stem blight on vinca minor (periwinkle/myrtle)
My beautiful 3-year-old patch of vinca minor got a nasty fungus a month or so ago. It was beautiful,full and healthy and I didn't realize what was going on under it until it had really gotten bad. Now I've lost a lot of it and am still losing it. I've been pulling the infected parts out, and I put fungonil on it 2 times in the past 2 weeks. It may be slowing down a little, but I'm still yanking infected stuff out. I have some areas that still look pretty good. It's gotten kind of dry here in NY. I don't want to lose the good stuff, but I also don't want to encourage the fungus. Should I water or not? If yes, should I wait until it starts to look a little wilted, or will I have waited too long if I do that. Also, has anyone ever gotten a bad case of fungus on vinca and gotten rid of it and eventually the whole patch looked full and healthy again? I'm sick about this. If I do get it back, should I use a fungicide as a preventative measure in the cool, wet weather of spring and fall? How dry can I let a well-established patch of vinca get without losing it?