Diversity and conservation of Rhododendrons in the threatened areas of northern Buru Island, Maluku Islands of Indonesia
Prima Hutabarat, M.Sc.

This project will search for new species and populations of Rhododendron in the mountainous regions of the Island of Buru, Indonesia. The Buru forests are considered a distinct ecosystem due to remarkable biodiversity, which includes an unusual mix of species from Asia and Australia. Researchers will resurvey locations investigated in the 1960's by Sleumer and in 2015 by Argent, with the main goal of providing data on the conservation status of plants identified in those earlier expeditions such as R. impressopunctatum and R. toxopei. Additional locations that have not been visited since the early 1900s will be surveyed, especially at higher elevations where the terrain is steep and difficult to access.

Brief biography of the Principal Investigator (2023)
Prima Wahyu Kusuma Hutabarat completed his M.Sc. in Biodiversity and Taxonomy of Plants at the University of Edinburgh in 2019. His research interest included plant systematics and conservation, particularly in the Ericaceae and Sapotaceae family. He has been working as a researcher since 2015 in Bogor Botanic Gardens, now continuing his passion at the Research Center for Biosystematics and Evolution of The National Research and Innovation Agency (BRIN) in Indonesia. Prima has implemented research in plant systematic and conservation of some Indonesian native and endemic plant taxa and involved in several botanical expeditions in Indonesia. Prima is a member of the Indonesian Society for Plant Taxonomy (PTTI) and Indonesian Genetic and Biodiversity Community (IGBC). He is also active in IUCN Red List conservation status assessments for Indonesian plants.

Rhododendron survey in northern Aceh, Sumatra: diversity, population, and habitats for conservation.
Wendy Achmmad Mustaqim, Faculty of Engineering, Universitas Samudra

This project will explore Rhododendrons of Northern Sumatra, an area which is rich with unique Vireya species. Researchers will visit two summits in Aceh Province, Bur Ni Telong (2617 m) and Bur Ni Geureudong (2884 m), where rare species were identified almost 100 years ago, to determine what the conditions are like in the habitat now, if the plants are still there, and how many plants of each species might be found. Species of interest include: an undescribed variety of Rhododendron (Sleumer 1960, 1966) allied to R. javanicum that tentatively placed under R. javanicum var. teysmannii, along with R. frey-wysslingii, R. banghamiorum, and R. retusum var. trichophyllum. Surveys will also be conducted on four summits which have never before been investigated for the presence of Rhododendron or any other Ericaceae species: Silih Nara (2000 m), Bur Ni Lintang summit area (1774 m); Bur Ni Kelieten top (2930 m), and an unnamed summit in Bintang Subdistrict (2250 m). Surveys along with seed collections and DNA samples will support conservation of these species, by providing critical information about the condition of natural populations and their native habitats, and by opening up opportunities for ex-situ conservation.

Brief biography of the Principal Investigator (2022)
Wendy Achmmad Mustaqim graduated from Universitas Indonesia in 2014 and completed a master's in Plant Biology (Plant Systematics) at IPB University in 2019. His research areas included systematics of seed plants of SE Asia, with most of them from Indonesia with the main interest in the Ericaceae family. He is now a lecturer in Universitas Samudra, Langsa, Aceh Province. He has implemented research and was involved in the various expedition to many areas in Indonesia, for example, 1) botanical explorations of the Ericaceae and other plant families in Mount Tujuh, Jambi, where he found possible pollination of Rhododendron sessilifolium by butterfly; 2) Ericaceae and other highland plants in Mount Jaya (Freeport-MacMoran mining company; 2018) where he discovered some new species of Gaultheria, one of them already published, and 3) research in Ericaceae and selected plant families in Sulawesi (Yayasan Konservasi Biota Lahan Basah; 2019), and many others. Until now, he has published two new species of Rhododendron from Sulawesi in 2022. He is active in IUCN Red List conservation status assessments for Indonesian plants and a contributor to Taxonomic Expert Network for Ericaceae - World Flora Online.

