Black chaff Black chaff causes dark-brown or black lesions on the glumes of infected wheat heads. The stem below the head and the awns also can be infected. Infected awns often have alternating bands of diseased and healthy green tissue. The bacteria that cause black chaff also cause bacterial streak on leaves. Black chaff is often confused with Stagonospora nodorum blotch on heads or a physiological disorder of the plant known as “pseudo-black chaff.”
