2020 was the final year of a three-year project evaluating annual and herbaceous perennial landscape plants for resistance or tolerance to Phytophthora root or crown rot. Due to the impracticality of existing management options, as well as a lack of information regarding the susceptibility of annual and herbaceous perennial ornamental landscape plants to this disease in the southeastern United States, we evaluated the performance of 59 cultivars of annuals and 53 cultivars of herbaceous perennials in Phytophthora-infested landscape beds across western and central North Carolina over a period of three years.
We identified 26 cultivars of annuals and 22 cultivars of herbaceous perennials that performed well and are recommended for Phytophthora-infested landscapes. Future work may re-evaluate the performance of these plants in other locations to strengthen recommendations. For details about study design, results, and acknowledgements, see this extension publication: https://content.ces.ncsu.edu/phytophthora-root-and-crown-rot-in-the-landscape