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Dissipation of Clopyralid and Picloram in Soil and Seep Flow in the Blacklands of Texas
Author(s) -
Bovey R. W.,
Richardson C. W.
Publication year - 1991
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/jeq1991.00472425002000030005x
Subject(s) - clopyralid , picloram , leaching (pedology) , environmental science , surface runoff , soil water , hydrology (agriculture) , chemistry , environmental chemistry , agronomy , soil science , geology , ecology , biology , weed control , geotechnical engineering
The dissipation, leaching and movement of clopyralid (3,6‐dichloro‐2‐pyridinecarboxylic acid) and picloram (4‐amino‐3,5,6‐trichloro‐2‐pyridinecarboxylic acid) were determined in soil and subsurface water after spray application of the herbicides to the surface of an area overlying a shallow perched water table in the Blacklands of Texas. A 1:1 mixture of the monoethanolamine salt of clopyralid and the tri‐isopropanolamine salt of picloram was applied at 0.56 kg a.i./ha each in May 1988 and June 1989 on the same area. Approximately 90 d after treatment, >99% of the clopyralid and >92% of the picloram had dissipated. Most herbicide was detected in the upper 30 cm of soil. No herbicide was detected in subsurface water from the area treated in 1988, but concentrations of <6 mg/m 3 of clopyralid and <5 mg/m 3 of picloram were detected in subsurface water collected 11 and 41 to 48 d after treatment in 1989.