The preferential accumulation of picloram at sites of active growth in gorse ( Ulex europaeus L.)

Greenhouse and laboratory studies were conducted to determine the effect of atrazine on efficacy, absorption, translocation, and metabolism of primisulfuron applied to velvetleaf and giant foxtail. Efficacy of primisulfuron was reduced by 18 and 22% when applied at 20 and 40 g ai ha−1, respectively, in combination with 1.7 kg ai ha−1atrazine to velvetleaf. Efficacy of primisulfuron was reduced by 15 and 16% when applied at 30 or 60 g ai ha−1, respectively, in combination with 1.7 kg ai ha−1atrazine to giant foxtail. Foliar absorption of14C-primisulfuron by either weed species was not affected by addition of atrazine to the treatment solution. Atrazine had no effect on metabolism of14C-primisulfuron by either weed species. In the absence of atrazine, translocation of absorbed14C from primisulfuron out of treated leaves of velvetleaf and giant foxtail averaged 19 and 29%, respectively, across sampling times. These values were reduced to an average of 9 and 16% in velvetleaf and giant foxtail, respectively, when14C-primisulfuron was applied in combination with atrazine. The majority of translocated14C from primisulfuron was transported acropetally in velvetleaf and basipetally in giant foxtail. Atrazine significantly reduced14C translocation from primisulfuron to these meristematic sinks in both weed species. Reduced translocation was positively correlated with reduced control of these weeds when primisulfuron was tank mixed with atrazine.

Section: Resultsmentioning

confidence: 99%

“…TLC plates were developed in a solvent system of methanol: benzene (2:1 by vol). Radioactive spots were located and Rf values recorded with a radioactive plate scanner 11 . The radioactive spots were then removed and radioassayed by liquid scintillation spectrometry.…”

Section: Methodsmentioning

confidence: 99%

Atrazine Reduces Primisulfuron Transport to Meristems of Giant Foxtail (Setaria faberi) and Velvetleaf (Abutilon theophrasti)

Hart

Penner

1993

“…act. 79.6 MBq^mmole -1 ) was dissolved in 10% (v/v) aqueous ethanol containing 0.5% (v/v) oxysorbic (20 POE) 6 (polyoxyethylene sorbitan monolaurate). The concentration of both herbicides was approximately 940 Bq/10 jul solution.…”

Section: Methodsmentioning

confidence: 99%

Absorption, Translocation, and Foliar Activity of Clopyralid and Chlorsulfuron in Canada Thistle (Cirsium arvense) and Perennial Sowthistle (Sonchus arvensis)

Devine

Born

1985

Both14C-clopyralid (3,6-dichloropicolinic acid) and14C-chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzensulfonamide} were readily absorbed by Canada thistle [Cirsium arvense(L.) Scop. ♯ CIRAR] leaves, with 99 and 75%, respectively, of the applied doses absorbed 144 h after application. Absorbed14C-clopyralid was rapidly exported from the treated leaves, whereas14C-chlorsulfuron was translocated much more slowly. After 144 h, 29% of the applied14C-clopyralid and 5% of the applied14C-chlorsulfuron were recovered in the roots and developing root buds of Canada thistle plants. Smaller amounts of the two herbicides were absorbed and translocated in perennial sowthistle (Sonchus arvensisL. ♯ SONAR) than in Canada thistle. More14C-clopyralid than14C-chlorsulfuron was absorbed and translocated out of treated leaves of perennial sowthistle, but equal amounts, 3 to 4% of the applied doses, were recovered in the roots and root buds 144 h after application. Foliar applications of clopyralid, followed by removal of the treated shoot 24, 72, or 144 h after application, markedly reduced shoot regrowth in both Canada thistle and perennial sowthistle. Similar treatment with chlorsulfuron did not prevent shoot regrowth in either species.

“…The active growth sites of developing annual weed seedlings are shoot apical meristems and developing immature leaves (Raven et al 1986). Accumulation in the active growth sites has been documented for herbicides that are translocated primarily in the phloem (Claus and Behrens 1976;Devine et al 1983;Devine and Vanden Born 1985;Field and Thai 1980). Movement of a herbicide in a grass plant to the shoot region above the treated leaf requires initial basipetal movement of the herbicide to the crown meristematic tissue of the grass plant, suggesting phloem mobility for isoxa8utole applications to giant foxtail.…”

Section: C Translocationmentioning

confidence: 99%

Optimizing foliar activity of isoxaflutole on giant foxtail (Setaria faberi) with various adjuvants

Young

Hart

1998

Greenhouse, laboratory, and field studies were conducted to evaluate the potential of nonionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO), and 28% urea ammonium nitrate (UAN) to enhance whole plant efficacy, absorption, and spray retention of foliar applications of isoxaflutole to giant foxtail. In greenhouse studies, isoxaflutole at 10 g ai ha−1reduced giant foxtail growth 5%, whereas the addition of a spray adjuvant reduced giant foxtail growth at least 75%. The addition of UAN improved giant foxtail growth reduction when used in combination with isoxaflutole plus NIS. Isoxaflutole spray retention on the leaf surface was increased with an adjuvant and a further increase was observed with the addition of UAN. Isoxaflutole applied with NIS, COC, and MSO resulted in 42, 60, and 91%14C absorption, respectively, compared to 21% absorption from isoxaflutole applied alone 24 h after treatment (HAT). Increased14C absorption and entry into the cuticle when an adjuvant was utilized with isoxaflutole resulted in greater translocation of14C from isoxaflutole out of the treated leaf. Significant basipetal movement from foliar applications of14C-isoxaflutole suggests phloem mobility. In field studies, isoxaflutole applied with MSO provided greater giant foxtail growth reduction compared to isoxaflutole applied with NIS and in some cases COC. The addition of UAN to isoxaflutole did not increase whole plant efficacy in field studies. These studies indicate isoxaflutole has excellent potential to be used for control of existing giant foxtail present at the time of corn planting if an adequate adjuvant is utilized.