Chelone Leaves with Brown Spots
Hi and thanks for contacting AaE. This is probably a bacterial leaf spot disease. Without some lab work it would be hard to identify just which bacteria is at work here.
Nevertheless, control methods are the same:
Remove the affected leaves, avoid overhead watering, thin the plants to increase air circulation, and maintain good sanitation under the plants by removing leaf litter and other debris. Here is a link that talks about leaf spot diseases on many plants: