I’ve seen a number of wheat fields where the winter annuals are bigger than the wheat. One field in particular has been over run by blue grasss and the yield is going to reflect this. Most fields we are looking at received a treatment of Osprey, Harmony or both as early as November. We haven’t had to retreat but only a few acres.
If you have fields that look like the above (chickweed gone wild), I would document these fields so this doesn’t happen again (you know you now have winter annuals). I would consider any treatment now to be a rescue situation and would not expect adequate control.
While it is easier to make several treatments at once, usualy in March, it is rarely ever the right time to do so. Furthermore, some research has shown yield reductions when mixing nitrogen and herbicides. Check out this link: