Progress Report to the Saratoga Horticultural Research Endowment August 31, 2009

Transcription

1 Progress Report to the Saratoga Horticultural Research Endowment August 31, 2009 Propagation and Commercial Introduction of ARBORETUM ALL-STARS Recommended Plants for Interior California Landscapes Submitted to Saratoga Horticultural Research Endowment Ellen Zagory Director of Horticulture UC Davis Arboretum University of California, Davis (530) Dave Fujino Executive Director California Center for Urban Horticulture University of California, Davis (530)

2 Zagory and Fujino 2 Introduction Water-conserving plants and landscapes are becoming critical as California has been declared in a state of emergency due to persistent drought. Conventional landscapes use a large proportion of the water supply for most urban and suburban homes. For example, approximately 30 percent of the water used daily by a family of four in the United States is devoted to outdoor uses such as watering lawns and gardens, and landscape irrigation uses more than 7 billion gallons per day nationwide (US EPA, 2007). Much of this water is wasted by inefficient irrigation systems and inappropriate plantings. The UC Davis Arboretum collections and programs focus on sustainable horticulture practices and heat and drought-tolerant plants for our Mediterranean climate. In 2005, we launched the Arboretum All-Stars program, an educational outreach program highlighting tough, reliable, low water-use plants that have been tested in the Arboretum (Cary and Zagory, 2007). It features California native plants as well as tough and adaptable non-natives, and many plants are selected for the program based on their value to birds, beneficial insects and other native pollinators when they are incorporated in landscapes. They are also chosen for their ability to withstand infrequent irrigations based on evapotranspiration needs and have demonstrated the ability to grow, and be attractive, with less water. Goals and Objectives Arboretum plant sales have been unable to fill the demand for plants created by the extremely popular All-Stars program. We have been working to build the system and relationships to establish a permanent, cooperative plant testing and distribution program, so that these resourceconserving plants can be made available to a wider audience. We have developed a five-step approach: 1. Initial selection of species which appear to have the characteristics we seek (good performance in the Arboretum, ornamental qualities, heat and drought tolerance, low water use, dependability, ease of maintenance, wildlife value to insect pollinators, birds and beneficial insects). 2. Initial propagation trials to determine most effective propagation protocols and to produce stock plants and plants for field trialing. 3. Field trials to document plant growth and appearance under a variety of irrigation frequencies. 4. Zone garden trials to determine plant performance under a variety of garden conditions. 5. Refinement of propagation protocols, assessment of adaptability to commercial systems and commercial production and marketing. The Arboretum staff s portion of this work has been propagation trialing the distribution of propagation material to commercial partners for their use. We have repeated propagation trials of the selected species throughout the year, examining and reporting on the effects of different hormone levels as well as timing and quality of cutting material. These same plants are simultaneously included in a separate investigative effort being carried out by UCCE researchers who are testing in field trials at UC Davis and in seven counties in different climate zones throughout California (Reid and Oki, 2008).

3 Zagory and Fujino 3 The overall goal of the Arboretum All-Stars plant distribution program is to promote the use of outstanding Mediterranean climate-adapted ornamental plants that require fewer inputs (water, energy, chemical pesticides and fertilizers) than many common nursery plants. The objectives of this project are to: 1. Conduct propagation trials on ten Arboretum All-Stars species. 2. Evaluate propagation success and develop recommended propagation protocols. 3. Transfer successful plants to our project partners for field trials and testing under commercial production protocols, and eventual distribution to retail nurseries. These goals and objectives clearly and directly align with the mission of the Saratoga Horticultural Research Endowment to support research and educational programs that foster the introduction of new and improved plant materials for California gardens and landscapes. Results and Discussion The Arboretum All-Star Commercial Launch team has carried out a successful 2009 distribution of the first group selected plants through 4 partner wholesale suppliers and 22 retailers. Plants are accompanied by point-of-purchase consumer education materials (plant tags, posters, shelf cards) and resources for green industry professionals (nursery staff, landscape designers, landscape managers, Master Gardeners, educators) in the form of on-line and downloadable images and information. At present we are continuing meeting with commercial partners to increase the number of participating retailers and to expand the variety of plants distributed in future years. In this study we selected ten Arboretum All-Stars species for propagation trials (Attachment 1). Cuttings were taken at six times during the year, or every two months: February, April, June, August, October and December. Three hormone treatments were applied based on information in the Arboretum s propagation database, the condition or hardness of propagation material and information available through the literature. Cutting survival, time to rooting and rooting percentage were recorded. Success or failure of terminal, sub-terminal, soft or semi-hard cutting material was also recorded. We have kept detailed records using our computerized record system to track plant source, supplier of original stock, special plant features, all propagation treatment information and photos of plants. Aesthetic qualities will also be evaluated by Arboretum staff. Currently, all six phases of cuttings for the 10 selected species has been completed. Collecting material, preparation of cuttings, application of hormones, preparation of media and sticking has been done. The first three monthly treatments have also been evaluated at this point, rated and results recorded and potted up. Phase four cuttings are still being rated, with the exception of Callistemon Violaceus, which has not yet formed roots nor have they dropped leaves or showed signs of rot. A few of the more quickly rooting species from Phase five have also been rated at this time. While our data set is not yet complete in order for us to do analysis and a final report, trends in plant response are described below for trial species.

