Biologically effective dose of pyraflufen-ethyl/2, 4-D, applied preplant alone or mixed with metribuzin on glyphosate-resistant horseweed in soybean. (21st October 2021)

• Record Type: Journal Article
• Authors: Westerveld, David B.; Soltani, Nader; Hooker, David C.; Robinson, Darren E.; Sikkema, Peter H.
• Is Part Of: Weed technology. Volume 35:Number 5(2021)
• Page Start: 824
• Page End: 829
• Publication Date: 2021-10-21
• Subjects: 2, 4-D -- metribuzin -- pyraflufen-ethyl -- horseweed -- Conyza canadensis (L.) Cronq. -- soybean -- Glycine max (L.) Merr; Canada fleabane -- glyphosate resistance -- distribution -- multiple-resistant -- preplant application -- visible control; Weeds -- Periodicals; Weeds -- Control -- Periodicals; 632.5
• DOI: 10.1017/wet.2021.46
• Languages: English
• ISSNs: 0890-037X

Abstract

Abstract: Glyphosate resistance in weed species has presented immense challenges for farmers in Ontario. The co-application of burndown plus residual herbicides provides control of glyphosate-resistant (GR) horseweed in soybean. Pyraflufen-ethyl/2, 4-D is a premixed herbicide formulation sold under the tradename Blackhawk ® . Five field experiments were conducted over a 2-yr period (2019, 2020) in fields in southwestern Ontario to ascertain the biologically effective dose of pyraflufen-ethyl/2, 4-D, applied alone, or mixed with metribuzin, for GR horseweed control when applied preplant to soybean. Soybean visible injury for all treatments was <15%. At 8 wk after application (WAA), the calculated doses of pyraflufen-ethyl/2, 4-D for 50%, 80%, and 95% control of GR horseweed were 390, 1, 148, and >2, 108 g ha −1, respectively. The addition of metribuzin to pyraflufen-ethyl/2, 4-D reduced the doses of pyraflufen-ethyl/2, 4-D for 50%, 80%, and 95% control of GR horseweed to 19, 46, and 201 g ha −1, respectively. Pyraflufen-ethyl/2, 4-D + metribuzin controlled GR horseweed by 97%, which is comparable to the current industry standards. Based on these results, pyraflufen-ethyl/2, 4-D + metribuzin (527 + 400 g ha −1 ) applied preplant can be used for GR horseweed control in soybean.