A heat gun for treating a surface to destroy weeds and unwanted vegetation uses a lightweight jet engine to generate a hot blast of combustion exhaust, with an optional injector in an engine jacket arranged over the jet engine admixing water with the hot exhaust. The combustion exhaust is discharged through an exhaust nozzle and directed by a shield downwardly into contact with the surface to be treated. The engine is controlled electronically and advanced on a lightweight frame, which may be fitted with a ballast weight and spacer wheels, or be mounted on an advancing arrangement. The jet engine is powered by liquid fuel supplied from a tank. Intake air is cleaned and sound-damped in a filter unit. Combustion takes place at a high pressure and the exhaust discharged hot in a high velocity exhaust stream which instantaneously destroys weeds and unwanted vegetation in the soil contacted therewith.
