Quinclorac is a selective postemergence herbicide with activity on both grasses and broadleaf weeds, including the problematic field bindweed, making it useful in systems with mixed weed populations. Field studies conducted from 2021 to 2022 in California, Michigan, New Jersey, New York, and Oregon assessed both crop safety and weed control efficacy for potential registration in grapes. Quinclorac was applied as a directed spray at 0.42 and 0.84 kg ai ha−1 at three timings: 90 d before harvest (Timing A), 60 d before harvest (Timing B), and post-harvest (Timing C). No grapevine injury was observed in California or Oregon. However, injury occurred in Michigan, New Jersey, and New York, with maximum ratings up to 32%, though severity varied by year and location. Mixed-effects modeling showed that cumulative rainfall and soil clay-plus-organic matter (COM) content explained 52% of the variation in injury (P < 0.001), with injury increasing as rainfall and COM content rose. Despite visible symptoms at some low-COM, high-rainfall sites, quinclorac had no significant effect on yield, berry size, or dormant pruning weights. Field bindweed control was consistently improved by quinclorac, particularly when a post-harvest application was included. Under the evaluated rates and timings, quinclorac posed an unacceptable risk of grapevine injury in many environments and is not currently suitable for use in grapes. Future work should focus on identifying management practices to mitigate the potential for injury.