The fungal disease myrtle rust has been found on plants in Wellington.
The infection, which can ruin native plants including pōhutukawa, ramarama, mānuka, feijoa and rātā, has been found on three plants in a Hutt Valley garden.
They are "heavily infected" according the Ministry for Primary Industries (MPI).
"This new find, significantly further south of other known infection in the upper North Island, is very disappointing," Incident Controller Dr Catherine Duthie said.
Myrtle rust was discovered on New Zealand mainland for the first time in May.
The disease was found on five pōhutukawa seedlings at a nursery in Kerikeri, and it's believed that wind carried the spores from Australia to New Zealand.
Touching the plant's infection will help spread the disease. Do not touch it. Wash any tools and clothing that may have come into contact with the infection, and report the infection to MPI on 0800 809 966.