Question
Hello,
I live in Cincinnati, OH. (Don't know the zone).
I added a total of five knockout rose bushes to my garden during the past three years. They all did very well during the first two years. In the spring of 2008, there was a late frost and the outer leaves were hurt, which I pruned. Yet, the knockouts  bloomed and grew very well. However, during the summer the rose production vaned and then pretty much stopped, except for one bush (not as prolific as last year though), despite of cutting the dead flowers off. During the summer, the leaves turned partially yellow or reddish, and showed uneven holes. I cannot find any lice or other damaging organisms on the vines. The growth of new branches pretty much stopped. We did have some dry weather since late August, but I watered the roses. By the way they are slightly elevated where they are planted.
I hope this is enough information for a diagnosis, and I am very grateful to be able to ask an expert in the field for advice. It is quite depressing to have an 'easy rose bush' failing in a usually successful garden.

Answer
If roses are doing well and then seem to stop acting like they should, it is usually because they have gone into stress. Stress is caused by weather suddenly getting very hot, or no rain for a long time. Both of these conditions cause a rose to not function as it should.  There is nothing you can do to stop the weather but you can help the rose ride out the troubled period. When there is no rain or the temperature is very hot, make sure when you water that you get it at least 8 inches deep beside the rose. DON'T give a rose any fertilizer when it is hot or even spray it as the rose roots have temporary shut down and can't take the fertilizer up and the leaves can't  cope with the spray. It will just burn or damage the leaves which have probably because of the stress, turned yellow. I think you will find that even if the roses went into stress they will not die but come back with a bang in the next spring.