The number of properties around the country infected with myrtle rust now stands at 20.
Sixteen are in Taranaki, three in Northland and one in Waikato.
The Ministry for Primary Industries said the affected sites were a mix of nurseries, private gardens, retailers, distributors and an orchard.
The rust has so far been found on pōhutukawa, ramarama, mānuka, eucalyptus and monkey apple.
The ministry said it was getting unprecedented support from members of the public in its effort to control the disease, with well over 450 reports of suspected symptoms to its 0800 number.