Abstract: The spray marking assembly is mounted on an agricultural or horticultural spraying or spreading implement to show visually, the area traversed so that the overlap or skip may be avoided. Usually, a pump sprays a dye from a tank through hoses to the extremity of the spray boom. This often causes poor markings due to scatter and loss as the pump has to move the fluid through the relatively long lines when demanded and the fluid and/or pressure tends to leak from the lines when not marking. The present device uses a motor and pump which run all the time when in use thus maintaining a constant pressure of fluid in the lines. A solenoid valve is situated at the extremity of the lines adjacent the discharge nozzle so that as soon as the valve is opened, the fluid under pressure is available at the nozzle.