Vinca – Rhizoctonia fungus
Q: The vinca patch in my yard has a fungus that makes the stems turn black. The leaves are first yellow and then turn brown. It appears in patches with no specific pattern. Is there anything I can do to stop it?
A: Your vinca has Rhizoctonia dieback. It’s a common disease when vinca foliage is regularly wet from rain or is in the path of rainwater. About all you can attempt is to keep the foliage as dry as possible. Hot weather usually stops the disease’s progression. If you must DO something, spray with Immunox fungicide and give the whole patch a light feeding with 10-10-10 now.