Wounded rhizomes are easily attacked by this bacterium which results in a foul-smelling decay of the rhizomes. Removal and burning of dead leaves in the fall will eliminate a number of the iris borer eggs. Larvae can also be killed by hand in June bye squeezing infested leaves in the vicinity of the injury. During division, rotted and heavily infested rhizomes should be discarded. Borers in lightly infested rhizomes can be killed by poking them with a piece of wire.
Chemical control can also be effective.
Start spraying when growth first starts until about June 1. Normally, two applications are needed. University of Nebraska Cooperative Extension 2.