The young son of a Victorian farmer who saw his father shot dead in front of him after another man tripped on an eggplant while carrying a shotgun says he struggles to get out of bed each day since his dad's death.

Prosecutor Nicholas Papas QC struggled to hold back tears as he read the victim impact statement of Flavian Calandro, who was aged just 12 when his father David was killed on a farming property in Tatura in northern Victoria on February 18, 2017.

"Every day I think about my dad, wishing he was here to guide me … I will forever miss him," his statement read.

"I know I have changed since the day he died … I struggle to get out of bed to go to school because the vision of my dad has haunted me and always will."

Flavian's younger brother Anton spoke of missing his "nice, caring dad" and how since the shooting he has become scared when any stranger comes to his house.

The eggplant Angelo Russo claimed he slipped on. ( Supplied: Supreme Court )

Mr Calandro's killer, 55-year-old Angelo Russo, sat in the Supreme Court dock holding his head with one hand as the victim impact statements were read out.

He pleaded guilty to manslaughter and told police his shotgun accidentally discharged after he tripped over an eggplant lying on the ground on his Tatura farm.

"I've just tripped, [the gun] has hit the [car] window and bang — I'm quite sure I didn't have my finger on the trigger," Russo said to police.

"The eggplant was there, I tripped, I slipped on the eggplant."

Shotgun found to have faults, court hears

Mr Papas told the court Russo and Mr Calandro had been friends but the victim had accidentally run over Russo's farm dog.

"The crown alleges the accused was angry and approached the victim with a loaded shotgun closed," he said.

"He was an experienced shooter. He well knew what he should have done.

"He owed a duty of care... his conduct fell so far below the standard expected... that it warrants criminal punishment."

The shotgun was found to have a fault which made it go off without the trigger needing to be pulled. ( Supplied: Supreme Court )

Mr Papas said the weapon was later tested and discovered to have two significant faults which made it "inherently dangerous", including one in which the gun discharged if the muzzle was struck, without the trigger needing to be depressed.

He said Russo was aware two children were in the car with Mr Calandro and Flavian, who was in the passenger seat, suffered multiple lacerations from the shattered window and hearing damage from the shotgun blast.

"This is a serious example of criminal negligence manslaughter … the physical and psychological effects suffered by both children constitute an aggravated feature," Mr Papas said.

"They witnessed the violent death of [their] father and now experience emotional trauma. The consequences … are horrific indeed."

Russo has already served nearly 450 days in custody and is now awaiting sentencing.