This spring we got three nice white fan flowers to put in a half barrel pot. We put something different in this pot every year and there has never been any major issue with any plants. For the first two months this spring/summer the fan flowers looked great. They grew quickly and bloomed very well. Then, two or three weeks ago, one of them began wilting. I checked the stem and discovered the base of one of the branches was turning dark. I cut off the bad branch, but the dark colored part went into the crown. Over the next week the fungus or disease or whatever it was spread and moved up the other branches, killing the rest of the plant. Last weekend a second white fan flower began showing the same problem. It wilted badly so I had to yank it out. Today, the third white fan flower is showing the same problem. The base of the stem is turning dark and many of the stems and leaves are wilting. Does anyone have any idea what might be going on with these plants? Could the plants have come with some kind of disease or fungus in the pots? It should not be an issue of too much moisture leading to rot. We don't overwater plants. Our other pot of purple fan flowers continues to look great and we've grown purple fan flowers in the past with no issues. When the first white fan flower went bad we did replace it with a new one from a different garden center, so we'll find out over the next couple months if there is something in the barrel that infects that one as well.