The first Focus on Forage webinar in the 2026 series, Focus on Forage Management, features research-based resources and management strategies to keep forage systems productive over time.
Presenters are Dr. Marta Kohmann, UW–Madison forage systems agroecology extension specialist and assistant professor; Dr. Natasha Rayne, UW–Madison soil fertility extension specialist and assistant professor; and Dr. Luiz Ferraretto, UW–Madison dairy nutrition extension specialist and associate professor.
Expand each section below for recordings of and resources related to each talk. To find more information about the Focus on Forage webinar series, visit the Focus on Forage website.
An Overview of Winterkill in Alfalfa
Presented by: Dr. Marta Kohmann, University of Wisconsin–Madison
Dr. Marta Kohmann, UW–Madison Extension forage agroecosystems specialist, provides a comprehensive overview of alfalfa winterkill—what it is, why it happens, how to diagnose it, and how to manage stands affected by winter injury. She explains the three primary types of winterkill (frost heaving, tissue damage, and suffocation), discusses indirect effects such as disease and reserve depletion, and highlights environmental conditions that increase risk. Dr. Kohmann also shares recent research, management strategies to reduce winter injury, and practical steps for evaluating damaged stands and choosing next actions.
Resources:
- Leep, R. H., Andresen, J. A., & Jeranyama, P. (2001). Fall dormancy and snow depth effects on winterkill alfalfa. Agronomy Journal, 93, 1142-1148.
- Li, Z., Li, X., & He, F. (2023). Non-structural carbohydrates contributed to cold tolerance and regeneration of Medicago sativa L. Planta, 257, 116.
- Ninagawa, T., Eguchi, A., Kawamura, Y., Konishi, T., & Namuri, A. (2016). A study on ice crystal formation behaviour at intracellular freezing of plant cells using a high-speed camera. Cryobiology, 73, 20-29.
- Perfect, E., Miller, R. D., & Burton, B. (1988). Frost upheaval of overwintering plants: A quantitative field study of the displacement process. Arctic and Alpine Research, 20, 70-75.
- Russel, W. E., Olsen, F. J., & Jones, J. H. (1978). Frost heaving in alfalfa established on soils with different drainage characteristics. Agronomy Journal, 70, 869-872.
- Takahashi, D., Willick, I., Kasuga, J., & Livingston III, D. P. (2021). Responses of the plant cell wall to sub-zero temperatures: A brief update. Plant & Cell Physiology, 0, 1-9.
- Van Keure, R. W. (1988). Frost heave of alfalfa as affected by harvest schedule. Agronomy Journal, 80, 626-631.
- Baumgartner, Landon. (2025). Evaluating alfalfa stands for profit in spring 2025. Crops and Soils, Division of Extension. https://cropsandsoils.extension.wisc.edu/articles/evaluating-alfalfa-stands-for-profit-in-spring-2025/
- Centinari, M. (2023). Understanding and Preventing Spring Frost and Freeze Damage to Grapes. https://extension.psu.edu/understanding-and-preventing-spring-frost-and-freeze-damage-to-grapes
- Cisgrove, Dennis, & Undersander, Dan. (2003). Evaluating and Managing Alfalfa Stands for Winter Injury. https://fyi.extension.wisc.edu/forage/evaluating-and-managing-alfalfa-stands-for-winter-injury/
- Interactive tool. Calculate your risk of alfalfa winter injury, by Craig Shaeffer. https://umn.qualtrics.com/jfe/form/SV_d4rADQaj9D5sHdQ
- Sheaffer, C. Winter hazards to forages: Heaving. Minnesota Crop News. https://blog-crop-news.extension.umn.edu/2023/03/winter-hazards-to-forages-heaving.html
Unlocking the Nutrient Value of Manure in Alfalfa Production
Presented by: Dr. Natasha Rayne, University of Wisconsin–Madison
Dr. Natasha Rayne explores how to unlock the full nutrient value of manure in alfalfa production. She begins with an overview of key nutrient needs in alfalfa—especially nitrogen, phosphorus, potassium, sulfur, and boron—and explains how alfalfa’s high nutrient demand makes manure a valuable but sometimes challenging fertilizer source.
Dr. Rayne discusses optimal nutrient guidelines, soil test interpretation, and how manure applications influence crop nutrition, winter survival, and stand longevity. She also highlights the risks of manure use, including compaction, weed pressure, and nutrient runoff, while reviewing research on application timing and low-disturbance manure injection. The session concludes with practical recommendations for integrating manure into alfalfa systems while protecting crop health and the environment.
Feeding Considerations Without BMR Corn
Presented by: Dr. Luiz Ferraretto, University of Wisconsin–Madison
Dr. Luiz Ferraretto, UW–Madison Extension dairy nutrition specialist, discusses feeding strategies and forage alternatives in light of Corteva’s discontinuation of BMR (brown midrib) corn hybrids. He reviews why BMR silage has been so valuable—particularly its consistently higher fiber digestibility and improved dairy cow intake and milk production—and explains why BMR is difficult to replace directly.
Dr. Ferraretto highlights emerging options such as short‑stature corn hybrids, which show early promise for improved digestibility and starch content, as well as the potential of highly digestible cover crop silages like rye, triticale, and vetch mixtures. He also emphasizes management practices and the importance of continued research as the dairy industry adapts to feeding without BMR corn.
About This Series
Focus on Forage is a free, annual spring webinar series highlighting researcher and farmer strategies to optimize forage yield, quality, and profitablity in Wisconsin. Watch recorded content, join our mailing list, and sign up for future webinars online.
Forage Production and Management Resources
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