It's already December which means Christmas. Here in Aotearoa New Zealand, we like to do things differently. Christmas in the Southern Hemisphere is in the middle of summer. The heat of summer also means the flowers of the pōhutukawa.

 

Pōhutukawa or Metrosideros excelsa is a coastal evergreen tree in the myrtle family, Myrtaceae, that produces a brilliant display of red (or occasionally orange, yellow, or white) flowers, each consisting of a mass of stamens. It is one of twelve Metrosideros species, endemic (only found here in Aotearoa) to New Zealand. Renowned for its vibrant colour and its ability to survive even perched on rocky, precarious cliffs, it has found an important place in New Zealand culture for its strength and beauty, and is regarded as a rākau rangatira (chiefly tree) by Māori.

 

Myrtle Rust is a wind-borne fungal disease that can infect taonga species such as mānuka, pōhutukawa, and rātā.

The disease causes bright yellow-orange powdery pustules on young leaves, shoots, fruits and flowers of plants in the myrtle family.

 

This map shows, in green, members of the Myrtle or Myrtaceae family (including mānuka, pōhutukawa, and rātā) as identified by the iNaturalist app (citizen science app where the public can report observations of the natural world).

 

In red we see reports, in the iNaturalist app, of these Myrtle trees infected by Myrtle Rust.

 

Myrtle rust cannot be eradicated from Aotearoa. But there are things you can do to help us manage the impact and protect our taonga myrtle ngahere (the forest / trees):

Don't touch.
Don't collect samples as this might spread the disease.
If you can, take a photo of the rust and the plant it's on.
Report symptoms to the iNaturalist website or via the iNaturalist app available in your device's app store.
If you accidentally come in contact with the affected plant or the rust, bag your clothing and wash your clothes, bags and shoes/boots when you get home.
 

Global heating and climate change means that the humid and wet conditions that create the perfect habitat for Myrtle Rust to thrive - will only become more prevalent. We need to be on the lookout for these fungal threats as we venture out to our ngahere or forests over summer.

 

Additional fun information: Myrrh (more Christmas folklore - see gold, frankincense, and myrrh) is a gum-resin extracted from a number of small, thorny tree species of the family Burseraceae, and the genus Commiphora. A different family from the Myrtle or Myrtaceae family; similar spelling - different family.

 

Geography, digital geography has a role to play in the various outcomes of Climate Change, watch this space as new technologies and methodologies evolve in our ever-changing world.

– Matt Couldrey [geoid - digital geography]