"This has to be the work of someone who doesn't like me, to make me look like I don't know what I am doing. But I've been doing this for 36 years and have never come across a situation this bad," he added.
"A tractor hadn't been in there because in March my team picked and dropped little gold kiwifruit on the ground, which have not been disturbed. Therefore, whoever's been here did it with a knapsack spray. They know the industry, they know the system. This is threatening my livelihood, and I am taking it very seriously. This kind of behaviour cannot be allowed to be tolerated."
He had lodged a complaint with the police, who he said needed a witness or someone who the guilty party had spoken to about the sabotage to come forward and give evidence. Mr Farrand believed he knew who was responsible, saying he had plenty of circumstantial evidence but not the hard evidence that the police needed to lay charges.
Senior Constable Robert Drummond said investigations were ongoing, and he hoped the $50,000 reward would help lead to an arrest and conviction.
"We're dealing with a large amount of money he's lost as a result of this incident, and we're obliged to pursue his complaint," he said.
Mr Drummond added that the most appropriate charge, under the Crimes Act, would be contamination of food or crops, which carried a maximum penalty of 10 years' imprisonment.
A Zespri spokeswoman said fruit from Mr Farrand's orchards had failed multiple residue tests, recording many times over the allowed limit set by the government.
"We acknowledge the difficult circumstances for this grower," she added.
Any information can be given to Mr Farrand (phone (022) 391-8772, email kafarrand@gmail.com), or to Mr Drummond at the Kerikeri police station, phone (09) 407-9211.