Small, irregular spots on upper leaf surfaces are initially pale yellow in appearance, later becoming gray-brown with a yellowish margin. On the underside of the leaves, the spots have a gray, fuzzy appearance due to the presence of the pathogen. These fungal-like tufts are reproductive structures of the organism and their appearance is diagnostic for this disease. Symptoms frequently occur at low levels throughout the crop canopy. Early leaf spots are non-descript and are commonly confused with leaf spots and pustules caused by soybean rust.