New bacterium affects fresh tomatoes and capsicums

MAF Biosecurity New Zealand (MAFBNZ) has been alerted to the presence of an unidentified bacterium in three hothouses in the North Island. The bacterium has been detected in fresh tomatoes and capsicum.

The bacterium has been identified as a previously undescribed species belonging to the genus Candidatus Liberibacter. Tests have shown that it is not any of the currently known species in the above genus. There are no human health issues.

Further investigations are needed to determine how it is spread. Initial findings suggest the bacterium may be transmitted by small insects called tomato potato psyllid.

At present it is not known how or when the bacterium entered New Zealand or how it may affect production.

  • Symptoms in tomato plants: Include leaf curling and yellowing stunting of the plant, fruit occasionally misshapen with a strawberry like appearance. The leaf axial or stalk may also become very long and the fruit development may be uneven.
  • Symptoms in capsicum plants: Include pale green or yellow leaves with spiky tips. Leaves may be misshapen. Leaf stalks may be misshapen, leaf stalks appear short, flowers may drop prematurely and parts of the plant may die back. Symptoms may vary in severity between varieties.

MAFBNZ has begun research which will help determine the feasibility of options for managing the disease. As an interim immediate precautionary measure, MAFBNZ has stopped issuing phytosanitary certification for New Zealand fresh tomato and capsicum export produce (as from midnight on the 3 June 2008) until more is known about the bacterium.

Once more market information is available MAFBNZ, in conjunction with Hort New Zealand, will develop an interim compliance package to enable the certification of New Zealand grown fresh tomatoes and capsicum that have been inspected, tested and found free of the bacterium.

MAFBNZ has met, and 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. Industry has expressed strong concerns about the bacterium and has indicated its willingness to work closely with MAFBNZ to determine next steps.

What to do if you suspect you have the bacterium in your crop:

Bag plant parts with symptoms (plastic bag) and package into a non-breakable container and mail -

MAF Freepost 120201, P.O. Box 2095, Auckland 1140, Attention: BLO

  • Include fruits (1 or 2), old leaves and petiole.
  • Include contact address and variety of crop
  • State the date the sample was collected
  • Include photo of symptoms (if possible)
  • Other information: State when symptoms were first detected and presence of psyllids.

Plant samples should not be sent on Friday, Saturday or Sunday as testing is not usually carried out over the weekend.

For those wishing to courier samples at their own expense, send to:

MAF, 231 Morrin Rd, St John, Auckland, Attention: BLO.

Or for call MAF Pest and Diseases freephone on 0800 80 99 66

Map - Survey of Sites

This map summarises the results of the rapid and basic liberibacter survey carried out at a limited number of tomato, capsicum and potato sites across the country.

The location and widespread nature of the liberibacter distribution strongly supports the theory of tomato/potato psyllids (TPP) acting as a vector. As only a limited number of sites were sampled in each region, in some instances only one site, any region in which TPP is present, is also likely to have liberibacter present. In addition asymptomatic (healthy-looking) plants tested positive for liberibacter at some sites.

Tomatoes

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

Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium

Photos: Joe Tang and Lisa Ward, PHEL

Capsicums

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

Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium Tomato/capsicum bacterium

Potatoes

Symptoms in potato tops can include these being smaller than normal, yellowing and the tops can develop a scorched appearance before premature collapse.


It should be noted that plants affected by the bacterium can exhibit some, all or in some cases, none of the above. MAFBNZ is still investigating whether all of the above can be linked directly to the bacterium or may be the result of another influence.

Page last updated: 8 September 2009