The myrtle rust outbreak is continuing to spread, particularly in the Taranaki region, with a further five properties found with infections this week.
The latest numbers stand at 29 properties in Taranaki, three in Northland and two in Waikato.
The species affected so far include pōhutukawa, ramarama, lophomyrtus, eucalyptus, mānuka and monkey apple.
The Ministry for Primary Industries said while most of the infections have been found on young seedlings, rust was now appearing on big, established trees in a number of places.
It said anyone with a suspected sighting should immediately get in touch.
The ministry advised gardeners to avoid planting any species susceptible to myrtle rust, particularly in those areas already affected by the disease.