Nose-picking, how to make it stop?

LSU628

DD has become obsessed lately with picking her nose. It has become almost a comfort thing (she does it riding in the car, before falling asleep). The weird thing is she gets SO angry when I tell her to stop picking her nose, that it is not a nice/polite thing to do. A few weeks back she was picking it to the point where it was bleeding. I've tried telling her that she will give her nose a "bo-bo", that she will get germs in her nose (they talk about germs and handwashing a lot at school) but she persists. It seriously grosses me out, especially when she wants to hand me the boogers that she has picked. GAG!! Any suggestions on ways to break the not-so-nice habit?