The outbreak of the myrtle rust disease is having an effect on Arbor Day, which is celebrated on June 5.
Conservation organisation Project Crimson asks groups in Waikato, Northland and Taranaki region not to plant any myrtle plants at any planting days until the disease is declared to be eradicated.
The trust says this year, it is important to keep track of all planting.
"For all other plant species, it is advisable to ensure the nursery of origin has been adhering to the NZPPI hygiene protocols and that you keep a record of the number of plants by species, their origin and planting location, as these plants can still be a vector."
It says that planting of myrtle species may be done if plants are not sourced from Northland, Waikato or Taranaki.