Phytophthora root and crown rot, a devastating disease affecting English lavender, is causing significant losses in commercial production due to root decay, wilting, and plant decline. Recent research conducted under controlled greenhouse conditions has evaluated the efficacy of various fungicide applications in managing this disease. The study’s results indicate that specific fungicide treatments can significantly reduce disease severity, enhancing plant survival and vigor.
The emergence of Phytophthora rot on lavender is not isolated to the United States. This disease has also impacted lavender crops in Spain, Italy, Bulgaria, and Greece. Symptoms include grey discoloration and wilting of the foliage, discoloration and rotting of the roots, vascular discoloration, and ultimately, plant mortality. The study aims to identify the most effective chemical management options, offering practical solutions for lavender growers to mitigate disease impact and maintain high-quality production.
Understanding Phytophthora: A Historical Perspective
P. nicotianae, one of the most studied species of Phytophthora, was first described in 1896 as a cause of disease on tobacco. It is now known to be pathogenic to plants in 255 genera and 90 families. The spread of this pathogen to lavender highlights the need for effective management strategies to protect this valuable crop.
Dr. Dlugos, a Senior Research Specialist in plant breeding at Holden Forests & Gardens, led the study. His expertise in plant disease management is crucial for developing integrated disease management approaches that combine fungicides with cultural practices to improve long-term plant health.
Collaborative Efforts and Research Support
This study is part of a larger research project aimed at identifying the species of Phytophthora causing root and crown rot on lavender. The project seeks to minimize losses and promote the sustainability of lavender production across the country. Conducted in collaboration with the US Lavender Growers Association, the research is supported by the USDA Floriculture and Nursery Research Initiative.
Dr. Dlugos conducted this research as part of his dissertation project, contributing valuable insights into the management of this disease. Dr. Bridges, a Distinguished Alumni Professor of Mathematics and Statistics at Clemson University, provided expertise in statistics and data analysis, ensuring the robustness of the study’s findings.
Implications for Lavender Growers
The findings from this study are expected to have significant implications for lavender growers. By identifying effective fungicide treatments, the research provides a foundation for developing comprehensive disease management strategies. These strategies will help growers maintain high-quality production and reduce economic losses due to Phytophthora rot.
Dr. Jeffers, a Professor of Plant Pathology and State Extension Specialist at Clemson University, emphasized the importance of managing diseases on ornamental plants and trees in nurseries, greenhouses, and landscapes. His involvement in the study underscores the collaborative effort required to tackle this complex issue.
Looking Forward: Sustainable Lavender Production
The ongoing research into Phytophthora management is a critical component of sustainable lavender production. By integrating fungicide applications with cultural practices, growers can enhance plant health and reduce the impact of this devastating disease. The study’s findings contribute to a broader understanding of disease management in horticulture, offering hope for improved practices in the future.
The full story can be accessed on the ASHS HortScience electronic journal website at: https://doi.org/10.21273/HORTSCI18302-24. Established in 1903, the American Society for Horticultural Science (ASHS) is recognized as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting scientific research and education in all branches of horticulture.
Comprised of thousands of members worldwide, ASHS represents a broad cross-section of the horticultural community, including scientists, educators, students, landscape and turf managers, government, extension agents, and industry professionals. ASHS members focus on practices and problems in horticulture, from breeding and propagation to marketing and use of horticultural plants and products. To learn more, visit ashs.org.
