Not every woodlot owner has a John Deere "Gator" with a spray rig. If you don't, you can hire Brooks and Christie Forestry or other forestry service companies to conduct the spraying for you.
Spraying should be in a somewhat narrow band centered on the row of trees. Perhaps 20 to 22 inches wide. This leaves a wide swath of grass/weeds between the rows. The upside to this thick band is that it keeps drying winds away from the seedlings. The downside is that the thick grass/weed band is a perfect habitat for mice and voles.
Richwood Timber LLC
richwoodtimberllc (at) w9fz.com