A farmer in Victoria's Yarra Valley claims to have grown one of the largest truffles in the world, weighing in at a hefty 1.5 kilograms.

Stuart Dunbar said the truffle could fetch up to $3,000 on the wholesale market.

He said the initial discovery was made by his truffle dog, Lani.

"With the high temperatures of last Thursday of 21 degrees [Celsius], the dog and I were passing through, putting extra soil on them to insulate them when she [Lani] said: 'Hey boss have a look at this one, this is ready now'".

"We dug and we dug and we dug and 45 minutes later unearthed this massive truffle."

Stuart Dunbar says the giant truffle could fetch $3,000. ( ABC News: Joel Murugiah )

Mr Dunbar said the truffle was air dried overnight before it was weighed.

"When the scales clicked up 1.5 kilos, I thought I better go and get my camera and record myself weighing this," he said.

"On a plate, anywhere between three to five grams makes an unforgettable meal experience.

"I think that 300 people could have an unforgettable meal off a truffle that size."

Mr Dunbar said he has grown a lot of large truffles over the past year, but 1.5kg was by far the biggest.

"The size has been increasing year by year, there's been a few truffles this year around 500, 646, 800-gram size," he said.

"There was a couple at 1.1 kilos last year, but the weather and the bugs got to those before I did unfortunately."

Rather than sell the delicacy, Mr Dunbar said he would preserve the truffle in alcohol as it would be difficult to sell to restaurants because of its size.

The world's largest white truffle, which weighed 1.89 kilograms, was sold at auction for more than $70,000 in the US in 2014.

The White Alba truffle was unearthed in the Umbrian region of Italy.