Couple of things to do for blackspot. First make sure the rose is getting enough to eat. Mulching with good compost twice a year (spring and fall) will help a lot. Compost tea is very effective against black spot. As is baking soda mixed into soft water (1 tablespoon per quart of water) with a bit of dish detergent also will knock out black spot. Milk mixed 1 part milk to 4 parts water will be very effective against powdery mildew if that becomes a problem. I use raw skimmed milk but any will do.