A total of 156 cases of myrtle rust have now been found in the Bay of Plenty.
The Ministry for Primary Industries released the figures to the Bay of Plenty Times yesterday, revealing most cases have been found in Te Puke (43), Bethlehem (29), Tauranga (17) and Rotorua (10).
A spokesman said Bay of Plenty was one of the worst affected areas in New Zealand and people needed to take care not to spread the tropical fungus and to check their local myrtle plants.
The Department of Conservation warned myrtle rust posed a threat to New Zealand's iconic Christmas tree, the pōhutukawa, because it was likely to be more active during warmer weather.
New Zealand's precious native myrtle plants including pōhutukawa, rātā, mānuka, kānuka and ramarama are vulnerable to the disease.
The fungus, mainly spread by wind, generally infects shoots, buds, and young leaves of myrtle plants. Infected plants show typical symptoms including bright yellow powdery spots on the underside of leaves.
If symptoms of myrtle rust are present the public is reminded not to touch the plant or collect samples, but take pictures and report it to Biosecurity New Zealand's Exotic Pest and Disease Hotline on 0800 80 99 66.
Nationally, 811 properties have been identified as being affected by myrtle rust.