The Korea - New Zealand free trade agreement was signed in Seoul yesterday and over time it will eliminate tariffs on New Zealand exports which at present at about $229.
Kiwifruit growers pay a 45 per cent tariff which will be phased out over five years and avocado growers a 30 per cent tariff
Which will be phased out over nine years.
Mr Osborne said Northland produced 37 per cent of the country's avocadoes and it was a big centre for kiwifruit and dairy production, all of which supported significant job numbers in the region.
"Yesterday he was promoting a referendum on legalizing cannabis and then withdrawing it an hour later. Today who knows what he'll promise but it's obvious he doesn't have Northlanders' interests at heart."
The deal was hammered out over five years and Trade Minister Tim Groser conceded it was a very difficult negotiation. Products exempted from tariff elimination include milk powder, frozen squid, fresh abalone, and frozen and unprocessed deer velvet.
Mr Peters said the Government had done no favours to farmers with the free trade agreement (FTA) and to suggest otherwise was "plain politicking."
He said he was talking to farmers every day - "not parked up in a rarefied atmosphere to advance my political persona and making up stories as we go along".
"New Zealand deserved a far better deal from Korea because of our aid to them during the Korean War and our part in their bailout of the Korean economy during the Asian financial crisis of 1997, which I as Treasurer organized."
Mr Osborne also criticized a bill sponsored by a New Zealand First MP, Fletcher Tabuteau, which bans Governments from entering trade deals with an investor-state dispute procedure.
The Korea FTA has such a provision and Acting Prime Minister Bill English suggested that free trade legislation - which will be required under the Korea FTA - could be harder to pass if Mr Peters won Northland.
"If the elect Mark Osborne, there will be no trouble about it going through. If they elect Winston Peters they are taking a punt.
"Mr Peters is trying to have it both ways. He is going up there and saying he won't change anything but down here he is initiating a legislative process that points in the opposite direction," Mr English said.
In reality the legislation on tariffs related to the Korea FTA are likely to come up well before Mr Tabuteau's bill and Herald can confirm that National has the numbers to block his bill because at least 61 MPs, National, Act and United Future, will vote against the New Zealand First bill.
Meanwhile Environment Minister Nick Smith told reporters at Parliament that resource management reform would be a lot more difficult if National was depending on Mr Peters to get it passed.
"My previous experience in working with Winston previously is its pretty Machiavellian. It is pretty difficult to determine where he is and in my view it will compromise what will be a pretty important and good reform for New Zealand.
"He is hard work and unpredictable and there in no questions that if Winston wins the Northland by-election, resource management reform will be more difficult."
Dr Smith was referring to his work with Mr Peters from 1996 to 1998 when Naitonla and New Zealand First were in coalition.
There was no doubt that if National is not successful in the Northland byelection that the job of resource management reform was going to be more difficult.
