Arbor Digest

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Arbor Digest

The Mounts Iconic Norfolk Island Pines in Decline
17 April 2014

The Mounts Iconic Norfolk Island Pines in Decline

 

Over the last 12 months many of the Norfolk Island Pines have been showing signs of decline. Many of the trees along Pilot Bay and Marine Parade have been showing symptoms of disease or severe stress.

Arbor Care collected soil and foliage samples for SCION to test. Scion is the leading Crown Research Institute in forestry biosecurity, risk management and mitigation. This initial testing identified Phytophthora multivora from the soil and fine roots.

Phytophthora is a well-known root pathogen species that contribute to and often drive tree declines worldwide. It is often however not the primary cause of tree decline.

Following the identification of Phytophthora SCION has initiated a trial on these trees treating a number of them with a combination of phosphite injections and micronutrients. This trial will be ongoing over the next year or more.

Scion has since had some discussions with Gerald Collett (an Arboricultural Consultant from Auckland with a keen interest and knowledge of Norfolk Island Pine Decline) and Arbor Care have assisted SCION to collect more samples from declining and healthy trees to be tested for a Phytoplasmid. Similar symptoms have been observed in trees in India which have been shown to be caused by a Phytoplasmid. At this stage there is no proof that these symptoms are caused by this type of organism; however, SCION feel it is defiantly worth checking if this could be a cause in this case.

This testing and trials has not yet given an answer as to what is happening with these trees but the analysis is ongoing and will hopefully come up with an answer and treatments before we lose to many of these Iconic trees along the beach front.

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