A. Albano

Invasive species have disrupted thousands of acres of natural areas in Florida and appear to have a physiological competitive advantage over native species. The influence of light and temperature on germination was determined for the invasive Mexican petunia (Ruellia tweediana Griseb.) and native wild petunia (Ruellia caroliniensis Steud.). Seeds were collected and germinated in incubators with light or darkness at 15, 24, 33, and 30/20 °C. Light increased germination for each species, except at 15 °C (R. caroliniensis). For R. caroliniensis, highest germination (86% to 94%) occurred at 33 °C and 30/20 °C. Highest germination of R. tweediana (98% to 100%) occurred at 30/20 °C. Studies also were initiated to determine if R. tweediana has a competitive advantage over the native species when grown under wet and dry substrate conditions. Growth and development measurements after 8 weeks under controlled conditions revealed that R. tweediana grown in wet conditions had the greatest dry weight increase as compared to other treatments. Ruellia caroliniensis had higher specific leaf area when grown in wet or dry conditions, as compared to R. tweediana. Throughout the experiment, net CO2 assimilation of R. caroliniensis grown under dry or wet conditions was consistently lower than that of R. tweediana. Shoot nitrogen and phosphorus use efficiencies were generally greatest for R. tweediana plants grown in wet conditions. For shoot nutrient content, significant species × moisture interactions occurred for measured phosphorus (P) and calcium (Ca). When grown in wet conditions, R. tweediana had less shoot P and Ca as compared to dry conditions. For root nutrient content, species × moisture interactions were insignificant for each measured nutrient, with the exception of potassium (K). Potassium use efficiency of R. tweediana roots grown in wet conditions was higher than that of R. tweediana grown in dry conditions and R. caroliniensis grown in wet conditions.

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Rebecca L. Loughner, Daniel F. Warnock, and Raymond A. Cloyd

Western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] collected from greenhouse, laboratory, and native populations were evaluated for resistance to the insecticide spinosad. Individual cut stems of transvaal daisy (Gerbera jamesonii H. Bolus ex Hook. f.) were inoculated with 25 adults from 1 of 9 thrips populations and maintained in isolation chambers. Treatments of no spray, water spray, spinosad at one-half label rate (0.41 mL·L-1) and spinosad at the recommended label rate (0.81 mL·L-1) were applied to the flowers. Three days after treatment, the number of live and dead thrips was recorded. Significantly more thrips were recovered from the control treatments than the spinosad treatments. Thrips survival varied by treatment and insect population. Based on an odds ratio analysis, the likelihood of recovering live thrips was greater in the IL-GH1 (Illinois greenhouse) population than in the NV-N1 (Nevada native) reference population for both spinosad treatments, suggesting resistance to spinosad in the IL-GH1 population. The IL-GH1 population was collected from a greenhouse regularly sprayed with spinosad whereas the NV-N1 population was collected in Incline Village, Nev., on wildflowers with no history of exposure to spinosad. This is the first documented indication of spinosad resistance in a thrips population. In comparison to the NV-N1 reference population, none of the populations collected from laboratory or native nonagricultural environments exhibited evidence of resistance to spinosad. Resistance to an insecticide with a novel mode of action, such as spinosad, indicates the necessity of rotating insecticides and implementing alternative methods of managing western flower thrips. Chemical names used: spinosad including spinosyn A and spinosyn D (Conserve SC).

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Dale E. Kester and Thomas M. Gradziel

Approximately twenty native almond species have been described. Representative germplasm from seven of these are present in UC collections and have been used in crossing. Three specific breeding lines utilizing these species are described. One (1980 series) involved increasing yield potential through selection of high blossom density following gene introgression from Prunus fenzliana. A second involved incorporation of self-fertility, late bloom, smaller tree size, early maturity, high blossom density, and desirable nut characters from Prunus webbii into commercial breeding lines. A self-fertile selection resembling `Nonpareil' has been obtained from this material. The third line involves transmission of a unique thin, netted-surfaced, hard-shell phenotype from Prunus argentea.

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R.D. Quinn and D.J. Haselfeld

We are developing an on-line guide to introduce biology students to the native plants of the Cal Poly campus. It will be used prior to field laboratory exercises, and as a reinforcement after field study. It presents reference information in an interactive and nonlinear manner which encourages students to pursue information in the way that is most interesting to them. The guide is organized by a very simple key that divides plants according to habit (trees, shrubs, vines, grasses, forbs). This simple approach is possible because the guide includes only the 30 common species that students must recognize to do plant sampling exercises. Each species has a screen that displays photographs, line drawings, and a nontechnical narrative. This guide displays the appearance of plants in all seasons, and will be available at all times as a web site. It is particularly useful when laboratories meet in inclement weather or at night. As a web site, it displays the native flora of the Cal Poly campus to the world. The guide was relatively easy to construct with common multimedia equipment. The same approach could be readily employed by any educational program that repeatedly uses the same field site.

