The annual National Fieldays at Mystery Creek, near Hamilton has been postponed due to the coronavirus outbreak.
Fieldays is the largest agribusiness event in the Southern Hemisphere, attracting around 130,000 people over four days each June.
However in a statement, organisers said it would not go ahead as planned.
"Following the recent announcement from the Prime Minister, the New Zealand National Fieldays Society Inc. has regretfully postponed the Fieldays event scheduled for 10-13 June 2020," it said.
"We are currently working through the specifics of what this entails, and will look to continually update stakeholders.
"We thank you for your understanding and patience while we navigate this complicated situation."
In a message to exhibitors, CEO Peter Nation said it was an unprecedented environment.
"We request the time between now and 31 March to present our loyal and longstanding exhibitors and stakeholders with potential options for preserving this event, which we acknowledge is of global significance and has contributed over $18.5B to the economy across the past 51 years of the event," said Nation.
"We thank you for your continued support and consideration."
The postponement follows the cancellation of the Central Districts Field Days which were scheduled to start on Thursday in Fielding.
The AgriFood week event in Manawatu has also been postponed.