It is the third quad bike fatality this year, according to the Ministry of Business, Innovation and Employment.
Simple safety messages around the use of quad bikes could "go a long way to preventing these utterly unnecessary deaths", said Chief Coroner Judge Neil MacLean.
Sadly, the number of incidents did not appear to be reducing, he said.
Quad bikes were okay when used for the purpose for which they were designed but when pushed beyond that, or used by children, they became potentially dangerous, he said.
"I suspect that the key message is training and awareness that they're not toys.
"They're not something that kids should be around."
Judge MacLean acknowledged there was much debate around protective measures such as rollbars on bikes.
"Sometimes the very protective device itself can be the cause of injury that might not have otherwise happened."
There were many other near misses, he said.
A push by the ministry was launched last month to reinforce safety messages to reduce quad bike injuries and fatalities.
Typically, five people will die and 850 will be injured each year in accidents involving quad bikes on farms, according to its figures.
As in any workplace, farm owners and managers are required to take practicable steps to control hazards and under-aged riders on their farms.
All manufacturers of quad bikes sold in New Zealand state children younger than 16 may not ride an adult-sized quad bike for this reason.