Biogeographic perspectives on life-history strategies and functional traits of Rhododendron species across elevational gradients of Malesia.
Dr. Melissa Whitman, Independent investigator

Examine whether the variation in traits exhibited by tropical Rhododendron species (section Schistanthe, commonly referred to as Vireya) corresponds with their size of their geographic distribution or elevational range of occurrence. Dr. Whitman’s dissertation work on Rhododendron traits for 169 species from Southeast Asia showed that many tropical Rhododendron species display opportunistic flexibility in habitat types, yet retain a relatively consistent stress-tolerant, slow-growth life-history strategy across the different habitats. One explanation for this could be the evolutionary origins of Rhododendron in cold northern climates, meaning some habitat characteristics of the montane tropics (e.g. freezing events) may represent less of an ecological barrier as compared to taxa with tropical origins. These results reinforce Rhododendron as a unique taxonomic group for testing broader ecological concepts related to species distribution patterns, but additional metrics to account for biogeographic position and species relationships are needed to strengthen the interpretation and broader appeal of this research. Thus, the current project will expand on Dr. Whitman’s Ph.D. dissertation work by adding more complex statistical analyses, including cluster analysis to determine how traits relate to habitat where the plants are found, as well as phylogenetic comparative analysis to account for relatedness between species. Outcomes of the project will include publication in a peer-reviewed open-source scientific journal, making the research freely accessible to researchers worldwide, along with digital archiving of the datasets, to promote future work and international collaboration on Vireya.

Brief biography of the Principal Investigator (2022)
Melissa Whitman earned a PhD in biology from the University of Nebraska-Lincoln with an emphasis in ecology. Her research incorporates concepts from macroecology and ecological modeling to investigate mechanisms that shape global patterns of plant distributions, community assembly, and functional traits along environmental gradients. She is especially interested how stress-tolerant flora will respond to climate change, under scenarios such as increased variability of growing conditions as well as shifting competitive pressures. Taxonomic or ecological groups that she uses as a focal point to address broad ecological questions include Rhododendron, orchids, and flora specific to extreme edaphic conditions such as ultramafic soil or granite outcrops. Dr Whitman is currently an independent researcher, engaged in writing and research collaborations with fellow scientists and plant enthusiasts.

Rhododendron photosynthetic plasticity in response to high pH stress
Dr. Gerardo H. Nunez
Horticultural Sciences Department. University of Florida

Gardeners, researchers, breeders, and nurserymen know that rhododendrons suffer in high pH soils. This project aims to answer why this happens. It is well know that high soil pH causes physiological stress in acid-loving plants, leading to reduced growth rate. But, exactly how high pH negatively impacts physiology is not well-known for Rhododendron. This project will test three alternative hypotheses to explain reduced growth in Rhododendron at high pH, 1) increased root death, which reduces water uptake and leaf water use, 2) nutrient deficiencies that damage or prevent repair of the photosynthetic apparatus, and 3) alternatively there may be physiological adjustments that help maintain photosynthetic rates near normal levels despite stressful pH conditions. The project will use rhizoboxes to track root growth for the cultivar “Golden Torch” exposed to different pH conditions, along with using infra-red gas analyzers to measure leaf-level water use and carbon uptake, fluorimetry to quantify photosynthetic efficiency, along with leaf nutrient and pigment contents.

Assessing reproductive and biochemical traits of Rhododendrons along the elevation gradient in the Eastern Himalaya
Dr. Shweta Basnett
Ashoka Trust for Research in Ecology and the Environment, Bangalore, India

This project seeks to understand how floral traits of Rhododendron species respond to a change in temperature across elevation, and how this in turn impacts the floral resources that pollinators depend on to survive. The study will take place at high elevation sites between 2,000-4,500m (6,500-14,700 ft) in the Kyongnosla Alpine Sanctuary, a global biodiversity hotspot for Rhododendron located in the Eastern part of the Sikkim Himalaya. Traits related to pollinator preference, including flower size, shape and color patterns, along with nectar quality and production rates, will be measured for 30 Rhododendron species. Floral traits will also be used to infer which pollinators visit each species, and which species share pollinators, based on previously published studies of pollinator trait preferences. The work will provide insight into the complex relationships between plants and their pollinators, and how these relationships could be altered by a change in climate. This will be the first study in the Himalayan region to investigate such a wide variety of floral traits across many species at a large geographical scale.

