rusty onions

a plot near to me has what im told is rusty onions,,,,there colour is a rusty orange,,,,does this spread

I'm getting something similar on my softneck garlic. Funnily enough, it doesn't seem to be affecting the hardneck types.

Rusts are usually specific to one plant and will not spread to other species i.e. onion rust will not spread to leeks, leek rust will not spread to onions. If you get rust regularly it is well worth looking in the catalogues for rust resistent varieties.