A plant disease only previously found in the upper North Island has made its way south and been discovered in a Hutt Valley garden.

The presence of myrtle rush in three ramarama plants was confirmed by the Ministry for Primary Industries on Thursday and incident controller Catherine Duthie says the plants are heavily infected.

"This new find, significantly further south of other known infection in the upper North Island, is very disappointing," Dr Duthie said.

Myrtle rust is a fungus that attacks myrtle species including pohutukawa, ramarama, manuka and rata.

Dr Duthie said ramarama and pohutukawa were the species most affected and the new discovery in Wellington meant new tactics may be needed for containing myrtle rust.

Plants infected with myrtle rust had their foliage sealed to prevent spores drifting, were removed and buried.

"All efforts to date have been to contain infection where it is found. However we have been planning for the possibility that it turns out to be widespread and are realistic that it won't be feasible to keep removing all infected trees found long term," Dr Duthie said.