A police spokeswoman said the incident happened about 1.50pm on a rural property in Earnscleugh Rd.
Police later confirmed the death and said it would be referred to the coroner.
WorkSafe was also notified.
The tractor had rolled while on a driveway next to a building site on a vineyard on Earnscleugh Rd near the intersection with Marshall Rd.
The Otago Daily Times understands the operator of the tractor had been spraying vineyard rows before the incident.
Police, a St John ambulance, and a single Fire and Emergency New Zealand (Fenz) appliance attended.
A Fenz spokesman said the single appliance remained at the scene for more than two hours to deal with the chemical that was on the back of the tractor.