Common name of fungal leaf spot. Black spot attacks the foliage of plants such as roses. There is usually a yellow halo around the dark spot. Entire leaves then turn yellow and ultimately die. Best controls include selection of resistant plants and Garrett Juice plus garlic tea and diluted milk. Keep bare soil mulched. Apply cornmeal to the soil or cornmeal juice to the foliage. BioWash (to clean plants) is the best commercial product. BioSafe is the commercial product labeled for this treatment.