With the advent of glyphosate-resistant (GR) weeds particularly Palmer amaranth pre applied herbicides have become critical once again for good weed control. After a Pre applied herbicide is used a number of outcomes can happen. The outcome we hope will happen is that the pre becomes activated and provides 3 to 5 weeks of residual Palmer control. Unfortunately, that does not occur every time. This session will discuss some of the latest research on pre applied herbicide usage in order to help producers and consultants make better decisions with this crucial aspect of weed control.