Barrier application for cutworm control in vineyards requires an efficient target recognition system and a rapid and precise sprayer control system to ensure an adequate coverage on grape trunks and posts that effectively repels climbing cutworms. In response to grape growers request for a simplified trailer sprayer, this research developed and tested an automated targeted sprayer system consisting of a computer-controlled scanning laser based trunk detection system and a multi-nozzle sprayer control system installed on a commercially available, low-cost trailer sprayer platform. The sprayer system consists of two arrays, one on each side, with three nozzles connected to solenoids wired to a CAN bus control system. An existing trunk detection system was modified to improve the accuracy of the target recognition by increasing the speed of the scanning laser from 10 to 40 Hz and adding a revised trunk size compensation function. Preliminary tests in a simulated vineyard showed that the trunk size estimated by the target recognition system decreased with increasing travel speed but improved with a compensation function derived from experimental tests. The laser failed to detect small trunks beginning at 1.34 m s-1, indicating that a laser scanner with an update rate >40 Hz may improve the trunk detection accuracy. Spray efficiency tests showed that targeted applications applied higher application densities than commercial applications at <10% of the spray volume, with about 65% to 70% of the spray hitting the target under the environmental conditions tested. The trailer-based targeted sprayer for cutworm control would greatly reduce insecticide application costs and open up opportunities for alternative control products that are more desirable but prohibitively expensive in larger application volumes used in conventional application systems.