Dr. Alicyn Smart Plant Pathologist & Director of the Plant Disease Diagnostic Laboratory at University of Maine Cooperative Extension. The fungus is turning those lawns a startling shade of black and has homeowners calling plant experts looking for solutions. Unfortunately, there are none. What people are seeing are the black spores of the pathogen Cladosporium creating a condition known as black lawn. And according to Smart, any part of a lawn that the spores turned black was an area already in trouble.