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Title: Persistence of triclopyr in Alaska subarctic environments

Author
item Seefeldt, Steven
item BARNES, DAVID - UNIVERSITY OF ALASKA
item Ranft, Richard
item RHODES, WILLIAM - UNIVERSITY OF ALASKA
item SCHNABEL, WILLIAM - UNIVERSITY OF ALASKA

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2008
Publication Date: 2/8/2009
Citation: Seefeldt, S.S., Barnes, D.L., Ranft, R., Rhodes, W.J., Schnabel, W.E. 2009. Persistence of triclopyr in Alaska subarctic environments [abstract]. Weed Science Society of America Meeting Abstracts. Paper no. 517.

Interpretive Summary:

Technical Abstract: Field dissipation and vertical mobility of the butoxyethyl ester of triclopyr was assessed in two distinct geographic locations within the state of Alaska. Interior sites near Delta Junction included vegetated plots within highway rights-of-way (ROW) and Conservation Reserve Program (CRP) fields and a coastal site within ROW near Valdez. Triclopyr was broadcast applied at 2.2 kg ai/ha with 0.25% v/v non-ionic surfactant (talloil) on the ROW, whereas a dose-response study was used on CRP fields with 2.2, 1.1, 0.6 and 0.3 kg ai/ha. Soil samples were collected at 0-5, 10-18 (in the ROW), 15-30 (in the CRP), and 30-38 cm depths before, immediately following application and periodically over the course of a year. Environmental conditions were monitored and soil properties were measured. Soil samples were extracted with diethyl ether and esterified with boron trifluoride to enable analysis via gas chromatograph mass spectrometer. Triclopyr residues persisted at the 0-5 cm depth for at least 300 days following application at all sites. Transient increases in concentration at the 0-5 cm depth were observed, presumably resulting from residue wash-off associated with precipitation events or, in the spring, possible deposition from treated vegetation on the ground surface. Vertical mobility of triclopyr was limited, indicated by a large proportion of non-detects and relatively low concentrations recorded at the 10-18 cm and 30-38 cm depths. Increased amounts of vegetation at the Valdez location resulted in reduced amounts of triclopyr in the soil. Degradation rates at both sites were equivalent during the growing season. If triclopyr were to reach ground or surface waters through transport from the target area, concentrations should remain well below toxic levels with respect to aquatic and terrestrial organisms.