Possible cure to 'incurable' Pierces' disease

Media Release 27/11/00

Possible cure to 'incurable' Pierces' disease

The so called 'incurable' Pierces' disease, ravaging grapevines in California and posing a biosecurity risk to New Zealand grapevines, could well be 'curable' thanks to new technology developed at HortResearch.

HortResearch scientist Adrian Spiers was in California two weeks ago to conduct trials using stem injection technology which could be used to control Pierces' disease. "We lead the world in this technology. We are confident we can come up with a solution for American growers," Dr Spiers said.

The New Zealand Government is currently being urged to ban imports of Californian table grapes because they could carry the glassy winged sharpshooter, an insect which is spreading Pierces disease so rapidly among Californian vines that the United States Government has allocated US$47 million to try and stop it.

While Dr Spiers believes HortResearch has a solution for the American grape industry, he said it would be undesirable if Pierces' disease was introduced into New Zealand. "It is better to keep the disease out because every disease costs."

Dr Spiers said Pierces disease is actually relatively straightforward to kill, with many chemicals potentially able to do the job. This could include simple compounds such as copper. He said the difficulty has been a lack of a suitable methods for injecting chemicals into grapevines for control.

Stem injection technology has been developed by HortResearch in conjunction with Chemcolour Industries New Zealand. Trials will take place in California starting in the new-year in co-operation with the University of California, Davis.

This technology was developed initially to control Silver Leaf which causes major loss of yield in New Zealand and Australia's stone and pipfruit.

Vines infected by Pierces disease develop withered leaves in late summer due to lack of water transportation. Dr Spiers said this scorched leaf symptom is useful for detection and if treated quickly enough, the plants can be restored to good health.

Dr Spiers said the New Zealand grape industry suffers a far more serious threat in the form of Eutypa disease. This disease affects vines over ten years of age and is found throughout most of the world including New Zealand. It stunts shoots and causes dieback on vines. He said trials are being conducted in New Zealand, Australia and America to develop suitable treatments for control of Eutypa. These will be delivered by the same stem injection technology used to control Pierces' disease however the compounds used will be different. Words 404

For more information contact: Dr Adrian Spiers HortResearch Palmerston North Tel: 06 356 8080, ext 7748. Home 06 357 0568 Fax: 06 354 6731 Email: aspiers@hortresearch.co.nz Caleb Hulme-Moir HortResearch Palmerston North Tel: 06 351 7000, ext 7728 Fax: 06 351 7038 Email: chulme-moir@hortresearch.co.nz

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