Although a recent scare of myrtle rust in the Manawatu Gorge got the all clear, Horizons Regional Council and the Ministry for Primary Industries (MPI) are warning the public to be vigilant.
Myrtle rust is spread through airborne spores and can kill affected plants in the myrtle family, such as pohutukawa, manuka and feijoa.
Infections were first detected in a Northland nursery in May and there have since been 41 confirmed cases in the North Island -- 35 of those in the Taranaki area.
After a possible sighting of myrtle rust in the gorge late May, MPI ran tests that proved negative. However, myrtle rust spores are microscopic and can easily spread across large distances by wind, insects, birds, people or machinery.
Horizon's biodiversity, biosecurity and partnerships manager Rod Smillie says it's important those who find signs of myrtle rust, do not touch the infected leaves. Instead they need to call the MPI response team to lessen spread of the disease.
"The process requires suiting up and checking every leaf before decontaminating themselves to ensure no potential spores are transferred when they move to the next property," he said. "With numerous plant species susceptible to myrtle rust, it's a very thorough operation."
Myrtle rust can be identified as bright yellow powdery eruptions appearing on the underside of the leaf for a young infection, both sides of the leaf for a mature infection and brown/grey rust spores on older lesions.
"Myrtle rust generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers and fruit," Mr Smillie says. "If you think you've seen the symptoms of myrtle rust, do not touch it, call the MPI exotic pest and disease hotline immediately."
MPI suggests those who suspect an infection of myrtle rust use a camera or phone camera to take clear photos, including the whole plant, the affected leaf, and a close-up of the affected area of the plant.
Information on myrtle rust can be found at mpi.govt.nz/protection-and-response/responding/alerts/myrtle-rust.
Suspected myrtle rust infections should be reported immediately to the MPI exotic pest and disease hotline on 0800 80 99 66.