If you miss the rosette stage, a spade is the only choice and you may have to haul the plants off the field to prevent seeding. You just aren't going to prevent seed production after the plant bolts. Some of you are probably seeing white or yellow blooms in your forages. But they aren't forages. Anything blooming now is either a perennial or winter annual and there is nothing you are going to do to stop seed development.
Weeds recognize opportunities but are usually poor competitors with established plants.
So if you've got the weed, I'd say you didn't have a good stand at some time. The white ones could also be a mustard. Food move ment will also carry the herbicide to the roots. Spring spraying usually isn't as effective even though they curl up causing us to think we did a good job. Mustards are winter annuals, sprout ing in the fall, and competition is the best pre ventative and control.