"That's interesting about "roundup-tollerant" seed."

If you think that's cool, science has done even better. There are
seeds available for crops like soybeans and cotton that are very
resistant or immune to Round Up, so that it can then be used to control
weeds. Here you have a chemical that we all are used to see killing
just about anything, and now you have crops that can be routinely
sprayed with it. The grass seeds that I know of are not genetically
modified, they have been developed from varieites that had natural
Round Up resistance. Hence, I don't think it's quite as effective, but
the idea is the same and it apparently works.