
I would encourage you to feed your rosebushes with a good organic based rose food. Also consider giving them some kelp and alfalfa meal too. Here is a link to an article on feeding rosebushes for you to check out: https://www.gardeningknowhow.com/ornamental/flowers/roses/best-rose-fertilizer.htm and this one too: https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-fertilizer.htm
As for their leaves spotting, you may have the Black Spot fungus. This fungus really saps the strength out of the rosebushes. That will need to be treated with a good fungicide. Here is a link to an article on that for you as well: https://www.gardeningknowhow.com/ornamental/flowers/roses/black-spot-roses.htm and check this one out too concerning diseases of rosebushes: https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-bush-diseases.htm .