Studies were conducted under greenhouse conditions at Michigan State University and Texas Tech University to investigate the tolerance of Miscanthus × giganteus and Miscanthus sinensis to POST herbicides. Miscanthus sinensis and M. × giganteus were treated with 10 and 18 POST herbicide treatments, respectively. Plants were evaluated for injury as well as dry aboveground and belowground biomass production 28 days after treatment. Imazethapyr at 0.069 kg ai ha⁻¹ caused 5% injury to M. sinensis, which was greater than the nontreated check. Imazethapyr, imazamox at 0.044 kg ai ha⁻¹, and rimsulfuron at 0.017 kg ai ha⁻¹ reduced aboveground biomass of M. sinensis compared with the nontreated check. Dicamba at 0.56 kg ai ha⁻¹ and halosulfuron at 0.035 kg ai ha⁻¹ resulted in M. sinensis aboveground biomass similar to the nontreated check. Injury exhibited by M. × giganteus was greater than the nontreated check with glyphosate at 0.84 kg ae ha⁻¹ (54%), foramsulfuron at 0.037 kg ai ha⁻¹ (32%), nicosulfuron at 0.035 kg ai ha⁻¹ (28%), and imazamox at 0.044 kg ai ha⁻¹ (10%). These treatments also yielded the lowest aboveground biomass values. The results of this study demonstrate that M. sinensis is more tolerant of the POST herbicides tested here than M.×x. giganteus. Several herbicide options may be available for weed management in M. sinensis and M. × giganteus stands following additional field trials to validate initial findings.

Nomenclature: Aminopyralid; dicamba; foramsulfuron; glyphosate; halosulfuron; imazamox; imazethapyr; nicosulfuron; rimsulfuron; Miscanthus sinensis; Miscanthus × giganteus.