Bacterial Pustule, although common in most soybean production areas, is of minor importance because of the high level Of resistance to the pathogen in many commercially available cultivars. The bacterium overwinters in infected crop residue, in seeds and on the roots of wheat and some weeds. Consequently, new infections occur whenever wet conditions prevail. Later in the center of the spots a small, raised pustule develops which is most noticeable on the lower leaf surface. Pustule formation and the absence of a water soaked appearance in the early stages of lesion development distinguish bacterial pestle from bacterial blight.
Diseased leaves develop a tattered appearance as dead tissue is torn away because of weathering.
Severe infection often causes some defoliation of young leaves which are more susceptible than older leaves. Controls are the same as those suggested for bacterial blight. Resistant cultivars exist and should be planted. Wildfire bacteria overwinter in infected crop residue and seed. The ability of the bacteria to overwinter is reduced in areas with considerable seasonal temperature fluctuations.