Steve - from what I winnowed through on reading up about this, looks like it can be spread via mites. It's a virus and it's horribly contagious, to the point of burning the field to rid of it any part of this. Yikes! I hope I never have to see this..
"A virus once again "fits" because virus particles are not limited to phloem and may be readily available within a range of plant tissue to hitch-hike on eriophyid mites. "
From this site:
http://bygl.osu.edu/content/tw...
