Tower Hotline: 440.602.3838 | Phone: 440.946.4400

Stephen L. Krebs, PhD

440.602.3831 | 440.428.3966 (April-November)

Ph.D., Michigan State University, Plant Breeding and Genetics/Horticulture

Adjuct Appointments:

Adjunct Associate Professor, Department of Horticulture and Crop Sciences, Ohio State University

Adjunct Associate Professor. Department of Horticulture, Iowa State University

Stephen L. Krebs, PhD

Research Interests

My job is to manage The Holden Arboretum’s David G. Leach Research Station, a satellite facility maintained for horticultural research on a 30-acre property in Madison, Ohio, 40 minutes east of Holden’s main Kirtland campus. The Leach Station is staffed and equipped to support extensive and diverse display gardens, in addition to large breeding populations and research plots. The station remains committed to breeding and evaluating superior rhododendrons for continental climates (i.e. cold winters and hot summers). In addition, the traditional breeding program is complemented by a research component focused on adaptations of rhododendrons to biotic and abiotic stresses, such as winter freezing injury to leaves and buds, ‘bleaching’ of leaves (photoinhibition) under excessive light, and diseases caused by fungal pathogens (Phytophthora root rot and powdery mildew).

Current Projects

  • How much natural variation exists among Rhododendron species for tolerance to a particular stress? MORE
  • What are the genetic and physiological determinants of this tolerance? MORE
  • Can stress tolerance be transferred via conventional or modern techniques to a new generation of hybrids that have improved landscape performance under stressful conditions? MORE
  • How is expression of these traits influenced by other key features of woody plant biology, such as juvenility and dormancy? MORE

Recent Publications

Peng, Y, W Lin, H Wei, SL Krebs, R Arora (2008) Phylogenetic analysis and seasonal cold acclimation-associated expression of early light-induced protein genes of Rhododendron catawbiense. Physiologia Plantarum132: 44-52. PDF

Jones, JR, TG Ranney, NP Lynch, and SL Krebs (2007) Ploidy levels and relative genome sizes of diverse species, hybrids, and cultivars of rhododendron. Journal of the American Rhododendron Society 61: 220-227. PDF

Kalberer, SR., R Aurora, N Leyva-Estrada, and SL  Krebs (2007) Cold hardiness of floral buds of deciduous azaleas: dehardening, rehardening, and endodormancy in late winter. Journal of the American Society for Horticultural Science 132: 73-79. PDF

Wei, H, AL Dhanaraj, LJ Rowland, Y Fu, SL Krebs, and R. Arora (2005). Comparative analysis of  expressed sequence tags from cold-acclimated and non-acclimated leaves of Rhododendron catawbiense Michx. Planta 221: 406-416. PDF

Krebs, SL (2005). Loss of winter hardiness in R. ‘Supernova’, an artificial polyploid. J. American Rhododendron Society 59: 74-75.

Marian, CO, SL Krebs and R Arora (2004).  Dehydrin variability among Rhododendron  species: a 25- kDa  dehydrin is highly conserved and associated with cold acclimation across diverse species. New Phytologist 161: 773-780. PDF

Krebs, SL and M Wilson (2002) Resistance to Phytophthora root rot among contemporary  rhododendron cultivars. HortScience 37: 790-792. PDF

Lim, CC, SL Krebs, R Arora (1999) A 25 kD dehydrin associated with genotype- and age-dependent leaf freezing tolerance in Rhododendron: a genetic marker for cold hardiness? Theoretical and Applied Genetics 99: 912-920. PDF

Krebs, SL (1996) Normal segregation of  allozyme markers in complex rhododendron hybrids. Journal of Heredity 87:131-135.