Vol. 15, No. 1 Winter 1998 PRUNING LANDSCAPE TREES & SHRUBS Tuesday, February 17, from 9 a.m. to 3 p.m. Graham Visitors Center, Washington Park Arboretum (WPA) $35 including lunch, $25 without lunch; pre-registration required INSTRUCTOR: Dr. Ray Maleike, Extension Horticulturist, Washington State University- Puyallup PROGRAM OVERVIEW: This entry level inten- sive program will begin with classroom lec- tures reviewing pruning tools, techniques and timing relative to training, preserving and renovating landscape trees and shrubs. The program will then move out into the Arbore- tum collections for demonstrations and further discussions of pruning techniques for specific plant groups, including rhododen- drons and azaleas, other common deciduous and evergreen shrubs, broad-leafed ever- green and coniferous trees. MANAGING FOR SLOPE STABILITY Thursday, March 5, from 8:30 a.m. to 4 p.m. NHS Hall, UW Center for Urban Horticulture (UW CUH)-Union Bay $60, including lunch; pre-registration required. GEOLOGY & HYDROLOGY REVIEW Derek Booth, UW Professor of Civil Engineer- ing and Geology, and Director of the Center for Urban Water Resources Management, provides an overview of the underlying geologic and hydrologic conditions and processes that lead to soil erosion & slope failure. VEGETATION & SLOPE STABILITY Elliott Menashe, Owner and Consultant, Greenbelt Consulting, will discuss the benefits and limitations of vegetation to slope stability on an intact site and will provide key items to look for when evaluating a site for potential instabil- ity. ENGINEERING SOLUTIONS & SLOPE STABILITY Dale Hemphill, Owner and Consultant, Hemphill Consulting Engineers, will address drainage issues and the engineering aspects of stabilizing a slope with a variety of types of retaining walls. GEOTEXTILES & SLOPE STABILITY Bob Holtz, UW Professor of Civil Engineering, evaluates various types of geotextiles and their contributions to slope stability and erosion control. VEGETATION IN CONJUNCTION WITH ENGINEER- ING SOLUTIONS Elliott Menashe returns to discuss principles for incorporating vegetation with engineering solu- tions. He will recommend vegetation to use for different site exposures, sequential plantings of trees, and methods to stabilize urban ravines. RESEARCH & PROJECT UPDATE Clement Hamilton, Director, UW CUH and Associ- ate Professor of Plant Taxonomy, will provide a brief overview of slope stabilization research and projects emanating from the Center for Urban Horticulture. ProNet Professional Networking Opportunities We are pleased to introduce ProNet, a new for- mat we are introducing into our ProHort program. Designed to enable landscape, arboriculture and urban ecology professionals to interact with their colleagues, discuss current issues, and ex- change information, ProNet was created based on audience assessments, evaluations and focus groups. Each of these free programs will begin with a very short presentation on a specific topic followed by open discussion. Discussions will be allowed to proceed in whatever direction the participants desire, whether that means staying on the focus topic, or diverging into other group or multiple group discussions. This net- working program will also provide attendees the opportunity to give UW faculty and staff feedback on industry needs. ProNet sessions will be held the 2nd Wednesday of each month through the end of this year. They will initially alternate between mid-day and post-work meeting times. ABSTRACT THINKING: Current Resear^^ Abstracts of Interest Compiled by Dave Stockdale, CUH Education Coordina- tor and Aaron Cady, CUH Program Assistant Abstracts reprinted here were selected to represent the broad variety of topics of interest to our readership and to stimulate thinking and debate, and are not intended as endorsements of the research or researchers cited. We suggest you read the complete articles to evaluate the merits of the information provided relative to possible applications to your work situation. All journals cited are available in the Elisabeth C. Miller Library. Soil Compaction on Construction Sites Thomas B. Randrup. Journal of Arboriculture 23(5):1207-210. September, 1997. Soil compaction was estimated on 17 construction sites and bulk densities were measured from the soil surface to depths of 1.0 m, at 0.1 m intervals, using a nuclear moisture/density probe. Soil on construction sites was heavily compacted at depths from 0.3-0. 