Abstract: A vacuum shut off valve mechanism for a soil fumigant applicator includes a pneumatic cylinder that is operably connected to respective fumigant dispensing tubes and shanks of the applicator through a flow divider. A pair of switch operated valves respectively control the flow of fumigant to the flow divider and operation of the pneumatic cylinder. In a first switch state a first valve is opened to deliver fumigant to the flow divider and a second valve operates the pneumatic cylinder to pressurize the flow divider and allow delivery of the fumigant to the dispensing shanks. In a second state, the first valve is closed and the second valve operates the pneumatic cylinder to draw a vacuum, which restricts dripping and leaking of residual fumigant from the tubes and dispensing shanks.