Vascular streak dieback and stem canker: Emerging threats to U.S. redbud nurseries
Recent research led by Dr. Fulya Baysal-Gurel of Tennessee State University is shedding new light on two significant threats to redbud (Cercis canadensis) production in U.S. nurseries. The studies address both the economic impact of vascular streak dieback (VSD) and the management of stem canker caused by Botryosphaeria dothidea—diseases that together pose mounting challenges for growers nationwide.
The first study quantified the financial losses associated with VSD, an emerging disease that affects redbud, maple, dogwood, and more than 25 genera of ornamental and woody plants. The research team conducted a multi-state survey of growers to evaluate production losses, increased labor costs, and management practices used to mitigate disease spread.
Results highlight that VSD has become a serious economic concern, reducing plant health and marketability while increasing operational expenses. These insights will help guide the development of strategies to strengthen disease control and promote more sustainable production practices across the nursery industry.
A companion study evaluated a range of fungicides, biofungicides, and plant-based extracts for controlling stem canker caused by Botryosphaeria dothidea, a common pathogen that can weaken redbuds and reduce plant quality. The research identified several promising treatments that can improve disease management and help producers maintain high-quality nursery stock.
Woody ornamentals such as redbud are a cornerstone of the $4.5 billion U.S. nursery industry,with California, Florida, Michigan, Oregon, and Texas among the top-producing states. Approximately 86% of the market value is generated through wholesale operations, underscoring the importance of maintaining healthy, market-ready plants.
This research provides timely insights for growers and industry stakeholders seeking to safeguard plant health and profitability in the face of new and reemerging plant diseases. The findings contribute to ongoing efforts at Tennessee State University to support agricultural sustainability and the economic strength of nursery operations regionally and nationally.
According to Dr. Baysal-Gurel, "After hearing directly from producers in the industry who were seeing VSD in the field, we took action to try to quantify the losses. And the losses have been significant."
Dr. Fulya Baysal-Gurel is Associate Dean for Research, and Associate Professor of plant pathology at Tennessee State University's College of Agriculture. Her research interests include plant pathology, mycology, plant disease diagnosis, plant disease management, integrated pest management and biological control of plant diseases and biopesticides.
More information:
Pratima Subedi et al, Evaluation of Fungicides, Biofungicides, and Plant-Based Extract for the Management of Stem Canker Caused by Botryosphaeria dothidea in Eastern Redbud (Cercis canadensis), HortScience (2025). DOI: 10.21273/hortsci18841-25
Kumuditha Hikkaduwa Epa Liyanage et al, Investigating the Economic Impact of Emerging Vascular Streak Dieback Threat to Redbuds in the US Nursery Industry, HortScience (2025). DOI: 10.21273/hortsci18589-25
Provided by American Society for Horticultural Science