8 m. Suggestions for a new attitude to soil compaction on construction sites are made. COLD HARDINESS OF LANDSCAPE PLANTS Wednesday, January 14, from 12 to 1:15 p.m. FREE; coffee & cold drinks provided Isaacson Classroom, UW CUH-Union Bay Facilitator: Dr. Linda Chalker-Scott, Associate Professor of Landscape Science and Plant Man- agement, UW CUH NEW PLANTS IN THE ARBORETUM COLLECTIONS Wednesday, February 11, from 5:15 to 6:30 p.m. FREE; coffee & cold drinks provided Isaacson Classroom, UW CUH-Union Bay Facilitator: Randall Hitchin, WPA Registrar/ Collections Manager SEASONAL LANDSCAPE PEST PROBLEMS Wednesday, March 11, from 12 to 1:15 p.m. FREE; coffee & cold drinks provided Isaacson Classroom, UW CUH-Union Bay Facilitator: Mary Robson, WSU/King County Cooperative Extension Agent How To Calculate Areas Eric Liskey. Grounds Maintenance , p. 44. October, 1997. Virtually every designer or maintenance worker must at some time calculate the area of a landscape space. Such skills make calculating the number of bedding plants needed, the volume of mulch to order, or the amount of sod needed easier. This article provides a great review of the formulas for calculating the areas of squares, rectangles, ovals, circles, trapezoids, tri- angles, and even irregular or unusual shapes. An Evaluation of Repetitive Summer Horticultural Oil Sprays on Selected Woody Landscape Plants Fredric Miller. Journal of Environmental Horticulture 15(2):102-108. June, 1997. In order to evaluate the effect of repetitive verdant horticultural oil sprays on plant growth and appearance 32 different species/cultivars of shade trees, ever- greens, and woody shrubs were sprayed three times during the 1994 growing season with 2% SunSpra^^ Ultra-Fine spray oil. Visual phytotoxicity ratings w^B assigned to treated plants and growth affects wer^ measured by measuring leaf area and incremental twig (growth following the last spray application. No phytotoxicity was observed on any of the 32 species/cultivars of woody plants using three repetitive verdant horticultural oil sprays. Collec- tively, repetitive oil sprays did not significantly affect incremental twig growth or leaf area of untreated plants. Results from this study show that repetitive sprays of 2% SunSpray Ultra-Fine spray oil can be used safely on shade trees, evergreens, and deciduous landscape shrubs commonly grown in the upper Midwest. growth was least in the transplant year, followed by 3-6 years of increasing growth rates that met or exceeded growth rates in the nursery. Five of the sites supported growth rates similar to open- grown trees in a semi-natural, park-like setting, while trees growing in an irrigated, fertilized tree lawn had substantially higher growth rates. Our findings suggest that planting specifications can overcome many of the limitations to tree growth imposed by the urban environment, at least during the first 15 years following installation. Using Tree Growth Rates to Evaluate Urban Tree Planting Specifications Barbara A. Neal and Thomas H. Whitlow. Journal of Environmental Horticulture 15(2):115-118. June, 1997. Annual growth was measured from increment cores extracted from 105 willow oaks ( Quercus phellos) growing in seven locations in the metro- politan Washington, D.C. area. Sample sites were selected to represent a range of planting specifications. In general, annual incremental PROHORT BOOKSHELF by Valerie