Research was conducted to evaluate root uptake, translocation, and metabolism of ¹⁴C-sulfentrazone alone or in a mixture with clomazone in solution in flue-cured tobacco transplants. Uptake and translocation of sulfentrazone was rapid and was not affected by the addition of clomazone. Fifty-nine and 65% of the ¹⁴C absorbed by the plant was translocated to the leaves within 24 h with sulfentrazone alone and in the clomazone plus sulfentrazone mixture, respectively. Differences in plant metabolism were observed between sulfentrazone alone and sulfentrazone plus clomazone. After 3 h, 66% of the ¹⁴C recovered from the leaves was metabolized when sulfentrazone was applied alone, compared to 91% when sulfentrazone was applied with clomazone. The difference could indicate that metabolism of sulfentrazone by tobacco transplants was enhanced by the presence of clomazone.

Nomenclature: Clomazone, sulfentrazone, flue-cured tobacco, Nicotiana tabacum L. ‘NC 71’.

Additional index words: Enhanced metabolism, safening, tolerance.

Abbreviations: HAT, hours after treatment; LSS, liquid scintillation spectrometry; PPI, preplant incorporated treatment; PRE-T, pre-emergence soil surface treatment.