We have a 3 ac. yard with 18 pecan trees, plus other things that would need to be trimed around, i have a 15 gal spray tank mounted on 1 of my mowers, about ever 3 or 4 weeks I use Round Up to trim it, i have been doing this for the pass 11 years, takes me about 1 hour to run around every thing, i never let it get over 1/2 in tall, so no brown stuff, after using a spray rig with a hand wand you will get to where you can spray a fine line, i trim my drive way like this, it kills about a 3 in wide strip