A herbicidal composition comprises microcapsules, the microcapsules having a capsule wall of a porous condensate polymer, wherein the microcapsules contain clomazone and a solvent comprises rosin and/or a rosin derivative. In one embodiment the microcapsules are in an aqueous suspension. Also claimed is a method of preparing a herbicidal composition, the method comprises the steps of: providing a water immiscible phase comprising clomazone, an isocyanate and optionally an acetylene carbamide derivative (ACD) cross-linker, dissolved in a rosin solvent system comprising rosin and/or a rosin derivative； providing an aqueous phase comprising one or more surfactants； combining the water immiscible phase and the aqueous phase to form a dispersion of the two phases； thereby forming microcapsules of polyurea containing droplets of the water immiscible phase； and curing the microcapsules.
