Does the shrink effect caused by the Wand of Wonder last the full minute?


One player in my campaign just used the Wand of Wonder and got the effect:

66-69 — You shrink yourself as if you had cast enlarge/reduce on yourself.

Enlarge/reduce has a duration of:

Concentration, up to 1 minute

Does the effect last the full minute, or can you end the effect early?

We ruled that it’s the full minute because the wand is the one that cast the effect so it’s “concentrating”. Is this correct?