4 Zagory and Fujino 4 Arctostaphylos densiflora Howard McMinn The highest rooting and root quality was in late Fall through to latewinter. Ratings began to decline in February, but were strongest in December. Although cuttings did exceptionally well across the board in both October and December, both tip and subtip cuttings at 5000ppm IBA and subtip cuttings at 8000ppm IBA taken in December had excellent results. Berberis aquifolium Compactum As with Arctostaphylos, the best times of the year was Fall and Winter. More specifically, tip cuttings at 5000 or 8000ppm rooted successfully. In both October and December, cuttings were quick to root, and root masses were so large that transplanted cuttings were potted up directly into 4, rather than the 2 sized pot that cuttings are normally placed in. Unfortunately this plant is slow to restart growth after taking cuttings. Callistemon Violaceus Unfortunately, there have been no strong trends for this plant. The best ratings so far came from tip cuttings treated with 8000ppm IBA in December. If this remains the highest rating after all six phases have been analyzed, it may point to trying higher concentrations of hormone for tip cuttings at that time of the year. Cercis occidentalis There have been no good results over the entire year with this species. Almost every cutting has failed to produce any roots or even callus tissue. It would be interesting to try hedging back a plant in the future to produce new juvenile shoots from which to take cuttings. Epilobium canum ssp. latifolium Everett s Choice The best results were found with cuttings taken in April, when softwood growth had begun to harden a bit. All treatments did very well, and cuttings treated with hormone rooted best using tip cuttings. However, the control showed the opposite reaction whre subtips performed the best. Subtip cuttings not treated with hormone actually had the highest rating, vigorous new growth, and extensive root systems. Perhaps the hormone is having a toxic affect on this relatively herbaceous plant. No cuttings could be taken during December, when the plant is dormant. Also, subtips were unavailable as the plant began to reemerge from dormancy in February. Eriogonum giganteum Although the results for this species were generally poor, the best rooting to date came from tip cuttings in February treated with 2500ppm IBA. Roots were brittle, so cuttings should be started in a media that is firm (like oasis cubes) to minimize root disturbance and hopefully improve transplant success. Lessingia filaginifolia var. californica Silver Carpet In general, tip cuttings clearly rooted better than subtip cuttings. Although all hormone treatments yielded good results, tip cuttings at 2500ppm IBA seemed to do the best compared to other treatments. Unfortunately, all parent plants in the Arboretum collection for the chosen accession number died at the end of winter, so new source plants were chosen in April. The original

5 Zagory and Fujino 5 material was weak and spindly, although it did show significant ability to root. However, the newer more succulent material used in April yielded perfect results from both tip and sub tip cuttings treated with 2500ppm IBA. Ribes malvaceum ( Solstice ) This unusual clone blooms reliably for us from November through January. Interestingly, the best results came from cutting material taken in December, when the plant was in flower. Tip cuttings gave the best roots, and the rooting increased as the hormone concentrations increased. The rest of the year, Ribes malvaceum had little to no rooting for all treatments. Salvia apiana For most of the year, Salvia apiana showed a poor ability to root. April was the only month that had significantly positive results with subtips at 2500ppm IBA. As hormone concentrations increased, subtips continued to perform better than tips, but root ratings decreased overall. At this time of year, the parent plant was beginning to flower, but all cutting material was chosen from shoots that had not yet begun to flower or bud. Salvia clevelandii Aromas The best cuttings came from new succulent material in late winter to mid spring. The newest succulent material tended to do well using both tips and sub tips; higher hormone concentrations gave the best roots. As cutting material began to mature slightly in April, sub tips rooted better than tips. Conclusion We have just completed the last of the six treatments for each of the experimental plants. We will continue to evaluate and rate the rooting response of these last as yet unexamined treatments. We will continue recording all propagation treatment information and track rooting success rates and time to rooting with different cutting types (terminal, subterminal, soft or semihard), different hormone protocols, and different times of year which will be compiled into a final report to the Saratoga Horticultural Endowment. Upon completion and submission of the final report (we anticipate early November) to SHRE, the information will subsequently be made available to nursery partners and through trade magazines and newsletters. Attachment1. Ten species selected for trial Salvia clevelandii Aromas Salvia apiana Ribes malvaceum ( Solstice ) Eriogonum giganteum Lessingia filaginifolia var. californica Silver Carpet Epilobium canum ssp. latifolium Everett s Choice Cercis occidentalis Callistemon Violaceus Berberis aquifolium Compactum Arctostaphylos densiflora Howard McMinn

