WHAT IS KAURI DIEBACK?
Kauri dieback is the deadly kauri disease caused by Phytophthora taxon Agathis (or PTA). Following DNA studies, this fungus-like disease was formally identified in 2008 as a distinct and previously undescribed species of Phytophthora. Kauri dieback is specific to New Zealand kauri and can kill trees of all ages.
HOW DOES IT SPREAD?
Microscopic spores in the soil infect kauri roots and damage the tissues that carry nutrients within the tree.
Kauri dieback life cycle
The oospores are like the ‘seeds’ of this disease, with a hard outer shell they can sit dormant in soil for up to three years or more. These spores live in soil and are spread with soil movement. Dirty footwear, animals, equipment and vehicles are responsible for the large scale spread of this disease – between different areas of kauri.
The introduction of spores to an area of kauri can lead to a new area of infection. We don’t yet know what “inoculum load”/number of spores are required for an infection to occur – however, as the spores can reproduce/multiply once introduced to an area, a minute amount of soil with a tiny amount of spores can result in a new area of disease.
WHAT DOES IT DO TO KAURI TREES?
Microscopic spores in the soil infect kauri roots and damage the tissues that carry nutrients within the tree. Infected trees show a range of symptoms including yellowing of foliage, loss of leaves, canopy thinning, dead branches and lesions that bleed gum at the base of the trunk.
Some infected trees can show canopy dieback and even be killed without any gum showing on the trunks as kauri dieback also acts as a severe root rot below ground.
Nearly all infected kauri die. In the past 10 years, kauri dieback has killed thousands of kauri in New Zealand.
Scientists are currently working to find control tools for this disease but there is no known treatment at this time.
PREVENTION – What can I do to save our kauri forests?
Without any treatment or control tools, the only way we can save our kauri forests is to contain the disease in its current locations and stop the spread into healthy areas
When you are around kauri:
- Make sure shoes, tyres and equipment are cleaned to remove all visible soil and plant material before AND after visiting kauri forest
- Please use cleaning stations installed on major tracks: scrub to remove all soil and spray with disinfectant.
- Stay on the track and off kauri roots
- Keep your dog on a leash at all times.
We all can help – tourists, hunters, trappers, trampers, runners, bikers, walkers. We all need to make it happen, rather than hope ‘someone else’ will do it.
Read more here on how to stop the spread (170.6 KB PDF).