Abstract: The invention provides a method of cleaning greenhouse roofs mechanically to remove the accumulation of dust and grit. The method comprises at least one dust cleaning device moving over a soft roof The cleaning device is controlled to follow the irregular surface of the soft roof with limited pressure to avoid damage. The invention also provides a dust-cleaning system to remove dust and grit from the soft roof.

Abstract: Equipment for spraying plants and trees with a plant treating liquid injected into turbulent pulsating air streams, including at least one oblong air outlet structure for issuing turbulent pulsating air streams in diverging directions. The air outlet structure has an oblong air inlet opening for receiving pressurized air and includes a plurality of longitudinally arranged air outlets extending outwardly from the air inlet opening. The air outlets each have a respective axis whose angle of inclination differs with respect to an angle of inclination of an adjacent air outlet. At least one spray nozzle is arranged to inject a plant treating liquid into the turbulent pulsating air streams issued from the air outlet structure.