Kauri Dieback

Dead Kauri ( Kauri dieback) showuif wide sptread bracnhs on top of the trunk

Phytophthora agathidicida – Kauri Dieback

Kauri dieback is killing some of the most ancient trees in the world.

Kauri Dieback is now the only major threat to the survival of Kauri trees. With the end of Kauri tree logging and the protection of many large tracts of native forest,

Kauri tree ancestors appeared in New Zealand 190 to 135 million years ago. They have survived ice ages, mankind and everything else nature has thrown at them so far. It would be a terrible thing to lose them now because of a single disease.

Everyone supports defending our Kauri trees – see here

There is no Kauri die back in the Tangihua’s yet.

There are thousands of Kauri trees in the Tangihua Ranges, including some impressive specimens that can be found at the end of the Kauri Grove Walk.

There is No cure for Kauri Dieback – Prevention is the only option

Once Kauri Dieback has entered an area there is no proven way to remove it. The only way to protect the Kauri trees is to ensure that Kauri Dieback does not enter the forest.

Animals such as pigs and goats spread the spores between areas of Kauri within a forest but is people with dirty footwear, equipment and vehicles that are responsible for spreading the spores between different Kauri forests.

All people entering the Tangihua Ranges must clean and disinfect their footwear, even if it is not being worn at present and is in a pack or bag

There are a few easy things you can do to help stop the spread of Kauri Dieback and protect our native giants:

• Clean and disinfect your shoes and equipment before and after entering kauri forest areas.
• Keep to the marked tracks.
• Stay away from Kauri tree roots as much as possible.
• Do not take vehicles off the road.
• Clean and disinfect bikes before arriving.

The Skeleton of a large kauri destroyed by Kauri Dieback

What is Kauri dieback

Kauri dieback

is fungus-like disease caused by Phytophthora agathidicida. It was formally identified in 2008 and is specific to New Zealand Kauri and kills Kauri trees of all sizes and ages.

The micorscopic spores of Kauri Dieback live in the soil and can be transferred with soil stuck to shoes, gear (tent pegs) or vehicles.

How Kauri dieback effects our Kauri Trees

Kauri Dieback damages the tissues that carry nutrients through the tree. Infected trees often have numerous ‘wounds’ near the base of their trunks that leak gum. These wounds usually form a circle around the trunk and the parts of the tree above these are starved of nutrients.

Infected trees show a range of other symptoms including yellowing of foliage, loss of leaves, canopy thinning and dead branches

Kauri dieback life cycle

Kauri dieback has four distinct stages and effect Kauri in 8 steps

1. Oospores (resting spores) are introduced into an area of kauri
2. Oospores germinate to form sporangia
3. Sporangia produce zoospores
4. Zoospores are released during and immediately after heavy rain
5. Zoospores (mobile spores) swim through soil-water to kauri roots, attach to the root surface, germinate to produce mycelia which infects the kauri root
6. The organism grows through the root system to affect tissues at the base of the trunk (damaging tissues that transport nutrients and water to canopy)
7. More sporangia are formed from areas of infected root…..which release more zoospores during/after heavy rain
8. Oospores form within infected tree tissue and are release into the soil as tissue decays

The oospores are like the seeds of this disease. They have a hard outer shell and can sit dormant in soil for three years or more. This why we must prevent soil entering the ranges

Dirty footwear is a major issue which is why we have cleaning stations at the gate and the lodge which must be used.

References

Rachael Mannion

• www.kauridieback.co.nz
• Kauri park nurseries website – photo
• DOC
• Northland Regional Council

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