I have a lot of yellow leaves too and I suspect these are the older leaves and the heat we're having now is making them yellow. I think you may also not be watering enough. Once a week when there's no rain and it's warm doesn't really seem adequate in our dry climate. You should be able to feel some moisture beneath the mulch without having to go down several inches. Try watering 2-3 times a week and see if that helps.

Well with the watering I do a deep water. I'm giving them 1" of water. Also the type of soil I have holds on to water pretty well. I last watered the roses on Thursday and the soil under the leaves is still moist and it will basically stay that way until next Thursday.

This post was edited by NickRose on Sun, May 4, 14 at 15:50

I've had this same thing and people here commented about a similar situation that appeared to be mosaic but it is not. It's on lower old leaves where there are other signs of stress. It's a water/heat stress problem.

1. Did you just get through a heat wave like we did. That will do it.

2. The other thing to do is check the back of a few of the leaves for the orange pustules indicative of Rust.

1 more likely than 2 at this time of year.

@hoovb- We did have 3 days in the high 80's to low 90's. But the top of the soil was moist. At one point I did see rust on a few of the plants.