There are the beginnings of red spots following the vein of the green leaf, which turn yellow and fall off. My mother is also having this problem. Our plants are large green and full of blooms. They seem to not like the really early dry and hot season we are having. We have 50 yrs experience with roses but never have seen this before. Thank you, Deborah
Double Red Knockout Roses
It sure sounds like you have a beetle problem. The red spots are where they have drilled in their snouts to feed on the juices in the veins. I would recommend buying some Bayer Tree and Shrub Granules and apply those at the base of each rosebush working it into the soils lightly and water it in. Follow the directions on the label for ornamental plants if they do not list roses. That should clear things up. There are other things that make the foliage turn yellow and fall off, but the red spots following the veins sounds like the insect issue.