The spotted yellow leaves are the result of black spot disease. Knock Out roses, in general, are quite resistant (not immune) ...

I just wanted to take a minute and give you an update on my Knockout roses. It has been a struggle, but they are finally looking better))) So, just take this as a note of encouragement ...

SHREVEPORT, Louisiana (KTBS) — Both Knockout and Drift roses have become favorites in both residential and commercials landscapes due to their low maintenance and impressive blooming cycles.