It is likely a combination of factors making your Chelone look bedraggled. There is minor leaf spot disease low on the plant but it is not of concern.
This late in the season it is pretty common to see many plants with tired, spotty or drying leaves. It is not worrisome and they should flush new, healthy foliage next spring.
This particular native plant wants moist or even wet growing conditions as their natural habitat is woods, streambanks and swamps.
More about them here: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=287079&ispro...;