Abstract: A control valve for automatically controlling fluid fertilizer is introduced in a fluid fertilizer application system of the type comprising: a fertilizer supply; an implement having fertilizer application elements; means for moving said application elements between a lowered, application position and a raised, transport position; and conduit means for delivering fertilizer from the fertilizer supply to the application elements. The control valve is interposed in the conduit means between the fertilizer supply and the application elements and has a control lever terminating in a saddle adapted to receive a projection. A collapsible and extendable valve actuator means, which is responsive to the means for moving the application elements between raised and lowered positions and which has thereon a projection adapted to engage the valve control lever, controls the valve such that it is closed when the application elements are raised and open when the application elements are lowered.