An apparatus, useful for agricultural applications, comprises: a) a portable frame; b) a water reservoir mounted on the frame which defines an upstream end of a fluid passageway carried by the frame; c) a first chamber disposed along the fluid passageway downstream of the reservoir which includes a heater operable to convert water flowed from the reservoir and through the chamber into steam; d) a second chamber disposed along the fluid passageway which is constructed to be sufficient to receive steam at a first temperature range downstream of the first chamber and to heat the received steam to a second temperature range, wherein the steam at the second temperature range is superheated ; e) a steam separator disposed along the fluid pathway and being between the first and second chambers which is able of separating liquid from the steam flowing in the passageway and f) an outlet adapted to deliver a flow of superheated steam from the second chamber. Methods for treating plants and fields in agricultural applic
