White leaf spot in October
This resembles a fungal pathogen. It could be powdery mildew or leaf spot. More than likely, its mostly cosmetic, but I would suggest taking a sample to your Extension Office to further diagnose the cause through our Plant Health Clinic. You will receive a report that will contain a recommendation on cultural controls and possibly a treatment to prevent in the future. I would be careful of overwatering and over-head watering in the container. With as wet as it has been this year, many plant diseases are more likely with the wet conditions.