The cull, of around 126,000 in addition to the 26,000 already underway, will take place over one to two years.
Mycoplasma bovis is a bacterium that causes udder infections (mastitis), abortion, pneumonia and arthritis in cattle.
It does not infect humans and presents no food safety risk.
Ashburton farmer Frank Peters said the announcement was gutting and he thought there would be more time allowed for the eradication.
Peters had been placed on depopulation notice by the Ministry for Primary Industries and had already lost 1000 cattle from the cull.
He had 500 cattle and 500 calves left which would likely also be culled.
The cost of losing his herd would be a cost on his family, the amount was unquantifiable.
"The mental state of everyone is on tender hooks. No sleep, you don't sleep and think is this a bad dream? But no you wake up and it is the same thing.
"It is every day we have another thing to deal with."
He bought his father's herd of 80 cattle in 1983 and started his farming life then.
That would be 55 years of breeding history lost.
"It does hurt and you can't replace that," he said.
Agriculture and Biosecurity Minister Damien O'Connor said as a former sharemilker and farmer he could relate to the "terrible situation facing anyone who has to cull their herd".
"It's really tough on the families who are directly in the firing line of this terrible disease. It's up to us to work together and support them."
Federated Farmers president Katie Milne called it an "excruciating experience".
"We're going to wrap around some really good support around our farmers who are going to go through this. This is a tough time, and the pain and anguish they're going to go through is really hideous and we have to support them as neighbours, community members, farmers, friends and so on."
Rural Women New Zealand president Fiona Gower said her organisation was ready to support those affected, especially women and children.
"We are committed to ensuring there are wraparound welfare support for those affected because we understand that without this, high levels of stress in times of any crisis and in the aftermath can lead to a breakdown in our rural social fabric.
"The last thing we need is the bullying of our children, an increase in family violence or even suicide," she said.
DairyNZ said it stood with the Government in support of the decision to try to eradicate the cattle disease.
"We know that moving towards eradication will be a devastating decision for some, and will mean that thousands of animals will have to be culled," said DairyNZ chair Jim van der Poel.
Ardern said to not act would cost even more than what would be spent on trying to eradicate it - $886 million.
"We have this one shot to eradicate, and we are taking it together.
"We want New Zealand to be free of it," Ardern said.
She said New Zealand had some factors that made it possible for it to be the only country to ever eradicate the disease - it was early in the outbreak, New Zealand had natural borders, and there was only one strain identified so far.
The Government will meet 68 per cent of the cost and Dairy NZ and Beef and Lamb New Zealand will meet 32 per cent.
After depopulation, farms will be disinfected and lie fallow for 60 days after which they can be restocked.
About 4.2 million cattle are slaughtered annually in New Zealand, this includes 1 million dairy cattle, 1.4 million beef cattle and 1.8 million calves.
High-risk animal movements have been traced to 3000 farms.
AT A GLANCE
• Mycoplasma bovis is a bacterium that causes udder infections (mastitis), abortion, pneumonia and arthritis.
• It does not infect humans and presents no food safety risk.
• The disease was first confirmed on one of South Canterbury Aad and Wilma van Leeuwen's farm on July 21 2017.
• In November last year the first major cull of livestock from infected properties occurred, with 4000 cattle killed, many of them off farms owned by the van Leeuwen.
• Prime Minister Jacinda Ardern announces May 28 more than 150,000 cattle would be destroyed in an effort to rid the disease from New Zealand.
• The current number of 'active' Infected Properties, quarantined and under movement restrictions as at 24 May 2018 is 37.
• Cattle will be disinfected and lie fallow for 60 days after which they can be restocked.
