It's still out there, I bought some last year. Bought it at the local coop. Barricade does the same thing and is easier to find.You find any surflan let me know. It hasn’t been available for several years. I was told the plant burned down. Damn if I know, but I do know it would kill grass/sand burs in a single application.
https://www.seedranch.com/Surflan-A-S-Pre-Emergent-Herbicide-1-Gallon-p/surflan-as-1-gallon.htm