Leaf spots are round blemishes found on the leaves of many species of plants, mostly caused by parasitic fungi or bacteria.
A typical spot is "zonal", meaning it has a definite edge and often has a darker border. When lots of spots are present, they can grow together and become a blight or a blotch. Fungal spots are usually round or free-form in shape.
In most cases, leaf spots are considered to be only a cosmetic problem, but they can have economic effects on nurseries or in floriculture.