During the season, it is my preference to keep the turf underneath the trellis clear of weeds. I maintain 1.5 feet on each side clear of grass and weeds. In order to do this, I spray both a premergent and round-up on the ground to kill any weeds and hopefully prevent any from growing. The premergent that I use is Treflan, most commonly labeled as Preen. I buy this chemical in bulk in liquid form I use a 20 gallon spot sprayer with a funnel that was installed to prevent drift of the the spray while going down the rows and on a windy day.
This funnel was purchased at Tractor Supply store and bent to a good shape for spraying. By removing the end nozzle you can slide the funnel over the end and then reinstall the end nozzle.
Also I bought a new wand that is 30" long so that I don't have to lend over as much while doing this from the tractor.