Mesotrione is an organic compound that is used as a selective herbicide, especially in maize and corn. It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) and is sold under brand names including Callisto and Tenacity. It was first marketed by Syngenta in 2001. The discovery of the triketone class of herbicides started with the observation in 1977 of weed control near a bottlebrush tree, Callistemon citrinus. Chemists at the Stauffer Chemical Company identified the compound responsible as leptospermone, a known natural product which had not previously been reported as having biological activity. Extensive work on analogues led to the discovery and development of mesotrione.

The triketone herbicides were found to be effective on a wide range of commercially-important weed species and to have both pre- and post-emergence activity. Mesotrione possesses a broad spectrum of activity on commercially important broadleaf weeds including Abutilon theophrasti, Amaranthus powellii, Amaranthus retroflexus, Chenopodium album, Datura stramonium, Digitaria sanguinalis, Lamium purpureum, Polygonum persicaria, Rumex crispus, Senecio vulgaris, Solanum nigrum, Stellaria media and Xanthium strumarium. In addition, its properties mean that it can be applied to soil so emerging weeds take it up and are controlled. Alternatively, spraying after weeds are already present in the crop will also lead to control. It is started to be seen to be used in a home situation with lawns.

Mesotrione is very toxic to aquatic life with long lasting effects.

Formal Chemical Name (IUPAC)
2-(4-mesyl-2-nitrobenzoyl)cyclohexane-1,3-dione

References

https://en.wikipedia.org/wiki/Mesotrione