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United States Department of Agriculture

Agricultural Research Service

Title: Uptake, Translocation, and Metabolism of Sulfentrazone and Sulfentrazone Plus Clomazone in Flue-Cured Tobacco Transplants

Authors
item Fisher, L - NORTH CAROLINA STATE UNIV
item Burke, I - NORTH CAROLINA STATE UNIV
item Price, Andrew
item Smith, W - NORTH CAROLINA STATE UNIV
item Wilcut, J - NORTH CAROLINA STATE UNIV

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2006
Publication Date: October 1, 2006
Citation: Fisher, L.R., Burke, I.C., Price, A.J., Smith, W.D., Wilcut, J.W. 2006. Uptake, translocation, and metabolism of sulfentrazone and sulfentrazone plus clomazone in flue-cured tobacco transplants. Weed Technology. 20:898-902.

Interpretive Summary: Tobacco farmers have traditionally used many options for weed management including; crop rotations, cultivation, hand weeding, and herbicides. Currently, only six herbicides are registered for use in tobacco production in North Carolina. The most widely used herbicides include clomazone, pendimethalin, and sulfentrazone. Occasional early season stunting from sulfentrazone has been observed A mixture of sulfentrazone and clomazone is very common in tobacco because of broad spectrum weed control. Additionally, field and greenhouse research has shown reduced injury from a mixture of sulfentrazone plus clomazone compared to sulfentrazone alone. An understanding of the physiological basis for tolerance of tobacco to sulfentrazone, and evaluation of the potential basis of safening of sulfentrazone from clomazone would assist in the development of recommendations for the use of sulfentrazone to minimize the risk for injury in tobacco transplants. 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 percent 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. Sulfentrazone was also readily metabolized by tobacco transplants and differences were observed between sulfentrazone alone and the mixture with clomazone. After 3 h, 66 versus 91% of the 14C recovered in the leaves was metabolized when sulfentrazone was used alone compared to the mixture, respectively. This difference may indicate that metabolism of sulfentrazone by tobacco transplants was enhanced by the presence of clomazone. Over the next 6 h, percentage of sulfentrazone metabolized did not change with either sulfentrazone alone or the mixture of sulfentrazone and clomazone. Data suggest that tolerance of tobacco to sulfentrazone is a result of metabolism. The observed reduction in injury to tobacco transplants from the mixture of sulfentrazone plus clomazone compared to sulfentrazone alone may be the result of the enhanced metabolism of sulfentrazone observed in this study. However, “safening” of sulfentrazone by clomazone and tolerance of tobacco under field conditions has been inconsistent.

Technical Abstract: 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 percent 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. Sulfentrazone was also readily metabolized by tobacco transplants and differences were observed between sulfentrazone alone and the mixture with clomazone. After 3 h, 66 versus 91% of the 14C recovered in the leaves was metabolized when sulfentrazone was used alone compared to the mixture, respectively. This difference may indicate that metabolism of sulfentrazone by tobacco transplants was enhanced by the presence of clomazone. Over the next 6 h, percentage of sulfentrazone metabolized did not change with either sulfentrazone alone or the mixture of sulfentrazone and clomazone.

Last Modified: 4/23/2014
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