A friend has a problem with a Hansa rugosa rose & she asked if I knew what the problem might be but it is something that I haven't seen before. Has anyone had a similar problem with Hansa or another Rugosa? (The soils in this area tend to have a pH slightly below 6 which is what Rugosa's are usually happy in). Below is her description of the problem: Thanks.

"Last season we had trouble with the blossoms turning brown and messy right before blooming. The plants were healthy-looking, with an occasional yellowing of leaves or stems, which were consistently removed. We just weren't sure why this kept happening, whether there was a virus causing this, or a deficiency of some sort. There was always a good and vigorous blossom set, they just would never fully open, they 'd get brown, limp and yucky and we'd cut the whole cluster off."