An aerial survey of Waikato later this month will check forested areas for signs of kauri dieback disease.
It will be the first time the land between Port Waikato and Kawhia across to Morrinsville has been checked for the disease.
An expert observer on the flights will be looking for yellowing kauri leaves, canopy thinning and dead branches.
Waikato Regional Council biosecurity officer Kim Parker said there was no evidence of the disease so far but there were cases to the north in the Waitakere Ranges.
She said as there was no cure for the disease, prevention was the only option for keeping the trees alive.