Two multi millionaire businessmen are putting up almost half a million dollars to preserve the Kauri tree.

It's being threatened by a dieback disease and Sir Stephen Tindall and Julian Robertson and contributing the money through their foundations to fight the threat.

$100,000 a year for the next three years will go towards landowners' efforts to stop livestock spreading the spores which infect Kauri on their land.

It'll also fund public education and practical efforts such as hygiene stations at track entrances.

A further $60,000 a year will be used to support local kauri protection groups.

Conservation Minister Maggie Barry has thanked the pair for the donation.

Sir Stephen said kauri are a national treasure, an iconic part of our landscape, and unless urgent action is taken they could be wiped out.

Their contribution comes on top of more than $26 million in the last Budget set aside for fighting the disease.