Tribenuron in the form of tribenuron-methyl is a sulfonylurea herbicide. Its

mode of action In pharmacology and biochemistry, mode of action (MoA) describes a functional or anatomical change, resulting from the exposure of a living organism to a substance. In comparison, a mechanism of action (MOA) describes such changes at the molecul ...

is the inhibition of

acetolactate synthase The acetolactate synthase (ALS) enzyme (also known as acetohydroxy acid or acetohydroxyacid synthase, abbr. AHAS) is a protein found in plants and micro-organisms. ALS catalyzes the first step in the synthesis of the branched-chain amino acids ...

, group 2 of the Herbicide Resistance Action Committee's classification scheme.

Chemistry

In the 1970s, chemists at

DuPont Dupont, DuPont, Du Pont, duPont, or du Pont may refer to: People * Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...

worked extensively on sulfonylurea herbicides, following the invention of this class of herbicides by George Levitt which had led to the commercialisation of chlorsulfuron. Tribenuron (the

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

) and its methyl

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

were first disclosed in general terms in one of Levitt's patents and subsequently the ester was subject to further patenting and selected for development under the code name DPX L5300. In the final step of its synthesis, 2-methoxycarbonylbenzenesulfonyl isocyanate was condensed with 2-methylamino-4-methoxy-6-methyl-1,3,5-triazine to form the

sulfonylurea Sulfonylureas or sulphonylureas are a class of organic compounds used in medicine and agriculture. The functional group consists of a sulfonyl group (-S(=O)2) with its sulphur atom bonded to a nitrogen atom of a ureylene group (N,N-dehydrourea ...

product. : Tribenuron synthesis

Mode of action

Tribenuron is an

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

that acts as an acetolactate synthase inhibitor. For the purposes of herbicide resistance management, the Herbicide Resistance Action Committee has placed it in group 2 (legacy HRAC Group B).

Applications

Tribenuron has a broad spectrum of activity on commercially important broadleaf weeds and grasses but at the recommended use rate it is safe to important crops such as wheat. When introduced by DuPont, its recommended application rate was . The estimated use in US agriculture is mapped by the US Geological Service and shows that from 1992 to 2018, up to were applied each year. The compound is used mainly in wheat but also in pasture.

Physicochemistry

In a clay-water suspension, tribenuron has increased

sorption Sorption is a physical and chemical process by which one substance becomes attached to another. Specific cases of sorption are treated in the following articles: ; Absorption: "the incorporation of a substance in one state into another of a d ...

with decreasing pH and even more so with

suspended load The suspended load of a flow of fluid, such as a river, is the portion of its sediment uplifted by the fluid's flow in the process of sediment transportation. It is kept suspended by the fluid's turbulence. The suspended load generally consists ...

. p.248.

Resistant crops

A tribenuron-resistance transformation has been achieved in

watermelon The watermelon (''Citrullus lanatus'') is a species of flowering plant in the family Cucurbitaceae, that has a large, edible fruit. It is a Glossary of botanical terms#scandent, scrambling and trailing vine-like plant, and is plant breeding ...

and validated by survival of the ''als'' mutants but not the controls, under tribenuron treatment. Two

oilseed Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of edible plants. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed ...

type

sunflower The common sunflower (''Helianthus annuus'') is a species of large annual forb of the daisy family Asteraceae. The common sunflower is harvested for its edible oily seeds, which are often eaten as a snack food. They are also used in the pr ...

cultivars have been produced by

USDA The United States Department of Agriculture (USDA) is an United States federal executive departments, executive department of the Federal government of the United States, United States federal government that aims to meet the needs of commerc ...

- ARS by conventional breeding.

Chemistry

Mode of action

Applications

Physicochemistry

Resistant crops

References

Further reading