A method and apparatus for disinfesting plant material in a chamber comprising a)a pesticide supply (2) for supplying a vaporising or aerosolised pesticide suchas ethyl formate, b) a mixing device (3) for receiving and mixing the pesticide vapouror aerosol with a volume of diluent gas, and producing a first pesticide mixture,and c) a transfer system (4, 5) for introducing the first pesticide mixture intothe chamber to form a second pesticide mixture. The chamber can be a greenhouse, siloor even a bag or box containing plant material.
