I have one knockout rose bush I planted 2 years ago and two I planted this year. All now have the leaves on them that look like there is something eating them. Looked and cannot see any evidence of any insects. I have sprayed them with water mixed with dish soap. That did nothing. I then purchased Ortho Rose spray. Neither worked. Today, I noticed that it looks like the leaves are dying. This is my first experience growing knockout roses. The bush that is 2 years old was doing great. It survived our Wisconsin winter and has grown. They are planted on the east facing side of my house. Am hoping you can help me.
Knockout Roses Disease
It sounds like you have a tenacious bug problem, likely some type of beetle. The attack sounds pretty much full on, so I would do two things in such a case. I would spray the rosebushes with Bayer Advanced Complete Insecticide and then also give them a treatment of Bayer Tree & Shrub granules. This two pronged approach should get them back to good health and performance.