Fate of Bromoxynil n-Butyrate and iso-Octanoate Applied as a Mixture to a Wheat Field
1994
Grover, R. | Smith, A. E. | Cessna, A. J.
Dissipation of bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), applied as a 1:1 mixture of the n-butyrate and iso-octanoate esters, in the air, crop, and soil components was measured in a spring wheat (Triticum aestivum L.) field, both during and following its application. Drift losses during spraying were <1% of the amount applied, with no phenol derivative being detected in air samples collected during application. Following application, cumulative vapor loss for the n-butyrate and iso-octanoate esters (phenol equivalent, p.e.) over the 5-d postapplication period were estimated to be 16 and 7%, respectively. Little or no free phenol residues were detected in the air above the treated field. The crop canopy intercepted approximately 20% of the application. Ester deposits on plant surfaces were rapidly dissipated with >75% of the total ester residues on the crop being lost or hydrolyzed 24 h after treatment. There were no detectable residues in the seed or straw at harvest. In the soil, the half-lives of n-butyrate and iso-octanoate were <1 and ∼4 d, respectively. Hydrolysis was, however, more rapid under moist soil conditions, with the n-butyrate being converted more rapidly to phenol than the iso-octanoate. Phenol breakdown was also moisture dependent but much slower, with >95% dissipation occurring only after 8 wk.
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