Landscape Adaptability of Rhododendron Species in Northeast Ohio
Connor Ryan
Holden Forests & Gardens, Ohio, USA

This project will evaluate the performance and long-term persistence for a variety of field-grown Rhododendron species, with an eye toward generating recommendations for home gardeners within the Northeast Ohio region, identifying potential breeding targets for new hybrids, and informing selection of species for ex-situ conservation and public display gardens at Holden Forests & Gardens. Plants will be evaluated for cold hardiness, sun tolerance, and pest/disease resistance. Published data on species hardiness from the Species Study Group of the Massachusetts Chapter of the ARS will be used to identify initial trial species, with an understanding that: 1) some species are more cold-hardy than expected based on their native distributions, 2) within a given hardiness zone the nuances of local-scale weather patterns and microclimates within a garden can substantially modify the growing conditions experienced by plants, and 3) long-term evaluation is needed to account for year-to-year variation in climate conditions. Ultimately this 5-year project will result in a modern reference of Rhododendron species suitable for gardens in the region, expanding the landscape palate and conservation opportunities for the midwestern United States.

What's in a species? Investigating morphological, physiological and genetic differences between closely related Southern Azalea species

Dr. Vanessa Koelling
Auburn University at Montgomery, AL

This project will explore differences between two closely related Southern Azalea species, R. cumberlandense and R. prunifolium. The study will incorporate data from plants growing at the Davis Arboretum at Auburn and at other field locations in Alabama and Georgia to characterize variation across species and growth conditions. Morphological and physiological traits related to temperature tolerance will be investigated, combined with next-generation DNA sequencing to identify species-specific genetic markers. This work is expected to advance our understanding of the divergence between these species, and to provide insight into the roles of climate and other selective forces in facilitating the speciation of Azaleas.

Development of High-Throughput Phenotyping Tools for Key Leaf Traits in Rhododendron

Dr. Chase M. Mason
University of Central Florida, Orlando, FL

This project will develop rapid screening techniques for leaf nutrient and secondary metabolite concentrations, which play important roles in plant growth and stress resistance. Using 43 species and subspecies of plants growing at Arnold Arboretum, in-depth measurements will be made by means of gas chromatography, mass spectrometry and capillary electrophoresis, and these data will be employed to calibrate a rapid assessment technique using hyperspectral reflectance, which involves measuring the intensity of light intensity at many wavelengths garnered from digital images. Ultimately, this work is expected set the stage for screening large numbers of species and cultivars in a horticultural context (i.e. identify tolerance of stresses like high temperatures, drought, soil pH or pathogens) and for evolutionary analysis investigating the distribution of traits across species and populations of genus Rhododendron.

Alternative controls to reduce azalea lace bug feeding on rhododendrons

Dr. Jana C. Lee
USDA ARS Horticultural Crops Research Unit
Corvallis, OR

This research proposal seeks to control lace bug on rhododendron using two approaches. One approach is to use lacewing larvae which are natural predators of lace bug. Studies will use volatile lures to attract lace bug and spiny surfaces to induce the insects to lay eggs. Experiments will compare two volatile lures, methyl salicylate and acetophenone, and the effect on spiny surfaces. A second approach to lace bug control is to use silicon supplements to reduce the damage inflicted by lace bug, either by strengthening the plant tissues or by attracting predators such as lacewing larvae.

Screening the Physiological Characterization of Lime-induced Iron Deficiency Chlorosis (IDC) Tolerance in Rhododendron Genotypes

Dr. Johan Van Huylenbroeck
Flanders Research Institute for Agriculture, Fisheries and Food (ILVO)
Plant Sciences Unit – Applied Genetics and Breeding
Melle Belgium

This proposed research is to develop a screening system for lime-induced Iron Deficiency Chlorosis (IDC) tolerant rhododendrons and to physiologically characterize the mechanism for this tolerance. The studies will specifically include INKARHO™ rhododendrons recently developed to have increased tolerance of soils with high pH.

