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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #303065
Title: Absorption and fate of aminocyclopyrachlor in bermudagrass, bahiagrass, cogongrass, and tall fescue

Author
item PARKER, E - Auburn University
item WEHTJE, G - Auburn University
item MCELROY, J - Auburn University
item Price, Andrew
item MCCULLOUGH, P - Auburn University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2014
Publication Date: 2/28/2014
Citation: Parker, E.T., Wehtje, G.R., Mcelroy, J.S., Price, A.J., Mccullough, P.M. 2014. Absorption and fate of aminocyclopyrachlor in bermudagrass, bahiagrass, cogongrass, and tall fescue. Southern Weed Science Society. CDROM.

Interpretive Summary:

Technical Abstract: Aminocyclopyrachlor (ACPC) is a synthetic auxin herbicide that controls broadleaf weeds in tolerant graminaceous species. Little is known about the fate of ACPC applied at labeled rates in graminaceous species. Studies were performed to evaluate ACPC foliar uptake, translocation, and metabolism using radiolabeled ACPC in the following species listed from most to least tolerant: tall fescue, bermudagrass, bahiagrass, and cogongrass. 14C radiolabeled ACPC was applied as a single 10µL drop totaling approximately 22,000 disintegrations per minute to the adaxial side of a fully mature leaf. Plants were harvested at 1, 2, 4 and 8 days after treatment (DAT) and separated into target area, treated leaf, remainder foliage and crown plus roots. Metabolism studies were conducted in a similar fashion except two 10µ drops totaling approximately 336,000 DPM were applied to two separate leaves. Harvest intervals were changed to 7 and 14 DAT to allow adequate time for metabolism to occur. Plants were divided into target area and remainder foliage to prevent interference of unabsorbed herbicide in data analysis. Plant parts were homogenized then solutions were placed onto silica-gel chromatography plates and scanned for metabolites. Only peaks of 5% or greater of total radiation recovered were considered significant. Data indicate that absorption varied from 1 to 8 DAT but was similar across all species. ACPC absorption was greatest at 8 DAT and did not exceed 68% in cogongrass, the most sensitive species. Translocation did not vary significantly from 1 to 8 DAT indicating that translocation was complete by 1 DAT. However, translocation did vary by species. Translocation moving out of the treated area ranged from 59% of applied ACPC in bermudagrass to 71% in cogongrass at 8 DAT. Translocation data indicates that ACPC moves within treated plants when applied to the foliage in a manner consistent with other synthetic auxin herbicides in evaluated species. Metabolism studies indicate that no metabolites exist at 7 DAT, which is consistent with previous research. Metabolism studies were also carried out to 14 DAT. These studies indicate two possible metabolites of ACPC with retardation factor (RF) values less than those of the parent compound. Neither the absorption and translocation nor the metabolism studies offer a definitive conclusion to the differing response of evaluated graminaceous species to ACPC application.