not sure about using jeyes. you can buy a specific rose fungicide. I think it is called rose clear. the black spot you have is a recognised rose fungal infection. rust is also fungal. keep picking up the infected leaves but don't compost them. either burn them or put them in the household waste.

The problem with using Jeyes fluid is that you probably don't know what strength to mix unless you can find information in an old gardening book.

Personally, unless it is seriously threatening the health of a whole bed of roses, the best thing is just to pick off and burn/bin the affected leaves. Followed by improving the conditions to reduce the likelihood of the problem recurring.

I'd go with Rose Clear too - found it very effective.

I have only known it be used for Black Spot I've read that one teaspoon per gallon is about right and in 2005 the Telegraph recommended it for black spot, sprayed on leaves. I got this from internet research, too, from the RHS forum 2005. It is harmful to animals if ingested. This suggests it would kill vine weevil grubs and harm anything that ate them. And it's the best cat repellent i ever used.