Abstract: An apparatus and a method for combating crops with a heated air flow involve a gas burner unit that is only activated if the pressure, the flow rate or the rotational speed of the ventilator is greater than a determined threshold value; and the gas burner unit is again deactivated if the pressure, the flow rate or the rotational speed of the ventilator is less than the determined threshold value.

Abstract: A device is described for preventing damage to crops by means of heated ambient air, the device comprising gas reservoirs a gas burner, a centrifugal fan and a heating device. The heating device branches off a part of the flow of the heated ambient air to an outlet of the centrifugal fan and allows it to flow to the bottom side of the at least one gas reservoir.

Abstract: A method and apparatus are described for the control of vegetation by means of a heated gas that is generated in a burner and which via an outflow opening of an outlet channel is passed to the vegetation to be controlled. A fan is arranged between the burner and the outlet channel in order for the fan, while in operation, to suck in the heated gas from the burner and discharge it to the outlet channel and thereby exhibiting a flame-retarding action.