I hear BT works and it is non-toxic to most creatures. It prevents caterpillar larvae from developing.

Why do you have to dig them up? Can't you just clean up the dead leaves and squish each fan as it grows? We don't have the borer here, so I'm curious.

Renee

I dig them up to cut off the infected parts and soak them to kill the larvae. I do clean up the dead leaves in the fall but it doesn't seem to help much. I didn't think BT would work because I thought it had to come in contact with the worms? Have to check into that, thanks. You're lucky not to have them. Marg

What is BT?

BT is Bacillus Thurengiensis (spelling) otherwise known as an organic pesticide.

It does not have to contact the borer- the borer eats the leaf it has been sprayed on and its guts bust open. I use it for budworms. It takes a while for it to reduce the population, and there is still some damage, but nothing like before. I read about using it for borers on an iris society page, but I can't remember which one now.
Renee

Thanks Renee. That's good news. I'll have to try it. Today it's very windy here so I think I'll have to wait for a calmer day to spray. Everything I had heard about BT before said it had to come in contact with the worms to be effective. Marg