go to the feed store and ask for the best rat poison bait they have. These are a sort of "food cube" which should work. I'd put several of these in an open can or something which can keep them dry enough to be palatable, but allow entrance to the bait. Should do the trick. Perhaps using hardware cloth over the corms would help exclude most rodents. It's tough when you have to kill wildlife, but sometimes that's the way it goes.

harware cloth?? what is it and where can i get some?? got major probelms with something eating stems to the ground...just nawing them into.

You can get hardware cloth at hardware and building supply stores. It is basically wire mesh. Since hardware cloth has holes large enough to allow a mouse to squeeze through, you may have to line it with wire window screening.