Welllllllllllllllllllll, I have terrible rust on my garlics >:(, and did a sample dig and it did seem to only be cosmetic, however, on one row inparticular, it has gotten so bad that the plants were begining to get really sick and some had keeled over. Today I dug them up, they are okay, not huge, but fine for us, and the rust does stop at soil level. My onions are all totally unaffected.