The role of the microbiome in disease resistance to Phytophthora pathogens in Rhododendrons: a mechanistic experiment across phylogeny

Dr. Jean H. Burns
Department of Biology, Case Western Reserve University
Cleveland, OH

The cultivation of Rhododendrons is sometimes limited by pathogens, including the very damaging root rot pathogen, Phytophthora cinnamomi. Research will use a greenhouse inoculation experiment to quantify pathogen susceptibility across 21 different Rhododendron species, whose taxonomy includes Pentanthera, Ponticum, Rhododendron, and Tsutsusi. The goal is to try to determine whether and to what degree the soil root zone microbiome mediates disease resistance.

Back to the Future: Field Evaluations of Rhododendron Rootstocks for Lime Tolerance

Dr. Stephen Krebs
David G. Leach Research Station, The Holden Arboretum
Kirkland, OH

This research will test the higher pH tolerance claims of a proprietary German rhododendron rootstock, INKARHO®, in a field trial where pH is manipulated from a 4.5 to 7.5. Rhododendrons are popular plants, but difficult to grow and prone to failure in some home landscapes partly due to soil conditions. The use of vigorous and adaptable rootstocks could solve many of the soil-related cultural problems confronting rhododendrons and greatly increase growing success generally and into more regions of the US. Specific cultivars including many classic Ironclads will be grown with and without INKARHO rootstock and plant health evaluated for chlorosis by laboratory chlorophyll analysis.

Leaf hydraulic conductance of deciduous, evergreen and semi-evergreen
Rhododendrons:  Diverse solutions to the problems presented by evaporative demand

Juliana S. Medeiros
Scientist, The Holden Arboretum, Kirkland, OH

Leaf hydraulic conductance, or the capacity of the leaf to replace water lost through stomata via transpiration, is one of the most important physiological components of plant tolerance to heat and drought. The project objective is to analyze leaf hydraulic conductance in 17 different species in the genus Rhododendron.

Developing an in-vitro selection method for Rhododendron alkalinity tolerance using the cultivars 'Inkarho' and 'Haaga'.

Dr. Stan Hokanson
University of Minnesota, St. Paul, MN

Soil pH has a large effect on the types of plants that can be grown in a given soil. The alkalinity (pH >7) or acidity (pH <7) of a soil is a major factor in the solubility for vital nutrients that plants use to maintain functions essential to proper growth and development. Through plant breeding, 'Inkarho' rhododendrons have been found to exhibit a tolerance to alkaline conditions. This cultivar provides a unique opportunity to gain an understanding of the physiological mechanisms supporting elevated pH tolerance. In using a rhododendron cultivar that is known to be more tolerant of alkalinity and comparing it with a known intolerant variety, mechanisms for intrageneric (within the genus Rhododendron) variation can hopefully be documented and a precedent established for the future selection of tolerant cultivars. This in-vitro (in a laboratory vessel or other controlled environment) research model will test plants in tissue culture using pH micro-electrodes with subsequent mass spectrometer analysis of media and root tissues. Existence of similar intrageneric variation can then be sought out in other landscape plants and horticultural crops to expand growing ranges and improve plant performance across a large geographic area.

Rhododendron diversity and leaf functional traits across elevation gradients in tropical, subtropical, and temperate regions of SE Asia.

Melissa Whitman
University of Nebraska-Lincoln
School of Biological Sciences, Lincoln, NB

This multi-year project addresses Rhododendrons diversity, and leaf functional traits, across elevation gradients for tropical, subtropical, and temperate regions of SE Asia. Rhododendron with epidermal scales, from Schistanthe (Vireya), Rhododendron, and Pogonathum, will be the focus of this study. Distribution range per species will be estimated using georeferenced herbarium records and information from botanical collections. Functional traits (specific leaf area, % nitrogen, % lignin, scale density) for 150 rhododendron species will be quantified using leaf samples collected from botanical gardens. Preference will be made towards plants grown from wild collected cuttings, and species from resolved polygenetic trees to account for evolutionary history. Data on geographical range, and functional traits, will then be integrated to test whether or not species at lower elevations, or within tropical regions, have more defenses against herbivory than species at higher elevations, or within temperate regions. Practical application of this project includes mapping of Rhododendron diversity for international conservation efforts, as well as estimates of climatic range size, and possible resistance herbivory. Results can then be used to inform selection of species for horticultural use.

