A formal warning has been issued to 26 kiwifruit growers for misusing an antibiotic spray in their fight against the Psa vine disease.
An investigation by the Ministry for Primary Industries (MPI) found a chemical spray called streptomycin had been used illegally on 45 different orchards.
MPI compliance director Dean Baigent said the ministry had been mindful throughout the investigation that New Zealand kiwifruit growers were facing a desperate situation with Psa.
"The growers concerned voluntarily disclosed their wrong-doing and those who misused product on a larger scale sustained the largest losses through the disposal of their affected crop."
A formal warning letter was an appropriate conclusion to the investigation and any future breaches of the Agricultural Compounds and Veterinary Medicines (ACVM) Act 1997 would result in prosecution, Baigent said.