The research committee is interested in the
following issues of both practical and theoretical value to rhododendron
Physiological and genetic factors affecting
tolerance of rhododendrons to heat, cold, drought, insects, and diseases.
Why are some rhododendrons more susceptible than others? How do we use
this information to breed more tolerant rhododendrons?
What can be done to counteract the intolerance of
current rhododendrons to various adverse factors, such as powdery mildew and
petal blight? Are there chemical or biological control agents that are
effective against these pathogens?
Plant exploration in the U.S., the dissemination of
new plant germplasm found, and the maintenance of such new germplasm.
Polyploidy and aneuploidy in hybrid rhododendrons;
chromosome numbers (different from 2N=26) in Rhododendron
More generally, members of the society have
identified a broader range of subjects as appropriate for ARS-funded research.
- Studies on the biosystematics of native
American Rhododendron species, including the collection of superior clones and
populations for distribution to the members through the Seed and Pollen
- Support for the introduction of foreign
- Translation of key botanical research
publications on Rhododendron published in German, Japanese, etc.
- Methods for screening and breeding for cold
- Breeding for heat tolerance.
- Breeding for resistance to root weevils.
- Breeding for improved fragrance.
- Develop charts for interspecific
- Techniques for improving the success of wide
crosses and overcoming incompatibility systems.
- Improved methods for crossing deciduous with
- Computer systems to handle all aspects of
record-keeping for breeding programs, with wide applicability to a large
number of amateur breeders.
- Examination of pruning effects across various
- Develop a schedule and appropriate techniques
to establish container-grown plants in soil.
- Study the effects of dead heading (removal of
spent blossoms and developing seed pods) on succeeding year's flowering.
- Studies on growing rhododendrons and azaleas
under competitive trees, such as pines, maples, dogwoods, tulip poplars,
Douglas fir and madrona.
- Pruning and other cultural methods for the
rejuvenation of plants that are too large or rangy.
- Low-cost growing media and weed control
methods for container plants.
- Cultural methods to set flower buds on very
- Methods to protect plants from damage by
extreme environmental conditions, such as hot, dry weather, extreme cold, etc.
- Development of a sleeve to enclose stems to
avert bark splitting.
Cytological and Genetical Research:
- Studies on the inheritance of flower color and
relationships between flower color and environmental adaptation.
- Determination of chromosome numbers in species
and cultivars, especially for deciduous azalea cultivars.
- Studies on the inheritance of fragrance,
indumentum, and truss size.
- Production of haploids and/or polyploids.
- Tests of tubulin antagonists and antimitotic
chemicals for their ability to induce polyploidization.
- Development of methods for in vitro
selection of tissue cultures for resistance to diseases, pests, and extreme
- Evaluation of species and hybrids for flower
color pigments, especially in sections of the genus not studied to date.
- Develop safe, but effective fertilization
schedules for both container-grown and field-grown plants.
- Study the role of calcium on plant vigor.
- Study the role of phosphorus in bud set and
the effects of high phosphorus on chlorosis, and relationship to the pH of the
- Research on the influence of nitrogen on bud
- Study the effects of fall fertilization.
- Study the effects of alfalfa leaf meal and
other fertilizer supplements on growth.
- Study the role of soluble salts in soil or
artificial media in relation to the predisposition of plants to diseases and
Pest Control Research:
- Develop reliable tests to screen seedlings for
resistance to diseases such as root rot and to other pests.
- Control of Phytophthora dieback.
- Biological control of root weevils and borers,
including the use of predaceous nematodes and insects.
- Use of terpenes and related compounds to repel
- Methods for the long-term control of petal
- Control of galls on azaleas.
- Studies on the cause, nature, and control of
- Identify cultivars sensitive to Cygon.
- Control of Botryosphaeria dieback.
- Control of powdery mildew, especially in
- Studies on the synergistic effects of
anti-transpirants on pesticides.
- Research on the effect of red spider mite and
other debilitating pests or conditions on susceptibility to other diseases and
- Protection from feeding by rabbits, mice,
moles, deer, etc.
- Control of Armillaria mellea.
- Chemical induction of hardiness and the
practical applications of hardiness induction.
- Cultural manipulations to improve fall
- Prevention of fall flowering.
- Physiological factors affecting bud set.
- Determination of factors affecting fall
hardening, mid-winter hardiness, and dehardening.
- Determination of the physiological differences
between easy-to-root and hard-to-root cultivars.
- Correlation of leaf analysis with soil tests.
- Interaction of fertility levels and light
intensity on plant performance.
- Techniques to break dormancy, especially in
- Physiological factors controlling root growth
and practical applications in promoting extensive root growth.
- Physiological factors affecting disease and
pest resistance and possible application in the area of systemic immunization.
- Studies on the effect of chlorinated and/or
"hard" water on growth and plant health.
- Research on dwarfing rootstocks.
- General development of improved propagation
- Research on seed dormancy in wild species, and
techniques to overcome seed dormancy.
- Development of optimal methods for seed
handling and storage.
- Home propagation of hard-to-root cultivars.
- Studies on cutting propagation (including the
effects of sugars, willow extract, growth regulators, soaking, and cutting
- Effects of the temperature of the rooting
medium on rooting success.
- Bulletins, slide presentations, and video
tapes demonstrating propagation methods.
- Innovative methods for the control of
bacterial and fungal contamination in Rhododendron tissue cultures.
- Research on basal callusing and other
undesired variants generated by tissue culture propagation.
Review Papers and Popular Publications:
- Develop outlines of pest control methods and
fertilizer applications for the average gardener.
- Develop small, easy-to-read, "what to do"
booklets on plant problems.
- Prepare illustrated manuscripts on all aspects
of the garden culture of rhododendrons and azaleas for particular sets of
- Develop plans for simple, but effective,
structures for indoor growing of plants and seedlings.
- Reprint out-of-print bulletins of interest to
- Develop slide presentations and/or video tapes
of general interest to society membership.
Other Areas of Research:
- The Research Committee will consider original
research proposals in areas other than those listed above, provided that the
findings are directly applicable and of value to the membership of the
Society. However, the problems listed are those that were considered
some time ago to be of highest priority and interest to the membership.
For additional information contact the Chairman
of the ARS Research Committee: