A car was damaged when the boom of an irrigation unit being towed by a tractor hit it in Earnscleugh Rd, Central Otago on July 19.
Police are asking for help to locate the tractor driver.
Senior Constable Michael Colligan said it was possible the driver might not have realised the crash significantly damaged the car.
The blue Ford tractor had been towing an irrigation unit when the pin came out and the boom unit began swinging from side to side.
The boom hit a car parked on the side of the road and the owner reported the damage when he discovered it.
A member of the public saw the incident, and stopped to help the tractor driver and help him secure the pin.
Anyone who knows who the driver might be, or the driver himself, should contact police on (03) 440-2500.