"Orchards in this area are cheek by jowl, but we are able to identify a single site where the PSA originated."
The orchard and bee pollen operation he singled out was Kiwi Pollen, owned by Jill Hamlyn and Graeme Crawshaw, he said, who got a PSA-infected shipment of pollen from China.
"It was not a difficult task to follow the arrows once the shipment was back in New Zealand."
Salmon said New Zealand's ministries were crucial to protecting growers and natural heritage.
"Any invasion by pests have calamitous results and we are faced with a case where it [protection] went wrong."
Salmon said kiwifruit and wine are New Zealand's top two exports, with the former worth $1.3 billion each year.
MPI denies all the claims, including that it has a duty of care.
The hearing is expected to last for 12 weeks.