Abstract: A spray apparatus for the treatment of a harvested crop, the apparatus including a high voltage electrostatic spray head, a sprayhood surrounding the sprayhead and having an aperture opposite the sprayhead and insulating means to suspend the sprayhood with the aperture adjacent a region of a conveying path to establish and maintain the sprayhood covering said region of said conveying path, the sprayhood having on the outside an insulating cover and inside the cover an extensive insulated electrode extending around and above said aperture, the electrode being energizable in operation to a potential similar to that applied to the sprayhead, whereby the support means and electrode together permit the application of an electrostatically charged spray from the sprayhead in a controlled manner throughout said region of the conveying path under the sprayhood to a quantity of crop conveyed past on the conveying path in a regular manner.

Abstract: A spray apparatus for the treatment of a harvested crop, the apparatus including a high voltage electrostatic spray head, a sprayhood surrounding the sprayhead and having an aperture opposite the sprayhead and insulating means to suspend the sprayhood with the aperture adjacent a region of a conveying path to establish and maintain the sprayhood covering said region of said conveying path, the sprayhood having on the outside an insulating cover and inside the cover an extensive insulated electrode extending around and above said aperture, the electrode being energizable in operation to a potential similar to that applied to the sprayhead, whereby the support means and electrode together permit the application of an electrostatically charged spray from the sprayhead in a controlled manner throughout said region of the conveying path under the sprayhood to a quantity of crop conveyed past on the conveying path in a regular manner.

Abstract: An electrostatic crop spraying apparatus is arranged so that spray is ejected from the nozzle directly towards the crop, either vertically downwards or at an angle intermediate between the horizontal and the vertical. With respect to the vertical, the spray liquid is fed to the upper surface of a rotatable disc from which it is centrifugally distributed on to the inner surface of a rotatable hollow cone coaxial with the disc. The truncated apex of the cone is uppermost and the liquid is atomized on ejection from the lower circumferential edge of the cone. Charging of the spray is produced at the surface of the disc or of the cone by means of an electrode which maintains an ionized air path to the surface over a distance of a few mm. The current flow for an electrode potential in the range 15 to 30kV is a few .mu.A. A pump may be used to supply liquid to the nozzle in a pulsed flow.