A Victorian farmer accused of shooting dead a man in front of his two children says the gun accidentally went off after he tripped on an eggplant.

Angelo Russo, 55, is accused of fatally shooting David Calandro in 2017 during a dispute after Mr Calandro ran over Russo's dog at a Goulburn Valley farm.

"The shooting was an accident," defence barrister Patrick Tehan QC told a Victorian Supreme Court jury on Wednesday.

Mr Tehan said Russo was holding a shotgun and walking towards Mr Calandro's ute when he tripped on an eggplant and the gun went off.

"It (the gun) then went off without the trigger having been pressed," the barrister said.

Mr Tehan said a ballistics experts will give evidence about a fault with the gun's safety switch.

David Calandro. (Supplied) (Supplied)

In his police interview, Russo told investigators: "There was an eggplant on the ground there and my foot must have rolled on it."

"It happened in a split second ... it was like I was falling and it went 'bang'."

But the prosecution alleges Russo walked up to Mr Calandro on February 18, 2017 and deliberately shot him in the head because Russo was angry about his dog Harry being run over.

"Because this is such a serious case I won't make any jokes about it, but it will loom large, this eggplant," prosecutor Nicholas Papas QC said in his opening address on Tuesday.

Mr Calandro's two sons were in the car when the 43-year-old was fatally shot.

The eldest boy, 12 at the time, was sitting in the passenger seat next to Mr Calandro.

"It looked like he had splattered blood on his face," Vince Vigliaturo told the court.

Mr Vigliaturo said he was a friend of both Russo and Mr Calandro at the time of the shooting and had accompanied Mr Calandro to pick up some chillies from Russo's farm in Tatura.

Mr Calandro was approached by the accused after returning to his farm. (9NEWS) (Supplied)

As Mr Calandro was driving out of Russo's property, he swerved towards Russo's dog Harry, which was barking and running alongside his ute, to "spook him".

"And that's when it was accidentally run over," Mr Vigliaturo said.

Mr Calandro turned to Mr Vigliaturo and said "oops".

"He looked in the mirror and sort of shrugged it off," Mr Vigliaturo said.

But Mr Vigliaturo could see the dog was injured after looking in the rear-view mirror.

About 10 minutes later Russo rang Mr Vigliaturo, who was back at his farm.

"He was very upset. He said 'you f***ing c***, you rang over my dog and you didn't even f***ng stop'."

Mr Vigliaturo said Russo wanted to know where Mr Calandro was.

"Tell him to come back and look at what he's done to my f***ing dog."

Recorded evidence from Mr Calandro's sons will be played to the jury on Thursday.