Knock Out Roses Yellow Leaves

Question

We have several Knock Out roses. They have some new growth but the old growth has yellowing leaves with black spots on them. What is this and is it a common problem? What should we do to remedy and keep it from reoccurring? Thank you!

Answer 1

This article should help: https://www.gardeningknowhow.com/ornamental/flowers/roses/yellow-rose-leaves.htm

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