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L. G. Albrigo, P. M. Lyrene, and B. Freeman

Abstract

Fruit color of selections of native V. elliotti Chapm. varied from black to blue. Wax on fruit was occasionally found to be globular in form but most often waxes were found to range from flat plates to upright platelets and from horizontal rods to long upright rods. Combinations of wax forms occurred in varying densities on the fruit of native selections. Upright rods and platelets accounted for the blue fruit color. Mature black fruit usually had a limited amount of platelet wax and no rodlet structures. β-Diketones were absent or nearly absent on these mature black fruit. Black fruit had some of the higher weight loss measurements. The paraffin content of the fruit wax was relatively high at one location for some black selections and appeared to reduce weight losses of these selections to levels similar to the bluer selections. Leaves had only globular wax forms, less wax than fruit, and considerable variation in the density of acerate trichomes. Leaf hair density and distribution on leaves was independent of variation in wax forms on fruit.

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James M. Affolter and Marta Lagrotteria

The province of Cordoba in central Argentina is naturally rich in aromatic and medicinal herbs that are in high demand as ingredients in teas and herbal medicines. Most of the herbs sold are harvested from natural populations, and this activity is a primary source of income for families in the Sierra de Cordoba region. As a result of over-collection and other poor harvesting practices, many native plant populations have been reduced in size or extirpated. The economic consequence of the gradual decline of this resource has been a loss of real income in rural areas coupled with a pattern of emigration from small towns to larger cities. PRODEMA is a collaborative effort by universities in Argentina and the United States, with the sponsorship of the Cordoba government, to domesticate and to market the most commercially important species. Horticultural research has focused on the development of propagation techniques and identification and selection of desirable chemotypes.

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Rod Jones and John Faragher

Five members of the Proteaceae and 13 Australian native cut flower cultivars were stored for 35 days under standard conditions at 1C to assess their ability to withstand long-term storage and transport. Protea cynaroides L., Leucadendron `Silvan Red', Leucospermum `Firewheel', Thryptomene calycina (Lindl.) Stapf., Telopea speciosissima R. Br., and Verticordia grandtiflora Endl. retained a vase life of at least 7 days after 21 days of storage. Leucospermum cordifolium Salisb. ex Knight, Protea neriifoli R. Br., Chamelaucium uncinatum `Alba', C. uncinatum `Purple Pride', Verticordia monadelpha Turcz., Verticordia plumosa (Desf.) Druce, and Verticordia nitens (Lindl.) Schau. suffered a decline in vase life ranging from 31% to 100% after 14 to 21 days of storage. Species of Verticordia and Chamelaucium were particularly susceptible to fungal infection. Anigozanthos pulcherrimus Hook. and the Anigozanthos cultivars Ruby Delight, Bush Harmony, Bush Haze, and Gold Fever all showed a significant reduction in vase life after 14 days of storage compared with unstored controls.

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Andrew J. Macnish, David H. Simons, Daryl C. Joyce, John D. Faragher, and Peter J. Hofman

Postharvest longevity of some cut flowers is shortened by exposure to ethylene gas. Adverse effects of ethylene may be prevented by treatment with 1-methylcyclopropene (1-MCP) gas. Responses of 14 different native Australian cut flowers to 1-MCP and ethylene applied at concentrations of 10 nL·L-1 and 10 μL·L-1, respectively, were examined. Each gas was applied alone for 12 hours at 20 °C and they were also applied in series. Vase lives of Ceratopetalum gummiferum, Chamelaucium uncinatum, Grevillea `Kay Williams' and `Misty Pink', Leptospermum petersonii, Telopea `Shady Lady', and Verticordia nitens were reduced by ethylene treatment. Treatment with 1-MCP generally protected these cut flowers against subsequent exposure to ethylene. The 1-MCP treatment usually did not extend their vase lives in the absence of exogenous ethylene.

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Jong-Suk Lee and Ki-Sun Kim

In spite of its rapid growth in recent years, the floricultural industry in Korea is rather small with respect to total acreage and number of growers engaged, product value, international trade, and production facilities and technics involved. The production status will be introduced with slides. Nevertheless, variable climatic conditions of the temperate zone such as the distinctive 4 seasons favor the prosperous growth of a variety of vegetation throughout the Korean peninsular. Thus, it has been wellknown that many ornamental plants native to Korea have good potentials for horticultural use. The morphological characteristics of a few selected plants will be introduced along with slides. These plants include Aster spp, Iris spp, Gentiana soabra, Chrysanthemum zawadski, Pulsatilla koreana, Cymbidium spp, Calanthe spp, Dendrobium moniliforme, Abeliophyllum distichum, Ardisia spp, Hibiscus syriacus, and many others.