Once in the rhizomes, the bacterial rot progresses rapidly. The characteristic foul odor is one of the most diagnostic symptoms. The most effective control of this disease focuses on control of the iris borer. Additionally, setting the rhizomes shallow is helpful since this permits the sun to get to part of the rhizome. Crowded or shaded situations should be avoided since they are conducive to development of soft rot.
Sanitation is also very important.
Cleaning up all plant debris on which the borer eggs overwinter in the fall or very early spring will cut down materially on borers. Leaves with early symptoms of disease can be cut well below the water-soaked areas and must be done before the bacteria reach the rhizome. Leaf spot, Xanthomonas . Symptoms appear as translucent, irregular spots on the leaves. These are dark green and water-soaked during wet weather.