Old thread, I know, but...

I worked for Elanco the summer of '76 (field plot research intern) and my boss was a PhD crop physiologist & knew a LOT about what herbicides did & how they worked at the time--he was the guy the area reps called with questions.

He said Roundup sprayed in 7 gpa with at least 40 psi was a sweet spot for getting the best kill on anything.

This was almost a fog/mist; we weren't all using "drift reduction" spray tips & related technologies then. And like you say, the herbicide in contact with the leaves wasn't watered down as much as we generally do now.