Generally, however, symptoms caused by fungi can be separated from those associated with bacterial streak, based on the presence of spore-producing structures and spores in the fungal incited lesions. Beards of bearded varieties can also be affected. Grain is usually not destroyed, but it may be brown and shriveled. Yield effects are most pronounced when the bacteria invade the stem, usually just below the head and in upper joints. It cannot infect wheat tissue directly, so it must enter plants via natural openings in plant structures or in sites wounded by freeze damage or insect feeding.
Free water is necessary for the bacterium to enter wheat tissue.
As a result, symptoms of the disease usually appear after several days of damp, rainy weather. Best results can be obtained by using only certified seed and allowing 2 years between wheat crops in a field. Also, do not rotate wheat with barley as the bacterium will be maintained in the field at high levels. Current research has indicated varying degrees of susceptibility for different varieties. However, this information is not sufficiently developed to be used as a reliable control measure.