Determining the Ploidy of Rhododendron Hybrids and Species Using Flow Cytometry

Sally and John Perkins
Salem, NH

João Loureiro
Department of Life Sciences
University of Coimbra, Coimbra, Portugal

Project objective is to use flow cytometry to identify the ploidy of: 1)  named ploidy elepidote hybrids suspected of being polyploids, 2)  lepidote species concentrating on subsections Cinnabarinum, Heliolepida, Ledum, Lapponica, Maddenia, Tephropepla, and Triflora, 3)  Vireya species concentrating on alpine species and species closely related to laetum and macgregoriae, and 4)  wild populations of subsection Ledum concentrating on mixed populations including x columbianum, glandulosum and groenlandicum.

Microsporogenisis in Rhododendrons: The development of pollen and tapetal cells in relation to periods of low temperature.

Miroslavov Evgeny Komarov
Botanical Institute of Russian Academy of Sciences, Petersburg, Russia

Developing rhododendron hybrids that are heat tolerant as well as disease and insect resistant
primarily using R. hyperythrum as a parent.

Stan Southland
Chapel Hill, NC

Cellular Mechanism of Thermonasty in Rhododendron: Are Membrane Water Channel Proteins (aquaporins) Involved?

Dr. Rajeev Arora
Department of Horticulture, Iowa State University, Ames, IA

One of the goals of this investigation is to gain fundamental insight into the mechanism of cold tolerance in rhododendrons. Thermonasty is the term applied to the leaf drooping and curling phenomenon observed in many, but not all, evergreen rhododendrons. This research will study the cellular mechanisms of thermonasty as water moves across leaf cell membranes which then control leaf movement. It has been proposed that water movement across membranes is likely regulated by water channel proteins called aquaporins. This study will attempt to isolate the genes associated with seasonal cold hardening. A specific objective will be to investigate whether there are changes in gene expression, in a predicted pattern, with temperature- induced leaf curling and uncurling. The two species to be studied, R. catawbiense and R. ponticum, have different behavior with regard to leaf curling in winter.

Functional Significance of Leaf Idioblasts in Vireya Leaves to Water Relations and Photosynthesis.

Dr. Erik Nilsen
Biology Department, Virginia Tech, Blacksburg, VA

The overall goal of this research in Vireya rhododendrons is to learn the functional significance of leaf attributes to improve understanding of Vireya ecology and thereby promote the conservation of Vireya diversity. Specifically, the research will focus on the functional significance of idioblasts to leaf water relations and photosynthesis. Idioblasts are very large cells found to be present in the leaves of all Vireya species but not other rhododendrons. Research with other plant groups suggests that idioblasts may be important for water balance, photosynthesis, temperature balance, chemical storage, oxalate crystal synthesis, and defense against herbivores. This research will focus on water balance and photosynthesis.

Molecular Studies of Rhododendron subgenus Vireya: Implications for International Programs in Conservation Collection
Management and Plant Development.

Dr. Susan E. Gardiner/Davis
The New Zealand Institute for Plant and Food Research
Palmerston North, New Zealand

The researchers will use both molecular and conventional taxonomic methods to investigate the diversity of Rhododendron subgenus Vireya (vireyas) in New Zealand and the USA then examine the diversity in relation to conservation, cultivation and plant development. This project will take two years to complete. The first phase is a survey to build a database and literature review to support taxonomic and molecular research. The second phase will be to use molecular markers, specifically DNA, to examine the broader range of vireyas in the Rhododendron Species Botanical Garden as well as in New Zealand with the goal of determining the value of conserving vireyas that may be endangered of being lost in the wild.

Creating New Hybrid Rhododendrons for Improved Fragrance in Yellows, Oranges and Purples, Handsome Foliage and Heat Tolerance.

Kristi O'Donnell
Director Meerkerk Rhododendron Gardens Greenbank, WA

Meerkerk Rhododendron Gardens, founded in 1961, has been involved with hybridizing rhododendrons since the 1970's. The projects objective is to create fragrant hybrid rhododendrons with uniquely pigmented flowers and handsome foliage with a tolerance of drier summer soils. On Whidbey Island, because it is in a rain-shadow, summers are drier than surrounding regions. Some crosses will use R. macrophyllum in the hopes that hybrids will be more tolerant of drier conditions. The public is also often unaware that many rhododendrons are fragrant. If the goal is obtained of developing hybrids with fragrance in colors such as yellow, orange or deep purple, good looking form and foliage as well as tolerance of drier soils, then this would help the broader promotion of rhododendrons.

