We are on the second year of evaluating herbaceous ornamental plants for resistance or tolerance to Phythophthora root rot, crown rot, and foliar blight. We are repeating our study from 2018: A sustainable approach to Phytophthora-infested landscape beds and re-evaluating plant species and cultivars that had a performance rating of ‘Excellent’ or ‘Good’ from 2018. Additionally, we are evaluating new plant species and cultivars to make stronger recommendations for alternative plants that can be used in landscape beds infested with Phytophthora root rot, crown rot, and aerial blight.
Our study aims to provide a sustainable approach to landscapers by evaluating multiple cultivars of annuals and herbaceous perennials that are tolerant or resistant to Phytophthora. Plants were selected based on desirability and prior observations of tolerance or resistance to Phytophthora and other common diseases found in ornamental plants (ex. downy mildew, powdery mildew, etc.).
Three landscape beds were established to ensure consistency within the confines of one growing season. Each bed is established in:
- Mountain Horticultural Crops Research and Extension Center, Mills River, NC
- Mountain Research Station, Waynesville, NC
- Piedmont Research Station, Salisbury, NC
Each bed is approximately 200ft2 and filled with a blend of screened top soil and compost. To infest the soil, inoculum of three species of Phytophthora (P. nicotianae, P. drechsleri, P. tropicalis) known to cause disease on herbaceous ornamentals will be added to each bed. Plants will be rated regularly for disease incidence and severity based on the percentage of the plant showing symptoms of root rot, crown rot, or aerial blight.
Enjoy some photos below and check back for project updates!
Stay tuned for project updates and results!
To learn more about Phytophthora on ornamental plants and how to manage for this disease, please view the NCSU Disease Fact Sheet for more information.