Mark VanGessel, Extension Weed Specialist; email@example.com
A number of glyphosate products such as Roundup and Touchdown are labeled as harvest aids for winter wheat and barley. Check the label of other formulations of glyphosate to be sure the product you use is labeled as a harvest aid. Applications must be made after the hard-dough stage and at least 7 days prior to harvest. Aim is labeled as well, but the spectrum of control is limited to velvetleaf, morningglory, pigweeds, and few other weeds. Apply at least 3 days before harvest. Use of 2,4-D (or products containing 2,4-D) is generally not recommended as a harvest aid due to its volatility, and potential damage to the crop during application.
I am not aware of any paraquat formulation labeled as harvest aid for small grains.