Nonanoic Acid and Trichoderma Isolates for Management
of Botrytus Petal Blight and Phytophthora Dieback

Thomas J. Gianfagna
Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ

It has been discovered that some microorganisms have antibiotic control of fungal pathogens. The research involves isolation of specific compounds from specific kinds of bacteria and testing their effect on two kinds of fungal disease under controlled greenhouse conditions. The anticipated benefits to rhododendron growers are a potential biofungicide that will be cheaper than currently registered conventional fungicides and which is environmentally friendly.

Genome Sizes in Rhododendron ssp.

Leen Leus
Institute of Agricultural and Fisheries Research, Melle, Belgium

The numbers of chromosomes, also known as ploidy levels, are of interest for plant breeders as polyploidy (extra sets of chromosomes) can influence characteristics of growth vigor or in the case of ornamentals, the ornamental value. The analysis of the DNA content can give more information than just the ploidy level. Although a lot of information is available about the number of chromosomes among certain genotypes of rhododendrons, little information is available about the genome size. Genome size is important from a phylogenetic point of view and also important for plant breeding.

Improving Fertilizer and Water Use Efficiency of Container-Grown Rhododendron

Carolyn F. Scagel
USDA-ARS-Horticulture Crops Laboratory, Corvallis, OR

The objective of this multi-year study is to characterize the seasonal dynamics of nitrogen uptake and internal cycling in evergreen and deciduous rhododendron cultivars. The effects of liquid and controlled release fertilizer on plant growth and nitrogen uptake will be compared and the influence of nitrogen on water use and photosynthetic performance will be assessed.

It is hypothesized that excess nitrogen during nursery production decreases the efficiency of water use and the quality of container grown rhododendrons. This has important environmental as well as economic implications. Avoiding excess fertilizer run-off and increasing fertilizer efficiency is a hopeful expected outcome this research.

Breeding Polyploid Rhododendrons and Azaleas

Thomas Ranney
Department of Horticultural Science, North Carolina State University, Fletcher, NC

Polyploids are organisms that have more than two complete sets of chromosomes. Polyploidy will be induced chemically in rhododendrons resulting in triploid and tetraploid sets of chromosomes. The objective is to determine ploidy level and genome size of a diverse range of species, hybrids and cultivars of rhododendrons using a combination of flow cytometry and light microscopy.

Mechanisms for Winter Photoprotection in Rhododendron subsection pontica: a physio-genetic analysis

Dr. Stephen Krebs
The Holden Arboretum, Kirtland, OH

Temperature-leaf leaf movement, termed thermonasty, possibly functions in evergreen Rhododendron species by reducing oxidative stress in leaves caused by winter sunlight.  Thermonasty varies among Rhododendron species and appears to be positively correlated with cold hardiness.  This proposal explores that relationship and asks whether thermonasty is a necessary condition for winter hardiness.

The hybridization of R. catawbiense (exhibits thermonasty) and R. ponticum (does not exhibit thermonsaty but has phototolerance to winter sun) in the Waterer hybrids created the "ironclad rhododendrons" resulting in greatsuccess in growing under a wide range of conditions.  This research proposes to test the hypothesis that more than just thermonasty, possibly a biochemical response, is responsible for cold hardiness and that there may be an additive effect by relying on different mechanisms for photoprotection from winter sun.

Mapping the Dstribution of Rhododendron arboreum ssp. nilagiricum (Zenker) Taag,
Using Ecological Niche Modeling and Develop Conservation Plan

Amarnath Giriraj
Department of Ecology
French Institute of Pondicherry, Pondicherry, India

Rhododendron is an important genus occurring in the high altitudes of the Himalayan region, having ecological significance and economic importance in addition to its graceful flowers.  India records 72 Rhododendron species, 20 subspecies and 19 varieties.

