Michael di Berardino (centre) with his wife Gemma and their four children Antonetta, Paul, Maria and Angelo.

A great-grandfather has died after having a fight, possibly over poisoned roses, with his elderly neighbour in Australia.

Michael di Berardino, 83, died on the footpath outside a Joffre Street home in Reservoir, Melbourne, about 1pm on Monday.

It's been alleged di Berardino's 90-year-old neighbour hit him over the head with an iron bar during the fight.

The neighbour was questioned by police, but released pending further inquiries.

"Investigators will await the results of a post mortem," police said in a statement.

Di Berardino's eldest son Angelo said he arrived at the scene to find his father lying on the ground with emergency services trying to resuscitate him.

Angelo said the 90-year-old man was spotted returning home with a bag of shopping shortly after allegedly hitting his father.

He said his father had been feuding with his neighbour for as long as the two had lived in Joffre Street.

"It has been ongoing for 46 years," he said.

'DECADES-LONG DISPUTE'

Neighbours knew of the decades-long dispute, which one man said started before the two moved to Australia from Italy.

Some described the 90-year-old man as a pest, who stole women's underwear from their clothes lines, peered through their bathroom windows, poisoned their plants, and had several restraining orders taken out against him.

Angelo said the dispute between his father and his neighbour had escalated previously.

"There has been restraining orders ... been to the courts," he said.

"I have even spoken to his daughter-in-law ... nothing happened.

The 90-year-old man has lived alone since his wife died, and has two sons.

On Monday afternoon, a black tarpaulin surrounded the area where di Berardino's body lay on the footpath, as grieving neighbours and family gathered to mourn the loss of a true "gentleman".

Di Berardini had four children and had recently welcomed the arrival of his 13th great-grandchild.

Angelo said he had received a call from his children saying his father was not well.

"My mum rang my kids, they rang me," Angelo said.

But it was too late by the time he arrived at the home where his father and mother had lived for more than 40 years.

'KINDEST MAN IN THE WORLD'

As evening came, family and friends gathered in the front yard of the di Berardinos' low-set, brick veneer home.

Angelo described his father as a loving head of the family, who had a great sense of humour.

"He was a sh..-stirrer, a big one," Angelo said.

"He loved to drink, he loved to dance.

"You could tell him anything."

A good handyman, di Berardino happily helped his neighbours.

"The neighbours, if they had anything broken, he would repair it for nothing. He was the kindest man in the world," Angelo said.

He said his father came to Australia at the age of 19 from Abruzzo in southern Italy.

He said di Berardino went back to Italy seven years ago and still had family back home.

Son Paul said his father was a "strong man" who could be a "pain in the arse", but someone who helped his sons when needed.

"He had a sarcastic sense of humour," Paul said.

"He will be greatly missed."

Family friend, Jenny Tully, said di Berardino was very fit for his age and was in good health.

"He was very strong," she said.

"Here one day, gone the next."

Aniello Papa had lived opposite the two men for more than four decades. He described di Berardino as an "absolute gentleman" who helped everyone.

"I knew him very, very well," Papa said.

"He attended my father's funeral."

Frank Parisi, whose mother-in-law lived on the same street and was at home when the fight happened said he got a call from his wife about 2.30pm.

"'You better go and check my mum' [she said]. I said 'why?' She said, 'Mick is dead'."

Parisi said his mother-in-law was very close to di Berardino.

The homicide squad was investigating.

Victoria Police spokeswoman Belinda Batty said the exact circumstances surrounding the man's death were yet to be established.