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Picloram Movement in an Appalachian Hardwood Forest Watershed
Author(s) -
Neary D. G.,
Bush P. B.,
Douglass J. E.,
Todd R. L.
Publication year - 1985
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1985.00472425001400040023x
Subject(s) - picloram , environmental science , hexazinone , sowing , understory , hardwood , watershed , agronomy , biology , botany , weed control , canopy , machine learning , computer science
Picloram (4‐amino‐3,5,6‐trichloropicolinic acid) was applied at a rate of 5.0 kg ha −1 acid equivalent to 4 ha of the 28‐ha Watershed 19, Coweeta Hydrologic Laboratory in western North Carolina. The herbicide was broadcast manually as a pellet formulation (10% acid equivalent) in May 1978. The objective was to eliminate a poor‐quality mixed oak overstory and rhododendron ( Rhododendron maximum L.)‐laurel ( Kalmia latifolia L.) understory prior to planting white pine ( Pinus strobus L.). Picloram residues in samples from an Umbric Dystrochrept soil peaked in concentration in the upper 0.07 m at 11.58 mg kg −1 , had a half‐life of about 4 weeks, and declined to near detection limits 28 weeks after application. Soil solution contained the highest picloram levels at 0.6 m (peak of 350 mg m −3 ). Picloram residues were detected in soil solution 1.2 m into the soil, but concentrations were < 25 mg m −3 , and persisted for only 60 weeks. Intensive sampling of two springs detected trace levels for a period of 18 d. Only sporadic, low‐level picloram residues were detected in streamflow from nested 10‐ha and 28‐ha watersheds during a 70‐week period. Use of the herbicide picloram did not affect the quality of streamflow from Watershed 19 for domestic or agricultural purposes.