I live in Tucson, Az. My roses are looking great right now except some of them (not all) are sprouting blooms that have a burnt edge appearance. They seem to stay tight in the rolled up bud and don't really open up well. It looks as if the edges have been seered with something. Any ideas?? They don't seem to have bugs on them and the leaves are green and healthy looking. Also they have many, many buds. Some of my roses don't have this and some do. I would appreciate any ideas on this.