An upstate New York farm owner admitted to criminal child labor violations in the July 2015 death of a 14-year-old worker crushed while using a hydraulic lift to move hay bales.

Luke Park, the owner of the Park Family Farm in Homer, N.Y., pleaded guilty to charges of endangering the welfare of a child, employing a minor in prohibited work, and willfully failing to pay unemployment-fund contributions in his Sept. 20 plea in Cortland County Court. He was charged with...