The paper concerns adaptation of the graphical parallel programming environment PS-GRADE based on advanced global synchronization and control mechanisms to grid-level application control. We propose that program execution control by synchronizers known at the process level is extended and used to coordinate parallel applications executed on grid. We introduce explicit inter-application, or grid-level, synchronizers. The grid-level synchronizers generate application execution control decisions based on predicates computed on global application states. They co-operate with application level synchronizers, which are able to send state reports and receive control signals over Grid communication network. In the proposed solution, the application workflow paradigm has been enriched to enable designing more flexible control between otherwise independent applications. We discuss types of grid applications whose global control can be implemented by the use of synchronizers-based infrastructure. An application example illustrates the proposed control design strategy.