We farm around 6,000 acres and we do not have hunting privileges on most of it, Some of it we do , but it is in the lease agreement. The landowner might have given someone permission to hunt there and put up a treestand, check and see , he might be renting it to a legit hunter, just because you farm it the owner is still the owner, We have 54 landlords and many different agreements. If the landowner doesn't know anything about it, I would knock it down and destroy it, saying nothing about it to anyone other than the landlord...