Second year: Phytophthora on Herbaceous Ornamentals

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.

Project Summary

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:

  1. Mountain Horticultural Crops Research and Extension Center, Mills River, NC
  2. Mountain Research Station, Waynesville, NC
  3. 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. nicotianaeP. drechsleriP. 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.

Click here to see the full list of plants we are evaluating in 2019

Enjoy some photos below and check back for project updates!

Planting the landscape bed at the Mountain Horticultural Crops Research and Extension Center

Planting the landscape bed at the Mountain Horticultural Crops Research and Extension Center on May 29, 2019

Landscape bed at the Mountain Horticultural Crops Research and Extension Center, Mills River, NC

Landscape bed at the Mountain Horticultural Crops Research and Extension Center, Mills River, NC

Landscape bed at the Piedmont Research Station, Salisbury, NC

Landscape bed at the Piedmont Research Station, Salisbury, NC

Landscape bed at the Mountain Research Station, Waynesville, NC

Landscape bed at the Mountain Research Station, Waynesville, NC

Amanda Scherer (Post-doc) is helping dig trenches in the soil before adding the Phytophthora inoculum

Amanda Strayer-Scherer (Post-doc) adding Phytophthora inoculum to the Piedmont Research Station landscape bed on June 13, 2019

Phytophthora inoculum going into the Piedmont Research Station bed on June 12, 2019.

Phytophthora inoculum going into the soil at the Piedmont Research Station bed on June 12, 2019

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.

This entry was posted in NC State. Bookmark the permalink.