Field and Laboratory Dissipation of the Herbicide Fomesafen in the Southern Atlantic Coastal Plain (USA).
To control weeds with evolved resistance to glyphosate, Southeastern (USA) cotton farmers have increased fomesafen (5-(2-chloro-α,α,α-trifluoro-p-tolyloxy)-N-mesyl-2-nitrobenzamide) use. To refine fomesafen risk assessments, data are needed that describe its dissipation following application to farm fields. In our study, relatively low runoff rates and transport by lateral subsurface flow, <1.0 and 0.15% of applied respectively, were observed. The low runoff rate was linked to postapplication irrigation incorporation and implementation of a common conservation tillage practice. Moderate soil persistence (t1/2 = 100 days) was indicated in laboratory incubations with surface soil, however, analysis of soil cores from treated plots showed that ≈3% of fomesafen applied persisted in subsoil >3 years after application. Findings suggest low potential for fomesafen movement from treated fields, however, the fate of fomesafen that accumulated in subsoil and the identity of degradates are uncertain. Soil and water samples were screened for degradates, but, none were detected.
Southeast Watershed Research Laboratory, USDA-ARS , P.O. Box 748, Tifton, Georgia 31793, United States.
Thomas L
TL
Potter
Southeast Watershed Research Laboratory, USDA-ARS , P.O. Box 748, Tifton, Georgia 31793, United States.
David D
DD
Bosch
Southeast Watershed Research Laboratory, USDA-ARS , P.O. Box 748, Tifton, Georgia 31793, United States.
Timothy C
TC
Strickland
D000383:Agriculture; D001549:Benzamides / Q000737:chemistry*; D004784:Environmental Monitoring; D006540:Herbicides / Q000737:chemistry*; D007700:Kinetics; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D014481:United States; D014874:Water Pollutants, Chemical / Q000737:chemistry
D001549:Benzamides; D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C088563:fomesafen
conservation tillage; conventional tillage; leaching; metabolites; pesticide transport; strip tillage