Rose of Sharon
We have a rose of sharon that appears very green and healthy all summer but has developed random yellow leaves about the time it starts to bloom (a week or so ago in zone 6). This has happened every years since we moved here. There seems to be a dark spot on some of the yellow leaves but not all of them. I don't think it is a water issue as the yellow leaves are scattered throughout the bush. I was thinking maybe a fungus? Is rose of sharon particularly susceptible to some disease or pest?