| I don't grow Lousiana Iris so don't know if they can be saved. When you see bearded iris damaged by iris borer you should dig them up and trim away damaged leaves and/or rhizome parts (and squish any borers you find!). They say not to compost that cut away stuff so as not to continue the spread of borers. Anyway, what's still ok can be replanted. They recommend cleaning them before replanting with a 5% or 10% solution of clorox and water, but I don't bother with that. They'll survive. Even if you don't dig them up! You'll detect the occasional rotted rhizome if left, but otherwise the damage is done. The way borers work is: they're little white moths in summer... they lay their eggs in the debris around iris in late summer/autumn and the eggs overwinter there. In spring they hatch and the tiny larvae climb the leaves, make a pinpoint hole, and burrow inside. They spend the spring and early summer eating their way down through the leave, enter the rhizome, then pupate. They are large white/pink larvae inside the rhizome -- sort of pretty, really. :) Then they hatch into small white moths -- around August here. Then the process starts again. :) The best prevention is to clean the debris from around your iris in autumn. It cleans up their eggs and leaves them with no protection for the winter. I had them last year for the first time in many years. blech. :( | 
