u/Healthy-Dog-7986

I tried my hand at activating our sprinkler system this morning. When I turn on the main water supply to the system, it just shoots out of the pipe circled in the picture.

Am I doing something wrong, or is the solution just putting an end cap on this open pipe?

We used a sprinkler service to open and close the system for the last few years; not sure why this pipe would be left open if it causes issues