to get rid of blackspot there are two fings ya need to do ,first the pest starts in late spring when the spores are in the ground from over wintering get washed onto the plants by rain etc then when it gets hot they spread through the plant and the infected leaves fall off and they then reinfect the plant again . so clean up all rubbish below the plants n then dont intentionally splash the plants with ya watering get down low on em, and then when the plants pack up for the winter make sure ya clean up all the rubbish,if ya see dead or dyin leaves on the plants pick em off and burn em .put a mulch around the plants of paper ,carboard discs is good this will soak water in but not let dodo get washed up
then ya can treat em with a systematic fungicide such as rose clear this will do the job follow the destructions on the carton ... hit it before it gets a real hold
for aphids you use washing up liquid as they cant breathe through it ......this werks on all aphids including black fly on beans