Around here, hazelnuts are everywhere, from that chocolatey spread in your cupboard to the wild-growing bushes throughout field edges. Hazelnuts grow exceptionally well in our Midwest climate and their nuts command a high price at market, so why don’t we see more hazelnut farms throughout our region?
For starters, the American hazelnut (Corylus americana) is quite literally a hard nut to crack. It produces small nuts with thick shells, making them difficult to process and unsuitable for confectionary markets.
Nearly all commercially grown hazelnuts in the US are European hazelnuts (Corylus avellana), not our native species. They are mainly cultivated in Oregon’s Willamette Valley, where the moderate coastal climate and low pressure of eastern filbert blight (EFB) allow the crop to thrive. This disease is uniquely devastating to European cultivars, but the American hazelnut holds a promising solution within its genome: resistance to the blight.
For decades, plant breeders at Oregon State University and Rutgers University have worked jointly within the Hybrid Hazelnut Consortium to develop crosses between American and European hazelnuts that bring together the best of both species: high quality nuts and resistance to EFB. This collaboration has culminated in the release of several cultivars suitable for midwestern and eastern production including ‘Raritan’, ‘Somerset’, and OSU 541.147 ‘The Beast’. Additional cultivar releases are crucial to add climate and disease resiliency to new orchards throughout the eastern half of the country.
The Center for Agroforestry joined these efforts in 2021 when the first OSU & Rutgers selections were planted at the MU Horticulture and Agroforestry Research Farm. Since then, we’ve started evaluating more than 4,500 seedlings (breeding progeny) from 87 crossed crosses in our hazelnut breeding block. In addition, more than 450 trees spanning 100+ cultivars and selections are under evaluation in our cultivar trial for Midwest suitability. In the coming months, new selections from the Rutgers breeding program will be planted in the trial. We are working collaboratively to produce adapted and disease resistant cultivars that will support the expansion of the US hazelnut industry into midwestern and eastern regions.
Hybrid Hazelnut Consortium breeders Thomas Molnar, PhD, and Shawn Mehlenbacher, PhD, with ‘The Beast’. Photo courtesy of Mehlenbacher et al, 2023.
Breeding progeny refers to trees and shrubs grown from seed that are evaluated annually for their performance. In time, they will either be culled due to suboptimal characteristics or released as new cultivars or seed sources. Selections are promising progeny that have been chosen for having traits of interest and are typically planted in performance trials for further evaluation. If a selection performs well, it will be released to the public as a cultivar. Cultivars are cultivated varieties of a specific plant species that have been proven to consistently produce desired traits.
Fall 2025 marks the first nut harvest from our hazelnut trees in the advanced hybrid hazelnut selection trial. Approximately 30 individual trees produced more than 30 nuts, the minimum needed for kernel evaluations. Yields were lower this year than anticipated due to high cicada damage in the previous growing season. By the end of harvest, total yield per tree will be calculated and nuts will be evaluated. Evaluation includes nut mass, kernel percentage, pellicle removal, and ranking defects such as blank nut, mold, shriveled kernels, kernel fill, and insect damage.
Along with recommended production cultivars, we are working with the Consortium to develop pollinizers for commercial release. Hazelnut flowers require wind pollination from other nearby plants. To ensure peak pollination of production orchards, growers need to plant pollinizers that flower within ideal time windows related to their local climate. Within four years, we expect to release pollinizers specifically suited to Missouri growing contexts.
To round out these breeding activities, our field crew has also been busy establishing hazelnut orchards for integrated agroforestry design demonstration and for investigation into orchard best management practices. This includes a ‘Raritan’ hazelnut alley crop with asparagus, alfalfa, winter wheat, and strawberries and an orchard ground cover research trial. As regionally suited hazelnut cultivars become more readily available, our team is working to answer questions from interested growers and provide support to early hazelnut innovators in the Midwest.
To learn more, register for our first hazelnut workshop on Friday, October 17 at the MU Horticulture and Agroforestry Research Farm.
The workshop will cover regionally suited hazelnut cultivars, best management practices, and integrating hazelnuts into farm design. We’ll also provide ample time for Q&A with our hazelnut research team and special guest speakers and a tour of our advanced hybrid hazelnut selection trial.
Selected scientific publications on hazelnut:
Mehlenbacher, S. A., Smith, D. C., McCluskey, R. L., Snelling, J. W., Molnar, T. J., & Clare, A. (2023). OSU 541.147 Hazelnut. HortScience, 58(3), 333–337. https://doi.org/10.21273/HORTSCI16987-22
Molnar, T.J., Capik, J.M., Mehlenbacher, S.A., Revord, R.S., Braun, L.C. and Fischbach, J.A. (2023). Progress breeding hybrid hazelnuts (Corylus americana × Corylus avellana) in the United States. Acta Hortic. 1379, 125-134 DOI: 10.17660/ActaHortic.2023.1379.19 https://doi.org/10.17660/ActaHortic.2023.1379.19
Molnar, T.J., Honig, J.A., Mayberry, A., Revord, R.S., Lovell, S.T., Mehlenbacher, S.A. and Capik, J.M. (2018). Corylus americana: a valuable genetic resource for developing hazelnuts adapted to the eastern United States. Acta Hortic. 1226, 115-122 DOI: 10.17660/ActaHortic.2018.1226.16 https://doi.org/10.17660/ActaHortic.2018.1226.16
Revord, R. S., Lovell, S. T., Capik, J. M., Mehlenbacher, S. A., & Molnar, T. J. (2020). Eastern Filbert Blight Resistance in American and Interspecific Hybrid Hazelnuts. Journal of the American Society for Horticultural Science, 145(3), 162–173. https://doi.org/10.21273/JASHS04732-19
Revord, R.S., Molnar, T.J., Hlubik, D. and Meier, N.A. (2023). Revisions to class-based eastern filbert blight ratings to reflect variation in quantitative resistance. Acta Hortic. 1379, 141-148 DOI: 10.17660/ActaHortic.2023.1379.21 https://doi.org/10.17660/ActaHortic.2023.1379.21
Webber, J.B.; Putnam, M.; Serdani, M.; Pscheidt, J.; Wiman, N.; Stockwell, V. (2020). Characterization of isolates of Xanthomonas arboricola pv. corylina, the causal agent of bacterial blight, from Oregon hazelnut orchards. Journal of Plant Pathology. 102, 799– 812. https://doi.org/10.1007/s42161-020-00505-6
Wiman, N.; Webber, J.B.; Wiseman, M.; Merlot, L. (2019). Identity and pathogenicity of some fungi associated with hazelnut (Corylus avellana L.) trunk cankers in Oregon. PLoS ONE 14(10): e0223500. https://doi.org/10.1371/journal.pone.0223500
