Brad: Use a rose gun spray, such a Scotts Rose Clear Gun, available from garden centres, that is effective against blackspot, powdery mildew and rust. It comes in a ready-to-use form and needs to be applied every fortnight. It also contains bifenthrin which will deal with the greenfly as well. This is a versatile spray for roses but, please be aware, it is not for use on edible plants, so read the instructions.