In Portland, this Spring, we have had heavy rains and warmer temps. The roses, in our garden, look quite stressed. Some rose buds have the “balling” signs (thick, gluey outer coating stopping the rose from opening). This bud had the moss like growths popping out from the base of the frustrated petals. I have never seen this before. Warmer, drier weather has arrived for a bit, so I hope this remedies what ails them.
Pull a flower apart and look careful for insects. They may be suffering from a bad aphid infestation.