The plant disease myrtle rust has been found in the Auckland region for the first time.
The fungus harms trees in the myrtle family, including feijoas and native species such as pohutukawa, manuka and rata.
The disease was first discovered in Northland in May, and several cases have since been confirmed in Taranaki, Waikato and the Bay of Plenty.
The Ministry for Primary Industries said the latest find was at a commercial plant production site in Waimauku, where the rust had been found on hundreds of ramarama plants.
Response controller Catherine Duthie said a team had started to remove the infected plants and destroy them.
The team would also start checking neighbouring properties to identify any other potential infections.