6 Zagory and Fujino 6 Attachment 2: 100 UC Davis Arboretum All-Stars Selections. Scientific Name Acacia boormanii Acca sellowiana [Synonym- Feijoa sellowiana] Arbutus andrachne Aristolochia californica Aquilegia eximia Arctostaphylos densiflora Howard McMinn Aster 'Purple Dome' Ballota pseudodictamnus Berberis aquifolium Compacta Bergenia crassifolia Bletilla striata Bouteloua gracilis Bulbine frutescens Callistemon Violaceus Calycanthus occidentalis Carex divulsa Carpenteria californica Ceanothus Concha Ceanothus maritimus Valley Violet Ceanothus x pallidus Marie Simon Ceanothus Ray Hartman Cerastium tomentosum Ceratostigma plumbaginoides Cercis occidentalis Cercocarpus betuloides var. blancheae Chionanthus retusus Clytostoma callistegioides Crataegus phaenopyrum Crinodendron patagua Cyclamen hederifolium Cyrtomium falcatum Daphne odora Aureomarginata Dasylirion wheeleri Echeveria Imbricata Epilobium canum Erigeron karvinskianus Erigeron W.R' Eriogonum giganteum Festuca californica Hardenbergia violacea Helleborus argutifolius Helleborus x hybridus Hesperaloe parviflora Heteromeles arbutifolia Heuchera Lillian s Pink Heuchera maxima Heuchera Rosada Hunnemannia fumariifolia Iris Canyon Snow Isomeris arborea Jasminum nudiflorum Kniphofia Christmas Cheer Koelreuteria elegans subsp. formosana Lagerstroemia hybrids and cultivars Lavandula Goodwin Creek Grey Lavandula stoechas Otto Quast Lessingia filaginifolia var. californica Silver Carpet Common Name Snowy River wattle pineapple guava Turkish madrone California pipevine serpentine columbine Vine Hill manzanita purple dome Michaelmas daisy false dittany Compact Oregon grape pigsqueak Chinese ground orchid blue grama grass Cape balsam purple bottlebrush western spice bush Berkeley sedge carpenteria Concha ceanothus violet maritime ceanothus Marie Simon ceanothus Ray Hartman California lilac snow-in-summer dwarf plumbago western redbud island mountain mahogany Chinese fringe tree violet trumpet vine Washington hawthorn Chilean lily-of-the-valley tree ivy leaf cyclamen Japanese holly fern winter daphne desert spoon hens and chicks California fuchsia Santa Barbara daisy Wayne Roderick seaside daisy Saint Catherine s lace California fescue lilac vine Corsican hellebore lenten rose coral yucca toyon, christmas berry, california holly Lillian Henningsen s coralbells island alumroot Rosada coral bells Mexican tulip poppy Canyon snow Pacific iris bladderpod winter jasmine Christmas cheer poker plant Formosan flame tree crape myrtle Goodwin Creek lavender Otto Quast Spanish lavender silver carpet California-aster

7 Zagory and Fujino 7 Leucophyllum frutescens Leucophyllum langmaniae Lynn s Legacy Lonicera standishii Mandevilla laxa Miscanthus sinensis (dwarf varieties) Muhlenbergia dubia Muhlenbergia rigens Neomarica caerulea Nepeta x faassennii Origanum Betty Rollins Osmanthus x fortunei 'San Jose' Penstemon heterophyllus 'Margarita B.O.P.' Philadelphus 'Belle Etoile' Phlomis purpurea Quercus lobata Rhodophiala bifida Ribes aureum Ribes malvaceum Ribes viburnifolium Rosa Gruss an Aachen Rosa Iceberg Rosa Perle d Or Rosa x odoratus Mutabilis Rosmarinus officinalis 'Mozart' Russelia equisetiformis Salvia apiana Salvia clevelandii 'Winnifred Gilman' Salvia greggii and Salvia x jamensis Salvia microphylla Salvia spathacea Saponaria x lempergii 'Max Frei' Sedum palmeri Solidago californica, select form Sollya heterophylla (pink form) Sprekelia formosissima Sternbergia lutea Stipa gigantea Syringa x laciniata Teucrium chamaedrys Nanum Teucrium fruticans Viguiera parishii Woodwardia fimbriata Zephyranthes candida cenizo ( Texas ranger ) Lowrey s everblooming Cimarron rainsage winter honeysuckle Chilean jasmine Japanese silver grass Mexican deergrass deergrass walking iris hybrid catmint dwarf oregano hybrid tea olive Santa Margarita foothill penstemon purple spot mock orange pink phlomis valley oak red Argentine amaryllis golden currant chaparral currant evergreen currant Gruss an Aachen floribunda rose iceberg rose Golden pearl polyantha rose butterfly rose Ed Carman's rosemary coral fountain California white sage Winnifred Gilman Cleveland sage autumn sage mint bush sage hummingbird sage hibrid soapwort Palmer s sedum California goldenrod Australian bluebell creeper Aztec lily yellow autumn crocus Giant feather grass Cut leaf lilac dwarf germander Bush germander desert goldeneye Giant chain fern Argentine rain lily