So, I'm not really sure why a posting on sugar beets makes it onto /. anyway, but I'll cast in a couple important points for civil discussion.
1) The pollen from sugar beets does travel a very long distance (Darmency, H. et al., 2009. Pollen dispersal in sugar beet production fields. TAG Theoretical and Applied Genetics, 118(6), 1083-1092).
2) This is may be an environmental concern, but it is also a concern for anyone growing sugar beets. That is, there are problems controlling weedy beets when herbicide-resistant beets sprout up.
3) This entire issue is unimportant when beet growers cultivate off the tops of their beets, rendering them sterile. If they receive a higher yield for the herbicide usage, this may be an extra drive across the field may be a good option for preserving the integrity of the resistance trait.