I have two potted vincas in PHX, AZ. They have been full, green, and healthy with massive amounts of blooms for the last few years. This year, however, one of them started yellowing and dropping leaves, to the point that it is now this spindly bare thing hardly recognizable as the vinca it once was (see pic) It does get some new growth, it's just yellow and the plant never fills out. I read something about a fungus or rot and thought maybe that's the issue? Well, now the second one is doing the same thing. The yellow leaves have brown spots on them. Any ideas? I haven't seen any other pics of diseased vincas that seem comparable to mine. Is it possible that whatever this is may have spread from one plant to the other? Because I did recently move the second plant to the backyard where the first one is. They aren't close together, but they are now both in the same yard. Any help would be MUCH appreciated. Thanks!