Can you recommend some rose cultivars that are resistant to black spot?
Several roses that are Black Spot resistant that I have had success with:
Knock Out Rose series
If you go online and type in Black Spot Resistant Roses, you will find long lists of Ramblers, Shub, Polyanthas and Hybrid Tea roses that are resistant.
We are also uploading this attached list from the Philadelphia Rose Society, some recommended low maintenance roses to grow in the Philadelphia area.