Cut off the black leaves and change the watering habit and move it. This should stop the fungus from spreading. However, if you see new black spots appearing you will need to spray it with a fungicide.

Your peace could have Phytophtora leaf spot which is a fungus that can attack Spathipyllum (peace lily). This is usually caused by environmental factor such as crowded situations where the sir can circulate or by over head watering where the foliage stays too damp. Leaf spot is diagnosed by visual confirmation of a black spot (lesion) that is not encircled by a yellow ring. This usually occurs on the top side of the leaf. If you have a case of leaf spot cut off the leaves with black spots and spray the plant with a fungicide. Your local nurdery & garden center will have a fungicide that you can use.

If you black spots are on the bottom side of the leaf, you could have an insect problem. If this is the case you will need an insecticide. You can tell if it is an insect by feeling the spot. If the spot is attached to the leaf instead of part of the leave you have scale (an insect).

You can cure both of these conditions and save the plant. To care for your peace lily read our Peace Lily Plant Care page.