Absorption, translocation, metabolism, and spray retention of quinclorac inDigitaria sanguinalisandEleusine indica

Abstract

Absorption, translocation, and metabolism studies using 14C-quinclorac were conducted with quinclorac-sensitive Digitaria sanguinalis and quinclorac-tolerant Eleusine indica at the one- to two-tiller growth stage cultured under hydroponic conditions. After an 80-h exposure time, both species had absorbed nearly equal amounts of 14C-quinclorac (27 and 22% for D. sanguinalis and E. indica, respectively). Over the exposure period, the absorption curve for D. sanguinalis was curvilinear, with the maximum absorption occurring approximately 48 h after exposure. The response curve for E. indica was linear across the exposure period. Results from the translocation studies showed that 95% of the absorbed 14C-quinclorac remained in the treated leaf for D. sanguinalis after 80 h. However, only 58% of the absorbed 14C remained in the treated leaf of E. indica. Most of the 14C translocated out of the leaves moved to the tiller, the crown, and new leaf tissue. There was no appreciable exudation of 14C-quinclorac by either species during the absorption period. Results of the metabolism studies showed that neither the susceptible species (D. sanguinalis) nor the tolerant species (E. indica) metabolized the parent quinclorac herbicide. Spray retention studies showed that E. indica (tolerant) retained more applied quinclorac than D. sanguinalis (sensitive). Overall results suggested that a large difference in tolerance of the two species to quinclorac involves mechanisms other than absorption, metabolism, or spray retention.

Non-target-site glyphosate resistance inConyza bonariensisis based on modified subcellular distribution of the herbicide

“…Numerous studies have examined GR mechanisms of both CC and CB (see the recent review by Sammons and Gaines). As for any herbicide, a non‐target mechanism for glyphosate resistance could stem from modifications of plant traits involving any point along the pathway, from leaf retention through penetration, translocation and arrival at the target site . A change in the target‐site enzyme or its activity would be a target‐site resistance mechanism (TSR) .…”

Quinclorac: Soil Behavior and Foliar vs. Root Absorption by Torpedograss (Panicum repens)

“…Quinclorac is a substituted quinolinecarboxylic acid, a class of highly selective auxin herbicides. Reviews on the mode of action and basis of selectivity are available elsewhere (Grossman 1998;Grossman and Kwiatkowski 2000;Grossman and Scheltrup 1998;Koo et al 1994;Zawierucha and Penner 2000). Mode of action and associated symptomatology varies between grass and broadleaf species.…”

“…Conversely, typical auxin-type herbicide symptoms occur in sensitive broadleaf species. Foliar absorption of quinclorac by target species has been quantified by several authors, however, results have been variable (Chism et al 1991;Grossman and Scheltrup 1998;Zawierucha and Penner 2000). Chism et al (1991) reported that within 0.5 h of foliar application, 85 and 66% of the amount applied was absorbed by southern crabgrass [Digitaria ciliaris (Retz.)…”

Quinclorac Absorption and Translocation Characteristics in Quinclorac- and Propanil-resistant and -susceptible Barnyardgrass (Echinochloa Crus-galli) Biotypes

“…], a susceptible species, nor in goosegrass [Eleusine indica (L.) Gaertn. ], a resistant species (Zawierucha and Penner 2000). Although some metabolism of quinclorac may occur in monocots, metabolism is generally low and does not appear to influence resistance.…”