Effect of saflufenacil mixed with various herbicides to manage Euphorbia esula and Linaria vulgaris

Leafy spurge ( Euphorbia esula L.) and yellow toadflax [ Linaria vulgaris (Mill.)] are pervasive weeds of pasture and rangeland in the Northern Great Plains. There are few effective herbicides to manage these species. Saflufenacil is a contact herbicide that is labeled to suppress perennial weeds when applied alone; however, saflufenacil + imazapic is labeled to effectively manage E. esula . While there is no currently publish data regarding the effectiveness of saflufenacil alone or in mixtures with various herbicides, mixing herbicides with different modes of action can increase management effectiveness. Therefore, mixtures containing saflufenacil and various herbicides may effectively manage E. esula and L. vulgaris . Experiments were conducted to determine the effectiveness of mixing commonly applied herbicides ( E. esula : imazapic and picloram; L. vulgaris : aminocyclopyrachlor and picloram) with saflufenacil to manage these weed species. Saflufenacil alone was the least effective on both species, as expected, due to the contact activity of the herbicide. Herbicide mixtures provided equal or greater responses (control estimates, height- and stem reductions) than the tested herbicides applied alone. Mixing saflufenacil with the tested herbicides resulted in additive control estimates, plant height-, and stem density reductions for both species one year after treatment. Stem density reductions for E. esula never exceeded 79%, while L. vulgaris stem reductions were as much as 90% with herbicides 1 year after treatment when compared with the nontreated. The results of these experiments suggest that saflufenacil could be mixed with commonly applied herbicides to increase the effectiveness of managing E. esula and L. vulgaris . However, additional management tactics will likely be necessary after one year to successfully further reduce the infestations of these weed species.