In JAC wrote:
I hope I use the terminilogy correctly. I would like to treat my roses
by watering them with the blackspot treatment as opposed to spraying
them. Is this possible. If so, what is best for this?

Triforine, which is the only systemic black spot chemical I am aware of,
cannot work by being watered into the soil. Its systemic effect is
limited to penetrating the immediate leaf area where it is sprayed - it
doesn't move through the plant stems via sap like some insecticides do.

I suppose you could water it onto the leaves with a fine shower head,
but that would be pretty wasteful.