A liquid spraying system for spraying agricultural chemicals comprising: a liquid spray section having at least one liquid spray nozzle; a liquid controller for controlling the flow of liquid from a liquid supply of an agricultural chemical to said spray section for discharge from said at least one spray nozzle; said liquid controller including a liquid control valve having a valve body (50, 51) with a liquid supply port, a liquid outlet port, and a liquid flow back port; a first liquid supply line for directing liquid from said liquid supply to said liquid supply port; a second liquid supply line for directing liquid from said liquid supply port to said spray section; a flow back line coupled to said flow back port for directing liquid in said second liquid supply line away from said spray section upon termination of the supply of liquid to said spray section; said control valve having a valve stem characterized by; said control valve being operable for moving said valve stem between a first position that opens said liquid supply port for enabling the direction of liquid from said first liquid supply line through said liquid supply port and liquid outlet port to said second liquid supply line and liquid spray section for discharge from said at least one spray nozzle while blocking flow of liquid through said flow back port to said flow back line, a second position that blocks the supply of liquid from first liquid supply line through said liquid supply port to said liquid outlet port and second liquid supply line while continuing to block the flow of liquid through said flow back port to said flow back line; and to a third position wherein during movement to said third position said valve stem continues to block the flow of liquid from said first liquid supply line through said liquid supply port and liquid outlet port while opening said flow back port for allowing remaining liquid in said second liquid supply line to flow back through said flow back port and flow back line such that the flow of liquid from said second liquid supply line to said liquid flow back line is only possible when said liquid supply port is closed. a liquid spray section having at least one liquid spray nozzle; a liquid controller for controlling the flow of liquid from a liquid supply of an agricultural chemical to said spray section for discharge from said at least one spray nozzle; said liquid controller including a liquid control valve having a valve body (50, 51) with a liquid supply port, a liquid outlet port, and a liquid flow back port; a first liquid supply line for directing liquid from said liquid supply to said liquid supply port; a second liquid supply line for directing liquid from said liquid supply port to said spray section; a flow back line coupled to said flow back port for directing liquid in said second liquid supply line away from said spray section upon termination of the supply of liquid to said spray section; said control valve having a valve stem characterized by; said control valve being operable for moving said valve stem between a first position that opens said liquid supply port for enabling the direction of liquid from said first liquid supply line through said liquid supply port and liquid outlet port to said second liquid supply line and liquid spray section for discharge from said at least one spray nozzle while blocking flow of liquid through said flow back port to said flow back line, a second position that blocks the supply of liquid from first liquid supply line through said liquid supply port to said liquid outlet port and second liquid supply line while continuing to block the flow of liquid through said flow back port to said flow back line; and to a third position wherein during movement to said third position said valve stem continues to block the flow of liquid from said first liquid supply line through said liquid supply port and liquid outlet port while opening said flow back port for allowing remaining liquid in said second liquid supply line to flow back through said flow back port and flow back line such that the flow of liquid from said second liquid supply line to said liquid flow back line is only possible when said liquid supply port is closed.