September 5, 2003

The New Zealand Ministry of Agriculture and Forestry (MAF) is investigating a possible case of impatiens necrotic spot virus (INSV), a plant disease which primarily affects ornamental plants.

MAF received a report on 22 August 2003 when a positive test result for INSV was obtained from a freesia plant in a Canterbury nursery. MAF is currently awaiting test results to confirm the identification of the virus.

As part of its investigation MAF is now working with nurseries throughout the country to ascertain the spread of the possible virus and also to determine how the disease entered New Zealand. MAF is also investigating a case of this disease in an upper North Island nursery.

"INSV has a wide host range of well over 100 plant species, mainly ornamental plants rather than vegetables and is mainly a pest in glasshouses," said Barney Stephenson, MAF's, National Adviser Plant Pest Surveillance and Response.

"This virus is closely related to the tomato spotted wilt virus which has been present in New Zealand since 1968.

"INSV is an unwanted organism under the provisions of the Biosecurity Act 1993.

"Symptoms caused by INSV depend on host species, environmental conditions, nutritional levels and age and stage of plant development when infected. Symptoms can include black discoloration at the base of the leaf and stems, brown leaf spots and wilt.

"MAF will be working closely with industry groups on this investigation. The disease can be managed by planting virus-free stock, destroying plants that show symptoms and monitoring and controlling thrips (very small insects) populations," said Barney Stephenson.