The speckles are fungal fruiting bodies that produce spores. These spores can be used to differentiate the two species in the lab. As lesions expand and grow together, the whole head may become dark brown. Lesions on the awns may give a brown and green banding symptom which is fairly characteristic. Black chaff is often confused with glume blotch.
Black chaff is the only other disease that often causes awn banding like glume blotch.
Lesions eventually turn brown or black and may be covered with drops of yellow bacterial exudate. It can be diagnosed fairly easily in the lab by looking for bacteria streaming from lesions. There are no black or brown speckles as with glume blotch. Black chaff is rare in Kansas. Genetic melanism, or head browning, also can be confused with glume blotch.