Creeping Bellflower Response to Glyphosate and Synthetic Auxin Herbicides

Creeping bellflower ( Campanula rapunculoides ) is a difficult to manage weed commonly found in turfgrass and residential areas. We evaluated the efficacy of selected postemergence herbicides (glyphosate, dicamba, clopyralid, quinclorac, and triclopyr) on greenhouse-grown creeping bellflower. The experiment was conducted in Jan. 2016 and repeated in Sept. 2016. Each herbicide was applied at five rates plus a nontreated control. Clopyralid caused greater creeping bellflower biomass reduction and mortality than the other herbicides investigated. The herbicide dose required to cause 50% mortality was lowest for clopyralid [86–138 g·ha −1 acid equivalent (a.e.)] compared with dicamba (221–536 g·ha −1 a.e.), glyphosate (196–678 g·ha −1 a.e.), triclopyr (236–782 g·ha −1 a.e.), and quinclorac (>3000 g·ha −1 a.e.). Clopyralid could be an effective herbicide for managing creeping bellflower, although it is currently not registered for use in many habitats where this plant is a problematic weed.