Publication Date


Advisor(s) - Committee Chair

Will Normand, James Worthington, Ray Johnson

Degree Program

Department of Agriculture

Degree Type

Master of Science


The lack of effective broadleaf weed control represents one of the major factors having detrimental effects on growth and yield of soybeans. Broadleaf weeds are a serious threat to soybean growers in the southeastern United States. A broad range of herbicides is being used in an effort to control broadleaf weeds in soybeans, and research is still being conducted to find new herbicides that can best work for this purpose. This study involved the use of one these herbicides. It was fomesafen, 5-[2-chloro-4-trifluromethyl) phenoxy]-N-(methyl-sulfonyl)-2-nitrobenzamide, which controls a broad spectrum of broadleaf weeds in soybeans.

The experiment was conducted in the summers of 1987 and 1988. Broadleaf weed control treatments with fomesafen at rates at 0.07, 0.14, 0.28, and 0.35 kg ai/ha in single early postemergence and late postemergence applications were evaluated using the herbicide with a nonionic surfactant at 0.25% and 0.50% of the solution. All treatments were compared with a check which did not receive herbicide application. Among the most common broadleaf weeds found in the area under study during the summer of 1987 were morningglories (Ipomoea spp), redroot pigweed (Amaranthus retroflexus L.), jimsonweed (Datura stramonium L.), common lambsquarters (Chenopodium album L.), carpetweed (Moliugo verticillata L.), and prickly sida (Sida spinose L.), For the summer of 1988 the most prevalent broadleaf weeds were morningglories, horsenettle (Solanum carolinense L.), horseweed [Conyza canadensis (L.), Cronq.], and prickly sida.

The results of the experiment showed no significant differences between early postemergence and late postemergence treatments. There were no significant differences in broadleaf weed control in treatments which received 0.14, 0.28 and 0.35 kg ai/ha of fomesafen for either 1987 or 1988. Poor broadleaf weed control resulted with the application of fomesafen at its lowest rate (0.07 kg ai/ha). No significant differences were found in broadleaf weed control between concentration of 0.25% and 0.50% of the nonionic surfactant added to fomesafen.

Statistically significant yield variation did occur among treatments in 1987. No significant differences in yields were found between any of the herbicide treatments in 1988. Soybean yields were significantly higher in 1988 than in 1987.


Agricultural Science | Agriculture | Agronomy and Crop Sciences | Botany | Plant Sciences | Weed Science