Myrtle rust, the lethal fungus that targets such iconic native species as pōhutukawa, rātā, kānuka, ramarama and mānuka, thrives in spring and could be set to spread further as it releases millions of microscopic spores in the warming weather.

The fungus has already been found in Northland, Waikato, Te Puke and Taranaki. It attacks plants belonging to the myrtaceae family, also known as the myrtle family and is found in many parts of the world including New Caledonia and all along Australia’s east coast.

Now is also the best time to spot myrtle rust. Symptoms to look out for on myrtle plants are:

• Bright yellow powdery eruptions appearing on the underside of the leaf (young infection)
• Bright yellow powdery eruptions on both sides of the leaf (mature infection)
• Brown/grey rust pustules (older spores) on older lesions
• Grey, ‘fuzzy’ spore growth on undersides of leaves

Some leaves may become buckled or twisted and die off.

If you think you see the symptoms of myrtle rust:

• Don’t touch it or try to collect samples as this may increase the spread of the disease
• Call the MPI Exotic Pest and Disease Hotline on 0800 80 99 66
• If you are able to, take clear photos, including the whole plant, the whole affected leaf, and a close-up of the spores or affected area of the plant

More myrtle rust photos…

Myrtle rust fungus – don’t touch, call MPI

Myrtle rust has now spread to sites from coast to coast in the North Island. Photo: MPI

Myrtle rust fungus