I have never experienced borer in a new planting before. The iris borer moth that lays the eggs on the plant is known to do that the previous Fall season or late Summer from what I have seen and they hatch in the following Spring. So, it is a little unusual to have borer on a Spring planting unless it was contaminated last year or perhaps this year by borers that hatched on a neighboring plant and were able to migrate. Did you see a borer?
If not, could it be soft rot? Are you familar with this?
K
