Vincas are dying
I have vinca plants on my hill as a ground cover. They have survived on that hill for at least 20 years. I have not been watering them in the past or this summer. Large patches have turned brown and they are dying. How can i figure out why they are dying? Could it have been the heat waves we had this summer?
Vinca is susceptible to two fungal diseases, Phomopsis and Phoma Dieback of Vinca, which tend to be prevalent during rainy seasons like we had last year and into this spring. Then we had drought and high temperatures which are stressful to plants, making them more prone to diseases.
These fungal diseases attack through wounds, spread by water, and are favored by high levels of moisture. Unfortunately, the only way to deal with it is to thin the groundcover out severely. You could even try mowing high over the area in the spring and raking out the debris. See our webpage for additional information, https://extension.umd.edu/hgic/topics/phomopsis-and-phoma-dieback-vinca.
If you are near a woodland area, Vinca is no longer recommended as a groundcover because of its invasiveness in natural areas. It out-competes native plants that are an important part of the ecosystem. http://mdinvasives.org/iotm/jan-2019/
If you find that this disease problem persists, you might want to consider a different type of groundcover. Refer to our lists of recommended plants for shady slopes (https://extension.umd.edu/hgic/topics/native-plants-shady-slopes) and groundcovers (https://extension.umd.edu/hgic/topics/groundcover-list).