Posted: 07/06/2014 at 11:27
Hi Nut, I've had a look at my Dad's really old rose books, R.spinosissima is supposed to be really tough and will cope with impoverished soil but if that and Moyesii are both showing signs of chlorosis I doubt it's lack of general food. Book says most likely to be lack of a trace element usually iron, magnesium, manganese, boron. Iron is usually the culprit this can happen when there is too much lime in the soil or you are growing on chalk.
I would imagine feed specifically for roses will contain trace elements, rather than treating with sulphate of iron, but they do suggest a spray of seq' iron on foliage can also help.