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Cypress canker on Redwood

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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 News 87, July 1999.

A specimen of redwood, Sequoia sempervirens, collected from Amberley by Paul Bradbury, Forest Research Forest Health Adviser, was found to be infected with Seiridium unicorne, one of the cypress canker fungi. The symptoms on the specimen were of small branch cankers and dieback. This is the first record of the fungus on S. sempervirens though it was recorded on Sequoiadendron giganteum in Hastings in 1979, also causing cankers and dieback (Forest Research records). There have been no subsequent records on this host. The causal agents of cypress canker, S. unicome and S. cardinale , have been recorded in New Zealand on the coniferous genera and Calocedrus, Chamaecyparis, Cupressocyparis, Cupressus, Juniperus, Sequoiadendron, Thuja, Widdringtonia. They cause severe cankering often resulting in dieback and/or mortality of cypresses in New Zealand. Although the Forest Health Reference Laboratory frequently receives specimens of redwood exhibiting dieback it is usually species of Botryosphaeria and Phomopsis that are found to be associated with the damaged tissue. Both these genera contain pathogenic species but infections are often associated with already stressed tissues. As it is so unusual to find either S. unicorne or S. cardinale on redwood it would be interesting to see how widespread this host/pathogen relationship is by looking for any form of canker on redwoods that exhibit dieback. The cankers usually form on the stem below the dieback as the latter is often the result of fungal toxins transported up the affected stem. In this sample there was no resin bleeding associated with the cankers as would normally be seen with Cupressus species, and this may make it harder to identify in the field.

(Kiryn Dobbie, Forest Research)

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(Scion is the trading name of the New Zealand Forest Research Institute Limited.)


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