Precise information on a species including distribution and ecology is important in developing management and conservation strategies.  The project objectives are to prepare distribution maps of the Western Ghats region for Rhododendron arboreum ssp. nilagiricum, identify ecological limiting factors for distribution, analyze management practices in locations not under conservation, assess the threat status for this species, and identify possible areas for reintroduction or range extension.

The significance of the research will be to prepare a conservation action plan for the management of the habitat and Rhododendron arboreum ssp. nilagiricum species for sustainable biodiversity conservation.

Rhododendron Database Project – Hybrid Phase

Dr. Forrest E. Bump, Jeffery M. Chase and Carol A. McCarthy
Forest Grove, OR

The goal of this project is to develop a not-for-profit electronic Internet and computer-searchable Rhododendron Database containing multiple characteristics of rhododendron species and hybrids.  The database resource will be accessible to rhododendron experts, hybridizers, nursery professionals, American Rhododendron Society members and the general public.  The database will be utilized to identify, contrast, and compare the characteristics of various rhododendrons.  Each plant record will have 40-50 different identification features and plant characteristics.  The database will provide a comprehensive analytical tool for those studying and developing rhododendrons.

Identifying Taliense Rhododendrons Using Leaf Waxes

Professor David W. H. Rankin
University of Edinburgh
Edinburgh, UK

The subsection Taliensia includes several species such as R. aganniphum, R. alutaceum, R. phaeochrysum and R. roxieanum, which are highly prized for their flowers and foliage.  Taxonomy is difficult due to natural hybrid swarms and one of the primary goals of this research is to use the chemistry of leaf waxes as markers for species characterization and identification.  A study of leaf waxes is much less expensive than DNA analysis.  The significance of the work will be to see if species in the Taliensia subsection can be characterized and then confirm if species can be differentiated from hybrids.  This will help growers and botanists with implications for both conservation and horticulture.

Development of a USDA Zone 4A Rhododendron Cold Hardiness Trial/Display Garden

Dr. Stan Hokanson
Department of Horticultural Science
University of Minnesota, St. Paul, MN

The primary goals will be to develop a wider range of flower colors and more reliably bud-hardy rhododendrons for Zone 3/4 landscapes.  The proposed trial/display garden will be on the grounds of the Minnesota Landscape Arboretum in Chanhassen, Minnesota and will be open to the public.  For many visitors, viewing the proposed display garden would be a rare encounter with evergreen rhododendrons.  A local architect has donated the landscape design and funds will be used to properly prepare planting areas.

Collection of Winter Hardy Rhododendrons at the Central Siberian Botanical Garden in Novosibirsk, Russia

Elena Chernykh and Dr. Tatyana Novikova
Central Siberian Botanical Garden, Novosibirsk, Russia

The goal is to find winter hardy genotypes of rhododendron species that will grow well under the conditions of Novosibirsk.  Russian botanists recognize 12-15 species native to Western and Eastern Siberia and the Russian Far East Region.  Species of greatest interest are R. ledebourii, R. dahuricum, R. mucronulatum and R. sichotense.  These species exhibit tremendous variations in size and flower color.  Micropropagation techniques will be applied to selected clones and seed will be sent to the ARS.

Ecology of Vireya Species in their Natural Habitat

Dr. Erik T. Nilsen
Biology Department, Virginia Tech

A new giant cell type with unusual cellular morphology has been identified as being unique to vireya rhododendrons.  The goal of this study was to validate this observation in natural populations of vireyas in New Guinea, take tissue samples for later DNA and microscopic laboratory analysis, and do field experimentation measuring photosynthesis in response to various light and carbon dioxide conditions.  Outcomes will provide a greater understanding of the ecology of vireyas and the function of the newly discovered cell type.

An Evaluation of Powdery Mildew Disease on Deciduous Azaleas Cultivars

Dr. Stan Hokanson and Dr. Stephen L. Krebs
Department of Horticultural Science, University of Minnesota

The researchers will evaluate over a two-year period, 50 deciduous azalea cultivars and species in two separate locations (Minnesota and Ohio) for resistance to powdery mildew.  A second phase includes a survey of additional numbers of cultivars and species in eastern North American public gardens, significantly broadening the study.  While plant pathology is not the primary focus, attention will be given to identifying the fungal species involved.  An expected outcome is not only a "good doer list" of species and cultivars, but ratings will assist breeders for further plant introductions.

