An apparatus suitable for controlling unwanted vegetation which apparatus comprises a reservoir (2), release means (6) connected to the reservoir (2), and a nozzle (10) for applying a stream of foam including steam, connected to the reservoir (2) through the release means (6). A liquid is heated in the reservoir (2) to an elevated pressure, the liquid comprising water and a surfactant, i.e. a foaming agent, and forms a foam when discharged through the nozzle (10). The foam contains steam, and is effective at killing the foliage.
