[quote="Susan_in_SB"] My guess is lack of water. Often, drip systems don't provide adequate water for roses. I also noticed that one of your roses is right next to a stucco wall. If that wall is facing south, and gets full sun, it could produce way too much heat for your rose. I also noticed that there is a purple ground cover right next to one of your roses, and a large agave; they might be providing some competition for the water. [/quote
That's what I thought, too, Susan. Also, I think a good deal more mulch would help hold the moisture in the soil. At least, three inches in a hot climate is necessary.