Leaves turn brown and black and then fall. Cuttings may rot at base but roots develop above the rot. These plants often die after potting. Rhododendron - Stem and crown cankers form. Root and stem cankers develop.
Leaves fall even if only one or a very few spots form.
Twig dieback occurs if defoliation is severe. Brown to black leaf spots have yellow halos. Spathiphyllum - Older foliage wilts and yellows. Roots die allowing the plant to be easily removed from the soil. Sunken black spots form at the base of petioles.