PGG Wrightson says it is terribly disappointed it has put the arable farming sector at risk.
It has acknowledged it breached biosecurity regulations by transporting a delivery of contaminated imported red fescue seeds in an unapproved manner, which led to black grass seeds spilling off its truck throughout mid Canterbury.
Black grass is highly invasive, often herbicide-resistant and significantly reduces the yields of wheat, barley, rapeseed and other crops.
PGG Wrightson seed general manager John McKenzie says the company sincerely regrets the breakdown in procedures at its end that led to the incursion and it will do what it can to make things right.
He says the Ministry for Primary Industries released the seeds to it under bond so it could remove the problem seeds.
Mr McKenzie says any seed that is moved needs to be transported in an enclosed vehicle.
He says in this instance the seed was in secure steel bins the company uses for transporting all its seed between sites.
"What we didn't do is move those bins inside a covered vehicle, when the seed arrived at Methven we noticed there was some seed on the deck of the truck and all the seed after it was processed was weighed in and it was weighed out and we determined there was an amount of seed missing."
Mr McKenzie says there must have been air pressure or something which sucked some of the seed out of those bins.
Following the incident, Mr McKenzie says the company has carried out a thorough review of its processes.
PGG Wrightson imports red fescue to use in the turf industry on golf courses and sports fields.