Easton, Horticultural Librarian The Miller Library is open Monday, 9 a.m. to 8 p.m., Tuesdays through Fridays, 9 a.m. to 5 p.m., and Saturday, 9 a.m. to 3 p.m. All the books listed below are available in the library. Contact the library by email at hortlib@u. washington.edu, or visit the library’s new web page at http://weber.u. washington.edu/~hortlib/ for more information. ProHort Seminar Registration Pruning Landscape Trees & Shrubs (with lunch included) $35 Pruning Landscape Trees & Shrubs (without lunch) $25 Managing For Slope Stability $60 Vegetarian meal option where applicable TOTAL: $ Group Rates: 5 or more persons, less 20%. Group registrations must be accompanied by ONE check or purchase order at least 1 week in advance. Portion of fees may cover refreshments and speaker expense. Make checks payable to the University of Washington; receipts available at the door. Mail payment and registration to: UW Center for Urban Horticulture, ProHort, U. of Washington, Box 354115, Seattle, WA, 98195-4115. For further information, call (206) 685-8033. Name/Company Name Address City State Zip Code Daytime Phone Evening Phone To request disability accommodation contact the Office of the ADA Coordinator at least ten days in advance of an event: (206) 543-6450 (voice); (206) 543-6452 (TDD); (206) 685-3885 (FAX), access@u.washington.edu (email). The Random House Book of Perfect Plants, by Roger Phillips and Martyn Rix. New York: Random House, 1996. Pruning: A Practical Guide, by Peter McHoy. New York: Abbeville, 1993. Building Backyard Structures, by Paul Levine, Tom Begnal and Dan Thornton. New York: Sterling Publishing, 1997. The Natural Water Garden: Pools , Ponds , Marshes & Bogs for Backyards Everywhere, by C. Colston Burrell and the Brooklyn Botanic Garden. Brook- lyn, NY: Brooklyn Botanic Garden, 1997. Garden Structures, by Richard Wiles. The RHS Encyclopedia of Practical Gardening. London: Mitchell Beazley, 1992. College of Forest Resources Center for Urban Horticulture University of Washington Box 354115 Seattle, WA 98195-4115 09-9615-122 NONPROFIT ORG. U.S. POSTAGE PAID SEATTLE, WA PERMIT NO. 62 Winter 1998 OTHER EDUCATIONAL OPPORTUNITIES EDMONDS COMMUNITY COLLEGE WINTER COURSES: Introduction to Horticulture; Conifer Identification; Soils & Plant Nutrition; Pruning; Landscape Studies; Horticultural Careers; Green- house Studies; Mixed Border Practicum; Design Presentation; Plant Propagation; Wholesale Nursery Operation; Computer Landscape Graph- ics; Sprinkler Design; Landscape Renovation; Pest Management Principles; Interior Plants; Turf Physiology; Turf Professionalism; Landscape Design I; Bidding & Estimating. Call (425) 640- 1739 for more information. LAKE WASHINGTON TECHNICAL COLLEGE WIN- TER COURSES: Interior Plant Design; Plant Identi- fication II; Landscape Design I; Irrigation Design & Management; Urban Forestry; Pruning & Land- scape Renovation; Soil Amendments & Mulch; Soil Science; Plant Science. Call (425) 739-8100 for more information. SOUTH SEATTLE COMMUNITY COLLEGE WINTER COURSES: Winter Plant ID: Conifers; Landscape Design II; Principles of Horticulture Science I; II; Soils; Pruning; Plant Propagation; Urban Tree Problems; Small Business Management for Horti- culture; Small Engine Repair; Hazardous Trees/ Cabling; Landscape Contracts & Specifications; Landscape Design V; CAD for Landscaping II; Interior Landscaping; Externship; Special Topics. Call (206) 764-5394 for more information. WASHINGTON STATE NURSERY & LANDSCAPE ASSOCIATION WINTER PROGRAMS: WSNLA Con vention, January 8-10, Tacoma; speakers will in- clude John Elsley on “New Plants for Northwest Gardens” and “New Perennials and Selected Roses”, Stephanie Cohen on “Retailing- the Water- loo Way”, Harold Greer on “Rhodies & Azaleas for the Northwest Garden”, plus additional presenta- tions and activities. Call (253) 572-3200 to regis- ter or call WSNLA at (253) 863-4482 for informa- tion on upcoming seminars. JK