Abstract: In a wheel-mounted sprayer for depositing liquid agricultural chemicals from storage tanks through feeder conduits and multiple spaced-apart spray heads or nozzles onto the ground, a liquid flow detector flow system includes a primary feeder tube forming a part of each feeder conduit, a secondary feeder tube having a larger diameter than the primary feeder tube and being open to the primary feeder tube and to the upper end of a spray nozzle, the feeder conduit being formed into an upwardly extending loop with the primary feeder tube being connected to the secondary feed toward the top of the loop. A pair of adjacent flow detector electrodes extend through an upper portion of the secondary feeder tube near the top of the loop on the downward flow side, and electrical means detects the presence or absence of electron flow between each pair of electrodes.