Claimed is a herbicidal composition comprising mesotrione (trade names Callisto(RTM) and Tenacity(RTM), IUPAC 2-(4-mesyl-2-nitrobenzoyl)cyclohexane-1,3-dione) and a base where, preferably, the mesotrione is present in an amount of from 1-80 wt.% or, more preferably, 1-60 wt.%. When diluted 100-fold with water the pH of the resulting solution may be, preferably, greater than 7 and, most preferably, from 8 to 10. Preferably, the cation of the base is either sodium, potassium, lithium or ammonium and the cation may be carbonate, phosphate, oxide, hydroxide, acetate or silicate. Preferably, the base is one of sodium carbonate, sodium phosphate, potassium carbonate and potassium phosphate; most preferably, the base is sodium carbonate. It is preferable that the base is present in the composition from 0.01 to 15 wt.% or, more ideally, 0.5 to 10 wt.%. The composition may be formed as either water-dispersible granules or a wettable powder. The composition may further comprise a wetting agent, dispersing agent, antifo
