The recent heavy rainfall favors the development of several diseases in wheat and melanism which can easily be mistaken for disease. Melanism, a genetically controlled discoloration, is often confused with black chaff. Black chaff is a bacterial disease that affects the glumes of developing wheat heads. Symptoms consist of dark lines or patches on glumes and dark lesions on the awns. The lesions often result in alternating green and brown areas on the awns which aids in identifying the disease.
Black strips are also diagnostic of black chaff.
Leaf symptoms are dark water soaked longitudinal streaks that result in tan or brown dead tissue. Melanism, or false black chaff, produces dark purple to black streaks or blotches on the glumes. This dark discoloration is usually more uniform than black chaff. The awns and peduncle show no symptoms. The formation of a dark purple to purple brown ring at each joint is indicative of melanism and can be used to diagnose this disorder.