Thunder is a pre emergence, selective, systemic herbicide containing the active ingredient, Butachlor 50% EC. Thunder belongs to the Chloroacetamid chemical family and its mode of action is through inhibition of cell division. Thunder is used to control germinating annual weeds, especially grasses. The primary mechanism of action is through interference with nucleic acid and protein synthesis. Thunder is absorbed primarily through germinating shoots and secondarily by roots. Translocated throughout the plant, with higher concentration in the vegetative parts than the reproductive parts.