What is white spots on leaves?

White spots on the leaves of your Double Red Knock Out Rose are likely caused by powdery mildew, a common fungal disease. This can occur due to high humidity, poor air circulation, or excessive watering on the leaves. To manage this, ensure proper spacing between plants for better airflow, water at the base of the plant to keep leaves dry, and apply a fungicide specifically designed for powdery mildew if necessary. Regularly inspect and remove any affected leaves to prevent the spread of the fungus.