A method of treating a plant growth medium comprising applying a glyphosate pesticide to the plant growth medium. The treatment may prevent, inhibit, reduce and/or treat clubroot disease, caused by infection with Plasmodiophora brassicae, in one or more plants grown in the plant growth medium. Further provided is use of a glyphosate pesticide to treat a plant growth medium in order to prevent or treat clubroot disease in one or more plants grown in the plant growth medium. Additionally provided is a glyphosate pesticide for use to treat a plant growth medium in order to prevent or treat clubroot disease in one or more plants grown in the plant growth medium. Also provided is a method of treating a piece of agricultural equipment with a glyphosate pesticide.
