Phytophthora root and crown rot is an emerging, and devastating disease that affects lavender by causing root decay, wilting, and plant decline, leading to significant losses in commercial production. This research evaluates the efficacy of various fungicide applications in managing the disease under controlled greenhouse conditions. Results indicate that specific fungicide treatments can significantly reduce disease severity, enhancing plant survival and vigor.
P. nicotianae is one of the most studied species of Phytophthora. It was first described in 1896 as a cause of disease on tobacco, and it is now known to be pathogenic to plants in 255 genera and 90 families. In addition to causing problems on English lavender in the United States, it also has affected lavender plants in Spain, Italy, Bulgaria, and Greece. Symptoms of infection include grey discoloration and wilting of the foliage, discoloration and rotting of the roots, vascular discoloration, and plant mortality.
By identifying the most effective chemical management options, this study offers practical solutions for lavender growers to mitigate disease impact and maintain high-quality production. The findings contribute to the development of integrated disease management approaches, combining fungicides with cultural practices to improve long-term plant health.
Dr. Dlugos, who received a PhD. from Clemson University, is currently a Senior Research Specialist in plant breeding at Holden Forests & Gardens. His expertise is in the management of plant diseases. He is currently working on a plant breeding program for eastern hemlock.
This study is part of a larger research project to identify the species of Phytophthora
causing root and crown rot on lavender and how this disease can be managed to
minimize losses and promote sustainability of lavender production around the country.
This project is ongoing and is being conducted in collaboration with the US Lavender
Growers Association ( https://www.uslavender.org/ ) and was supported by the USDA
Floriculture and Nursery Research Initiative.
Dr. Dlugos, who received a PhD. from Clemson University, is currently a Senior Research Specialist in plant breeding at Holden Forests & Gardens. His expertise is in the management of plant diseases. He is currently working on a plant breeding program for eastern hemlock. Dr. Dlugos conducted this research as part of his dissertation project.
Dr. Bridges is a Distinguished Alumni Professor of Mathematics and Statistics at
Clemson University. He has both teaching and research responsibilities and mentors
graduate students about statistics and data analysis.
Dr. Jeffers is a Professor of Plant Pathology and State Extension Specialist at Clemson University in South Carolina. He has responsibilities for managing diseases on ornamental plants and trees grown in nurseries, greenhouses, and landscapes.
The full story can be found on the ASHS HortScience electronic journal website at: https://doi.org/10.21273/HORTSCI18302-24
Established in 1903, the American Society for Horticultural Science is recognized around the world as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting and encouraging national and international interest in 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 - scientists, educators, students, landscape and turf managers, government, extension agents and industry professionals. ASHS members focus on practices and problems in horticulture: breeding, propagation, production and management, harvesting, handling and storage, processing, marketing and use of horticultural plants and products. To learn more, visit ashs.org.
