My new knockout roses have little holes in the leaves. What is it and what can I do?
It is likely a type of beetle that is damaging your rose foliage. You should be able to gain control of the situation by spraying the rosebushes with a product called Bayer Advanced Complete Insecticide. Another method would be to give all the knockout rosebushes a treatment of Bayer Tree & Shrub Granules, it is a systemic product that does a very good job.