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United States Department of Agriculture

Agricultural Research Service

Title: Kenaf (Hibiscus Cannabinus L.) Herbicide Uptake and Weed Competition

Author
item Webber, Charles

Submitted to: Kenaf Association International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 15, 1997
Publication Date: N/A

Interpretive Summary: Kenaf is grown for a variety of uses including: oil absorbents, potting soil amendment, drilling mud component, animal bedding, livestock feed, and speciality paper. Although there is now a great deal of information concerning effective herbicides for kenaf production, no kenaf herbicide research has investigated the presence of herbicide residues in kenaf plant tmaterial. If kenaf plant material has the potential of entering the human food system through livestock feed or animal bedding, it's important to determine if herbicides are present in kenaf plant material. The objectives of this research were to determine if herbicide residues were present in kenaf plant material, determine the effect of two herbicides, trifluralin and pendimethalin, on kenaf yield parameters and determine the effect of weed competition on kenaf yields. In 1993 and 1994 research was conducted at Lane, Oklahoma using trifluralin and pendimethalin applied as preeemergence herbicides at three rates (0.5, 1.0 and 2.0 lb/a). No visua crop injury or herbicide residues were detected for trifluralin or pendimethalin at any of the application rates or harvest dates, 75 and 150 days after planting, for either year. The tested herbicides did not reduce plant populations or stalk yields. Weed competition reduced stalk yields and stalk percentages across years for the 75 days after planting. Trifluralin and pendimethalin are promising herbicides for use in kenaf production. Expanding the registration label to include these herbicides for use in kenaf production for livestock feed would be beneficial in establishing kenaf as a commercial crop.

Technical Abstract: Herbicides are now used in the commercial production of kenaf (Hibiscus cannabinus L.). Kenaf is grown for a variety of uses including: oil absorbents, potting soil amendment, drilling mud component, animal bedding, livestock feed, and speciality paper. If kenaf plant material has the potential of entering the human food system, it is important to determine if herbicides are present in kenaf plant material. Although there is a growing knowledge base concerning the effectiveness of both preemergence and postemergence herbicides for kenaf production, there is no research concerning the presence of herbicide residues within kenaf plant material. The objectives of this research were to determine if herbicide residues were present in kenaf plant material, determine the effect of two herbicides on kenaf yield parameters and determine the effect of weed competition on kenaf yields. A two-year field study was conducted at Lane, ,Oklahoma on a fine sandy loam. Trifluralin and pendimethalin were applied as preemergence herbicides at three rates (0.56, 1.12 and 2.24 kg ai/ha). The experiments also included a weed-free and a weedy-check treatment. Kenaf cultivar 'Tainung #2' was planted during May of 1993 and 1994. Data and plant samples were collected at two harvest dates, 75 and 150 days after planting. There were no visual phytotoxicity symptoms observed for either herbicide. Chemical and data analyses determined that trifluralin and pendimethalin were not present in kenaf at detectable levels for any of the application rates for either harvest date. Weeds in the weedy-check treatment reduced kenaf stalk yields at 75 DAP by an average 1.8 t/ha compared to the weed-free treatment.

Last Modified: 8/27/2014
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