Mark VanGessel, Extension Weed Specialist; firstname.lastname@example.org
A number of glyphosate products such as Roundup and Touchdown are labeled as harvest aids for winter wheat and barley (but not malting 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. 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. Be aware of the replant interval for 2,4-D as well.
I am not aware of any paraquat formulation labeled as harvest aid for small grains.