Cold Acclimation and Freezing Tolerance in Rhododendron maximum

Dr. Gary C. Harris
 Biology Dept., Wellesley College

Techniques of protein extraction and analysis by two-dimensional gel electrophoresis will be refined and key leaf and thylakoid membrane proteins will be identified during a yearly developmental cycle.  A through understanding of the molecular aspects of cold acclimation and freeze tolerance could be of great significance in efforts to improve varieties and extend the growth range of rhododendron species into colder climatic zones.

Collection of Rhododendron sect. Vireya in Sulawesi, Indonesia for Studies Into Their Evolutionary Relationships and Biogeography

Dr. Lyndley A. Craven
Principal Research Scientist
Australian National Herbarium, CSIRO Plant Industry

The objective of the project is to obtain herbarium and live material, for both DNA and morphological studies, of a group of species that is not well known.  Material for propagation will be collected when possible.  Cutting material will be sent to the Rhododendron Species Foundation after establishment in Australia.  Wild-collected seed will be sent to the Vireya seed exchange.

2000

Locating and Propagating Superior Typical and Atypical Species
Selections of East Coast Deciduous Azaleas in the Luteum Subseries

Clarence Towe, ARS Member

Growth of Rhododendrons on Calcareous Soils

Prof. David W. H. Rankin
Dept. of Chemistry, University of Edinburgh

Western North American Rhododendron Species Project

Henry R. Helm, ARS Member

An Exploration and Study of White Rock Mountain, West Virginia, for Unusual Forms of Rhododendron Species

Parker Lewis Little., ARS Member

Mapping Genes that Confer Freeze-Tolerance in Rhododendrons

Dr. Rajeev Arora, West Virginia University, and Dr. Stephen L. Krebs Research Station of Holden Arboretum, Madison, OH

A Compilation of a Hybrid Rhododendron Computer Database with Complete Parentage Diagrams

Homer Salley, ARS Member

Western North American Rhododendron Species Project

Henry R. Helm, ARS Member

1996

The Physiological and Genetic Characterization of Rhododendron
Populations Segregating for Cold-Hardiness

Dr. Rajeev Arora
West Virginia University, Morgantown, W. VA

1994

Subirrigation of Rhododendron Softwood Cuttings: A Method of Rooting Without Mist or Fog

A. Aiello, W. Graves, and J. Iles
Iowa State University

Powdery Mildew of Rhododendron - A Taxonomic Survey

J. Pscheidt
Oregon State University

1993

Genetic Analysis of Isozyme Loci in Rhododendron

S. L. Krebs and D. G. Leach
David G. Leach Research Station of the Holden Arboretum

New Black Vine Weevil Management Strategies and Educational Programs

R. S. Cowles
University of California, Riverside, CA

A Histological Evaluation of Gall Formation Associated with Tissue Proliferation in Affected Rhododendron Cultivars

B. K. Maynard
University of Rhode Island, Kingston, RI

A Database of Rhododendron and Azalea Research with Related Scholarly Data, Volume Two

Dr. Homer E. Salley, Grand Rapids, OH

Evaluation of Anagrus sp. Egg Parasitoids as Biological Control Agents for the Azalea Lace Bug

Dr. S. Kristine Braman, Karl E. Espelie, and Julie A. Wise
University of Georgia, Griffin, GA

1991

Evaluation of Horticultural Oils and Other Products for Azalea Lace Bug Management

Dr. S. Kristine Braman
University of Georgia

Minimum Calcium Requirement for Container Grown Rhododendron

Dr. David R. Hershey
University of Maryland

A Database of Rhododendron and Azalea Research with Related Scholarly Data

Mr. Homer Salley, Grand Rapids, Ohio

Journals in Libraries

Great Lakes Chapter, ARS, Dana Lewis
Research Representative, Ann Arbor, Michigan

Identification and Control of a New Azalea Flower Blight Disease

Dr. Gordon Holcomb
Louisiana Agricultural Experiment Station, Baton Rouge, Louisiana

Determine the Effect of Growth Retardants and Fertility Control on Flowering and Growth of Young Rhododendrons

Willard D. Witte, University of Tennessee, Knoxville, Tennessee