They spray potatoes to kill the plants before harvest. Once they are dead and dry, they begin to harvest.
Thats one thing I never did. Work on a potato farm back in the day shoveling spuds into the grader. Lots of my school friends did though. Now days, they wouldnt allow kids to do menial work like that. Its demeaning you know...HA!
But I did clean barn on our small farm and went out with my dad and brothers peeling popple pulpwood though. Three cents a stick. 300 sticks a day..7 days a week until the bark started to stick.
sulfuric acid is the desiccant spray of choice for potatoes.
However, 70 other crops get the pre-harvest glyphosate.