About 100 people went to Wednesday's Ministry for Primary Industries information roadshow at Papakaio, one of dozens being held throughout New Zealand.
''Stand up and make it happen,'' he said.
''It can't be farmer against farmer. Work with your neighbours, don't shame or ostracise them.''
Ministry response incident controller David Yard said there had been ''ridiculous reactions'' when people had found out who was involved - a cattle sale was cancelled after a farmer's stock was blood-tested, contractors refused to go on to some properties, and children were bullied at school.
Waimate grazier Martyn Jensen stood up and announced he was ''farm number 39'' in the outbreak.
''I'm doing this reluctantly,'' he said of speaking out.
''If you want to make a difference, you have to communicate. There's no way around it.
''Unless you want to draw this out for bloody years, you have to talk.
''I told our neighbours. Some were pleasant, some were bloody horrible.
''There are a lot of things happening that are not pleasant.''
Mr Jensen said he did not blame affected people for ''shutting up''.
''We need your support,'' he told the meeting.
''Otherwise we all walk away and control it ourselves. Are you willing to do that?''
Applause erupted in the hall.
''I couldn't have said it as well as that,'' Mr Smith said.
''We're here to try and help you. Be open; talk about it.''
Maheno farmer Kerry Dwyer, one of the first to have his livestock test positive for M.bovis, said those affected would lose time, sleep, stock, money, and friends.
He knew of people who had shot animals because they could not stand the hassle of the official eradication process.
Mr Smith said if anyone was stupid enough to do that, they deserved what they got when ministry officials turned up at their farm.
''Biosecurity only works if you are open and honest.
''Step up, do what's right, and we'll try and do what's right by you.
''Don't try and hide it. Your elected officials have made the decision to give eradication a shot. The only way it will work is if we all pull together.''
The outbreak could involve up to 190 properties out of the more than 20,000 dairy and beef farms in New Zealand, he said.
On Friday, the 92nd outbreak update from the ministry revealed another four South Island farms had been confirmed with M. bovis in the previous week: a Waimate drystock beef farm with 1339 animals; a Darfield drystock beef and sheep farm with 370 calves; a Tapanui beef farm with about 1000 animals; and an Invercargill beef farm with 25 calves.
All four farms were connected through animal movements to previously known cases.
Biosecurity Minister Damien O'Connor announced on Friday the ministry would advise farmers if neighbouring properties were infected or high-risk, and a list of National Animal Tracing System (Nait) numbers of affected animals would be published on its website.
