From Weekly Crop Update
Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
A few phone calls have come in about treating weeds in winter wheat. First, a lot of the wheat is getting to a stage where it would be injured with some of the herbicides. Also, many of the weeds are probably too large for effective control. Finally, the wheat is getting large enough that it will intercept a lot of the herbicide spray, so will you get the spray coverage you need. Each field needs to be evaluated on a case by case basis to determine if a spray should be made.
Source: Weekly Crop Update