Chemistry:Benzadox
Benzadox is an amide herbicide, first discovered in 1966 to control kochia on sugarbeet crops.[1] Commercial benzadox products are often sold as benzadox-ammonium, benzadox's ammonium salt.[2] See that page for its chemical properties. Benzadox is not known to be in current use,[3] and most research about it seems to be from the 1960s and 1970s.
Benzadox appears to work by inhibiting photosynthesis, with strong inhibition of alanine aminotransferase and aspartate aminotransferase.[4]
Kochia control
Kochia was the hardest weed to control in sugarbeet around Colorado, Nebraska, Montana and Wyoming. It can emerge at any time while growing sugar beet, and grows 6 inches to 6 feet high. Benzadox came as a breakthrough since it could be applied to weeds post-emergently and selectively on sugarbeet. Selectivity on sugarbeet had been difficult, as kochia belongs to the same chenopodiaceae family.[1]
Applied to sugar-plots in 1967 and 1968, benzadox improved yields from 740, and 2250 lbs/ac. in an unweeded control, to 960 and 3640 lb/ac with 1 lb/ac. of benzadox, up to 4860 and 7920 lb/ac. with 4 lb/ac. of benzadox. No benzadox treated plot had as high a yield as the hand-weeded plot, at 7020 and 8990 lb/ac., due to some weeds persisting and benzadox's crop injury at higher rates to the sugarbeet. The sugar content as a percentage was notably higher in the plots which were hand-weeded or treated with 2 lb/ac. or more of benzadox, because of the reduced competition from weeds.[1]
Rain shortly after herbicide application reduced the effectiveness to virtually nothing, though rain 8 hours after application had relatively little effect. Higher temperature, 70°F compared to 55°F, increased crop injury a lot, though weed control was unaffected.[1]
Commercialisation
It has been manufactured by Murphy Chemical Co and DowElanco.[3]
"Topcide" was a brand name of Gulf Oil Corporation, Agricultural Chemicals Division, with 22.5% benzadox-ammonium by weight, or 2 pounds per US gallon, recommending 1 gallon per acre to be sprayed, (2 lbs per acre active ingredient, or 2.24 kg/Ha) from a tractor sprayer. The 1970 version of the label says control is reduced if the temperature is below 55°F (13°C) or if it rains within 8 hours of spraying. Weeds turn brown within 2 to 5 days, and temporary yellowing or stunning of beets might occur. The mixture was not to be mixed with other herbicides.[5]
References
- ↑ 1.0 1.1 1.2 1.3 Weatherspoon, D. M.; Schweizer, E. E. (1970). "Control of Kochia in Sugarbeets with Benzadox". Weed Science 18 (1): 183–185. ISSN 0043-1745. https://www.jstor.org/stable/4041436. Retrieved 8 February 2026.
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedbcpc - ↑ 3.0 3.1 Cite error: Invalid
<ref>tag; no text was provided for refs nameddatabase - ↑ Nakamoto, Hitoshi; Ku, Maurice S. B.; Edwards, Gerald E. (1982). "Inhibition of C4 photosynthesis by (benzamidooxy)acetic acid". Photosynthesis Research 3 (4): 293–305. doi:10.1007/BF00034110.
- ↑ "Gulf Topcide Post-Emergence Herbicide". Gulf Oil Corporation. 8 January 1970. https://www3.epa.gov/pesticides/chem_search/ppls/004090-00129-19700108.pdf.
External links
- Benzadox in the Pesticide Properties DataBase (PPDB)
- Benzadox-ammonium in the Pesticide Properties DataBase (PPDB)
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