Police allege the Barretts then placed the tree in the rear of the ute.
"As they drove past the defendant's house towards the main road, the defendant shot at their vehicle with a high powered .177 calibre Stoeger air rifle."
The documents stated Nuku told police he had shot at the vehicle to mark it so he could identify it later.
In court Nuku, representing himself, said the shots were not reckless and he was protecting his property.
"He was out stealing my stuff... stealing a tree off my neighbours. I fired it to protect my property," Nuku said.
"It's cost my family more than it's cost theirs," he said. "The police refuse to arrest them because of who they are."
Nuku was convicted and remanded to appear for sentencing on May 24.