We tried using Zidua + Glyphosate in the fall, after planting wheat, where we have annual grass issues - like Annual Ryegrass or Roughstalk Bluegrass. I won't say it is perfect, but it has definitely helped.

There are products for post-emergence use in wheat. Powerflex is onecomes to mind; there are others. However, you need to be careful as to what you plant after the wheat.  These are specific as to what they will control. And I believe none of these will work on Perennial Ryegrass. So, you need to be sure what weed grass you are dealing with, in order to choose the correct product.  So,  I will say again... you need to be sure which weed grass you are dealing with first....