The spotted yellow leaves are the result of black spot disease. Knock Out roses, in general, are quite resistant (not immune) to black spot disease. During wet weather conditions, however, even ...

In May, rust typically starts to spread, so it's advisable to regularly check your roses, particularly the lower leaves where it's commonly found. Rust manifests as orange or yellow spots on ...

Round black spots then appear on the rose leaves before they turn yellow and drop off ... fall victim to black spot disease. He said: "A spray composed of one part milk and two parts water ...