The boots and vehicles of a small invading army of seasonal workers could place Northland's $36 million kiwifruit industry at risk.
The region has been in lock-down for several months to try to keep out the kiwifruit vine disease PSA, which last year caused losses in other parts of the country estimated at up to 15 million trays.
Northland is now the only major kiwifruit growing area free of the disease.
The north's kiwifruit growers have united to voluntarily impose stringent hygiene regimes and movement controls on industry players to keep the region free of the disease, but say risk is ramping up again with hundreds of orchard workers due to arrive soon for the start of the picking season - many of them fresh from affected areas, like Gisborne, with earlier picking seasons.
Robbie Bell, chairman of the Northland committee of Kiwifruit Vine Health (KVH), says incoming workers and contractors will be heavily targeted with messages on disinfecting footwear, hands and machinery.