I would suspect your lilies most likely have a leaf spot disease cause by a fungus or edema. If fungal, those spots could grow together forming larger damaged areas. If edema, that is a water issue. they can become quite pot bound and actually stop water from draining out of the container. If so, consider re-potting with new media and removal of those circling roots. water carefully. Better to be slightly on the dry side than over waterd
