Detroit’s 50 forestry workers have found a new enemy. This time around, a union isn’t mad about technology, innovation, or immigrants.

No, Detroit’s AFSCME Local 542 is ticked off at — tada — VOLUNTEERS.

It seems Detroit was awarded a $200,000 grant to plant trees to replace bunches of them that were killed off by bugs. Grant money would pay for volunteers to be trained to plant the trees.

Not a chance, says the union, which is thwarting signing of the contract.

What will the city council do?