Farm Forestry New Zealand
PESTS AND DISEASES OF FORESTRY IN NEW ZEALAND
Pine pitch canker: The risk to New Zealand
Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.
From Forest Health Newsletter No. 58, November 1996.
As part of an analysis of the risk posed to plantation forestry in New Zealand by the pitch canker fungus (Fusarium subglutinans f. sp. pini) a survey of the incidence and severity of the disease was carried out in selected roadside plantings. parks, natural stands and Christmas tree plantations of Pinus radiata in California. The incidence of the disease in roadside trees varied from 28% to 74% and in parks from 6% to 73%. However, these figures underestimate the real incidence because in many areas trees killed by the disease had already been removed. New Zealand's plantations have originated from the Ano Nuevo and Monterey Peninsula stands of P. radiata and the effect of the disease in these areas was of particular interest. Fifty six percent of the trees assessed in the Ano Nuevo stand had some dieback whereas trees in the Del Monte forest at Monterey were almost completely free of disease. In the Christmas tree plantation assessed mortality amounted to 13%.
A number of potential pathways for the entry of the pitch canker fungus into New Zealand were recognised. These are Pinus seed, plant material associated with used logging machinery, timber used as wood packing and bark and twig insects which have been shown to transmit the disease in North America. The probability of establishment for each of these pathways was calculated, except for the insects for which insufficient information was available. Used logging equipment and seed had the highest probability of establishment whereas packaging timber had the lowest. Even if the disease became established in New Zealand its spread is likely to be limited by the paucity of suitable insect vectors.Hylastes ater; Hylurgus ligniperda and, to a lesser extent, Pineus laevis appear to be the only likely candidates. The importance of airborne infection is problematic as it appears to play no part in disease spread in California whereas it is a major source of infection in the southeastern United States. New Zealand's response to the threat was discussed at the workshop held on 4 November at FRI. A proposal to test offshore the susceptibility of the top breeding material currently employed in New Zealand was considered at length. Other matters raised included a call for a voluntary halt to the importation of Pinus seed from those parts of North America known to have pitch canker, the need to clarify the potential role of airborne infection and the need to determine the survival of the fungus on its insect vectors and in timber. No final decisions were made by the workshop and the development of a strategy for dealing with the threat was deferred to the Committee of the Forest Health Collaborative.
(Margaret Dick, FRI)
This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)
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