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New bacterium affects fresh tomatoes and capsicums

4 June 2008

New bacterium affects fresh tomatoes and capsicums

MAF Biosecurity New Zealand (MAFBNZ) has today withdrawn phytosanitary certification for New Zealand fresh tomato and capsicum export produce until further notice, following the confirmation of a new disease-causing bacterium in three commercial hot-house operations in the North Island.

MAFBNZ Director Border Standards Tim Knox says the withdrawal of phytosanitary certification is a pre-cautionary measure until more information about the bacterium is available.

Mr Knox says little is known about if or how the bacterium may have entered New Zealand, or its transmission, effect, and distribution –“we have initiated a programme of research to answer these questions. The results, of this research, will help determine the feasibility of options for managing the disease.

“Initial findings suggest that the bacterium may be transmitted by a small insect called the tomato/ potato psyllid - there are no considered human health issues associated with the bacterium or with eating tomatoes or capsicum.”

Mr Knox says MAFBNZ is working closely with Horticulture New Zealand and sector representatives from the fresh tomato and capsicum industry to discuss the situation and consider possible response options.


Q & A’s for a new tomato bacterium

How did MAFBNZ identify this new-to-science bacterium?
Due to the similarity of symptoms to a number of tomato plant diseases, identifying the bacterium through extensive testing was a challenging exercise conducted over several months. This has resulted in the development of a specific and sensitive test that enabled MAFBNZ to identify the bacterium.

How does the bacterium affect the crops?
This is a new-to-science organism about which little is known. The bacterium affects both the growth and quality of plants and reduces yield. Symptoms in both tomatoes and capsicums may vary across varieties and growing conditions e.g. glasshouse/field grown.

Symptoms in tomatoes include leaf curling and yellowing, stunting of the plant, fruit occasionally misshapen with a strawberry-like appearance. The leaf stalk may also become very long and fruit development may be uneven.

Symptoms in capsicums include pale green or yellow leaves with spiky tips. Leaves may be misshapen, leaf stalks appear short, flowers may drop and plant top may die back.

Does the bacterium affect the fruit as well as the plant?
Yes – both the plant and fruit can be affected. The bacterium has been detected in the tomato fruit itself, which is the part we export, as well as leaves and stem. Fruits showing no symptoms of the disease can be infected. There are no human health risks to known to be associated with the handling or the consumption of affected fruit.

Are there any human health risks?
There is no human health risk known to be associated with consumption of affected fruit.

How is the disease spread?
The disease is insect-vectored or graft-transmitted and initial findings suggest the bacterium may be transmitted by a small insect called tomato potato psyllid which is widespread throughout New Zealand.

What is a psyllid?
Psyllids are small insects which resemble miniature cicadas – they are 3-4mm in length with clear, elongated wings.

How will this disease be controlled – how widespread is it?
We have three confirmed sites - all are in the North Island. Control measures are likely to be difficult as the vector is mobile, already widespread in glass house and outdoor crops, and has already been recorded in the affected crops.

What is the host range – what crops could be affected?
Known hosts at this stage include tomatoes and capsicums but because the disease is new to science the full host range is yet to be determined.

How did the disease get here?
We may never know.

Will movement controls be put in place?
Because symptoms have been present for several months and glasshouse tomatoes are considered high health production systems, with strict hygiene procedures, no urgent measures are planned, or have been undertaken to date.

How will this affect exporters?
This is a significant find which could impact on our export markets. We have met with the growers concerned and industry to share and obtain more information. We have also notified our trading partners. MAFBNZ stopped issuing phytosanitary certificates from 4 June 2008 as an interim measure until we have more information on the bacterium. The withdrawal of export certification is an immediate, interim precautionary measure until more information is available on the biology and distribution of the bacterium in New Zealand.

How much are the tomato and capsicum export market worth?
Total exports of tomatoes are valued at $7.3 million per annum and capsicum $34 million per annum so the market is considerable. At this time of the year exports of tomatoes and capsicum are negligible – these usually begin on a large scale in October.

Where do we export tomatoes and capsicums – which countries?
Australia is our largest importer of tomatoes and capsicum. We also export capsicums to Japan, the Pacific Islands, United Arab Emirates and Hong Kong.

Will MAFBNZ be carrying out further research on this bacterium?
Yes – there is more research to be done as little is known about how and when the bactrium entered New Zealand. Moreover, how the bacterium is transmitted and it’s full effect on tomato and capsicum crops are also yet to be determined. Further research will also determine the feasibility of a range of management options and will ensure trading partners are well informed before the export season begins in October.

What should growers do if they find something unusual fitting the description of the bacterium in their crops?
They should bag plant parts with symptoms (plastic bag) and package into a non-breakable container and mail to:
MAF Freepost 120201, PO Box 2095, Auckland 1140, Attention: BLO
Include fruits (1 or 2), old leaves and stems.
• Include contact address and variety of crop
• State the date the sample was collected
• Include photo of symptoms (if possible)
Other information which would be useful includes; state when symptoms were first detected and the presence of psyllids on or around the crop.
Please note samples should not be sent on Friday, Saturday or Sunday as the testing facilities do not normally operate over the weekend.
For those wishing to courier samples at their own expense, send to:
MAF, 231 Morrin Road, St John, Auckland, Attention: BLO.

Or call MAFBNZ Pest & Diseases free phone on 0800 80 99 66

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