Diflufenzopyr Influences Leafy Spurge (Euphorbia esula) and Canada Thistle (Cirsium arvense) Control by Herbicides

Abstract

Diflufenzopyr is an auxin-transport inhibitor that has increased broadleaf weed control by some auxin herbicides. The effects of auxin herbicides when applied with diflufenzopyr for leafy spurge or Canada thistle control, herbage production, and herbicide absorption and translocation in leafy spurge were evaluated. The influence of diflufenzopyr on leafy spurge and Canada thistle control varied by herbicide. Diflufenzopyr applied with quinclorac increased both Canada thistle and leafy spurge control. Diflufenzopyr added to picloram increased leafy spurge but not Canada thistle control, whereas control of both weeds generally increased when diflufenzopyr was applied with dicamba. Canada thistle control slightly improved when diflufenzopyr was applied with clopyralid or clopyralid plus 2,4-D compared with the herbicides alone. Diflufenzopyr did not influence weed control from imazapic and reduced weed control from glyphosate. Weed control was not influenced by the ratio of diflufenzopyr to herbicide or by whether diflufenzopyr was tank mixed with or applied before the herbicides. Diflufenzopyr did not affect cool-season grass production in the greenhouse or field but did reduce sideoats grama and switchgrass production when applied alone and with dicamba in greenhouse trials.14C-picloram and14C-quinclorac absorption was increased when applied with diflufenzopyr in leafy spurge but nearly all absorbed herbicide remained in the treated leaf compared with the herbicides applied alone.14C-dicamba absorption decreased from 60 to 14% when applied with diflufenzopyr and translocation to the roots decreased by a factor of 10. Overall, the increase in weed control from the addition of diflufenzopyr was much more pronounced with leafy spurge than with Canada thistle.

Canada Thistle (Cirsium arvense) Control with Aminopyralid in Range, Pasture, and Noncrop Areas

“…Dicamba applied at 1.12 kg/ha did not control Canada thistle 1 YAT (Beck 1988;Beck et al 1989). Our results with dicamba + diflufenzopyr (0.28 + 0.11 kg ai/ha) were somewhat different than those of Lym and Diebert (2005). Canada thistle control 12 months after June application was only 11%, whereas our results for five locations averaged 58% control 1 YAT across spring and fall timings.…”

“…Bultsma et al (1992) found clopyralid + 2,4-D amine applied at 0.21 + 1.1 kg ai/ha to Canada thistle in the bolting stage provided 63 to 65% control approximately 1 YAT. Lym and Diebert (2005) found clopyralid applied at 0.28 kg /ha provided 56% control 12 months after a June application, whereas Beck et al (1989) reported that clopyralid applied at 0.28 kg ai/ha in the spring when Canada thistle was in the rosette stage provided only 24% control 1 YAT. Beck (1988) found clopyralid applied at 0.28 and 0.56 kg ai/ha to bolting plants provided 30 and 63% control 1 YAT, respectively.…”

Control of Photosystem II– and 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor–Resistant Palmer Amaranth (Amaranthus palmeri) in Conventional Corn

“…In addition, Schuster and Smeda (2007) reported >95% common waterhemp control with a 35 DAPOST application of dicamba plus diflufenzopyr. Previous studies have reported increased weed control by tank-mixing diflufenzopyr with dicamba; however, the synergistic effect was species-specific (Grossmann et al 2002; Lym and Deibert 2005; Wehtje 2008). There is no published evidence of the synergistic effects of dicamba and diflufenzopyr for Palmer amaranth control.…”

Time of Application Influences Translocation of Auxinic Herbicides in Palmer Amaranth (Amaranthus palmeri)

“…Diflufenzopyr (DFFP), a synthetic semicarbazone, is combined with dicamba in the product Distinct ® for use in corn, pastures, and rangeland and blocks movement of both natural plant auxins and dicamba (Anonymous 2015a). It has been suggested that DFFP may improve herbicide efficacy by limiting translocation to growing points and meristematic tissue, thereby reducing regrowth following herbicide application (Bowe et al 1999; Lym and Deibert 2005). This takes place presumably through inhibition of PIN proteins via binding to proteins known to interact with the phytotropin naphthylphthalamic acid, itself an auxin transport inhibitor (Brunn et al 1994; Grossmann et al 2002; Hess et al 1998; Subramanian et al 1997).…”