BLACK SPOT: 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 skim milk. Apply cornmeal to the soil or cornmeal juice to the foliage.  Plant Wash is my favorite commercial product.  It works great!