David G. Leach Research Station

The Holden Arboretum’s David G. Leach Research Station is a satellite facility maintained for horticultural research on a 30-acre property, 40 minutes east of Holden’s Kirtland campus. The land was a gift to Holden from David Leach, PhD, who developed it as a rhododendron breeding and evaluation garden. Normally closed to the general public, the research staff hosts a series of open houses each spring when the gardens are in bloom. Times and dates are published in the the spring class schedule.

Leach was an eminent American horticulturist who became a world authority on genus Rhododendron, and is renown for his development and introduction of hardy (zone 5) hybrid rhododendrons for the gardening public. The Leach Station is staffed and equipped to support extensive and diverse display gardens, in addition to large breeding populations and research plots.

Under the direction of plant breeder and geneticist Stephen Krebs, PhD, the station maintains its commitment to developing superior rhododendrons for continental climates (i.e. cold winters and hot summers). The traditional breeding program is now complemented by a vigorous research component focused on adaptations of rhododendrons to biotic and abiotic stresses, such as winter freezing injury to leaves and buds, summertime ‘bleaching’ of leaves (photoinhibition), and diseases caused by fungal pathogens (Phytophthora root rot and powdery mildew). The basic questions being addressed are:

• How much natural variation exists among Rhododendron species for tolerance to a particular stress?

• What are the genetic and physiological determinants of this tolerance?

• Can stress tolerance be transferred via conventional or modern techniques to a new generation of hybrids that have improved landscape performance under stressful conditions?

• How is expression of these traits influenced by other key features of woody plant biology, such as juvenility and dormancy?

Research on these questions is being conducted on- and off-site, frequently in collaboration with faculty and graduate students at participating universities.

While much of the research focus is on a single genus (Rhododendron) at the whole plant level, our findings are broadly relevant to other woody plant species or to other levels of investigation (molecular, cellular, or community).

Rhododendrons share many biological features in common with other members of Ericaceae, the heath family, which includes 120 genera (2,500+ species) that are valued throughout the world as native plants, fruit crops, and ornamental garden plants.