Hi Peter,
The only things I know about roses are:
1. They don't last long in a vase in hot weather.
2. Only pick them from a stranger's garden if you can run fast.
3. In Qld, roses are grown at the end of vineyard rows. They are more suseptable to fungal attack and when they show signs, its time to treat the grape vines.
Yeah I know! A waste of oxygen.
Cheers Marty