AUGUST 2007

Inishowen Gardeners to be aware of Sudden Oak Death

The disease Phytophthora ramorum, which causes Sudden Oak Death, was discovered in a rhododendron in a private garden on the outskirts of Derry city, and the Department of Agriculture and Rural Development in the north says they believe they have stemmed the outbreak. The disease is related to potato blight and has caused woodland devastation in other parts of the world. Sudden Oak Death has been found in may European countries including England, Wales and Ireland, but has previously only been seen locally on imported plant material.

Ralph Sheppard, wildlife consultant, said the disease has not yet caused serious damage on this side of the Atlantic, but "in native oak forests in California it has wiped out a sizeable percentage of trees. It is seriously devastating". The U.S. Department of Agriculture Forest Service says that since 1995, tens of thousands of oak trees have been killed by the disease, primarily in California but also in southwest Oregon.

Ralph said the disease can also be found in alien shrubs, such as rhododendron, but "If it did get into oaks then it really would be a serious matter." The fungus Phytophthora ramorum, has the potential to attack a wide range of woody plants including rhododendron, viburnum and certain species of trees including beech.

The Northern department of agriculture took steps to contain the outbreak, including requiring the destruction of the diseased plant and monitoring the area surrounding the site. A northern agriculture department spokesman said this marked the first time this disease has been found in Northern Ireland outside of a plant nursery. "It is important that the disease does not establish in Northern Ireland, as it has the potential to cause significant damage to trees and landscapes," the spokesman said.

The department said the first indication of the disease on rhododendron is wilting of shoots. Affected shoots will develop a brown to black colour that spreads along the twig and can move into the leaves, causing the leaf bases and tips to blacken. Leaf infection can also occur without twigs being infected. On trees the disease can affect just the bark or can affect leaves as well. Symptoms in beech are bleeding cankers on the bark.

For more information visit the agriculture department web site at www.defra.gov.uk/planth/pestnote/newram.pdf.

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