Zebra chip (Candidatus Liberibacter solanacearum)

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PLANT PEST

Zebra chip

Exotic to Australia

Life form: Bacterium
Origin: Mexico
Distribution:USA, Canada, Mexico, Guatemala, Honduras
and New Zealand
Features:Yellowing, stunted or abnormal growth, ulcers,
wilting of leaves
Pathways: Imported plant propagative material, insect vectors
At risk: Horticultural crops eg. carrot, capsicum, potato, tomato


Zebra chip is a disease complex caused by the bacterium ‘Candidatus Liberibacter solanacearum’, and poses a threat to important horticultural crops. Its name comes from the characteristic dark stripes that it causes in potato.

Impact of the disease is closely associated with the presence of the insect vector, the tomato-potato psyllid (Bactericera cockerelli) which spreads the disease between plants. The bacterium is very fragile and can only survive inside living host tissue.

See if you can identify the pest

Everyone needs to keep an eye out for symptoms of zebra chip and its insect vector.

Main symptoms of zebra chip are:

In all plants

  • yellowing and/or purpling of leaves
  • stunted or abnormal growth
  • stem canker (ulcers)
  • wilting of leaves.

In potatoes

  • dark blotches
  • stripes (making them commercially unviable).

In carrots and tomotoes

  • leaf curling
  • yellowing and/or purpling of leaves
  • stunting of roots.

In capsicum and chillies

  • leaves turn pale green or yellow with spiky tips
  • stunting of leaves
  • plant death.

The insect vector can be transported over large distances by wind currents. Zebra chip can be also be spread by:

  • infected plant material
  • seeds.

The insect vector tomato-potato psyllid (Bactericera cockerelli) is a sap sucking insect that resembles a miniature cicada. It grows to about 3mm long and is brown in colour with a broad white band on the abdomen.

Discolouration in potato tubers caused by Zebra chip (source Constable 2010)


A single slice of potato cut through the centre showing brown discolouration and stripes through the potato.
Shoots of potato plant infected with ‘Candidatus Liberibacter solanacearum’ showing curled, chlorotic and rolled leaves and aerial tubers (source Constable 2010)
There are red arrows pointing to particular parts of the shoots of the potato plant that are infected with the bacteria. It is showing curled chlorotic and rolled leaves and aerial tubers.
Tomato-potato psyllid (source: Plant Biosecurity CRC)
Tomato-potato psyllid is a small insect similar to a miniature cicada. It has a brown body with white or yellowish markings on the thorax, Wings are transparent and held vertically over the body.

Importers

If you work around imported plant material you need to look for insect vectors and be aware of import conditions applying to seed, vegetables and nursery stock.

Growers and home gardeners

Once potatoes are cut, the disease can be easily distinguished. If they are fried, striped patterns of discoloration will be evident in the potato tubers, and potato chips will also taste and look burnt.

Zebra chip can occur in:

  • celery
  • capsicum
  • carrots
  • eggplant
  • potato
  • tomato.

Zebra chip can also affect other solanaceous plants (such as nightshade) and  psyllid damage has been reported from sweet potato and kumara.

Protect your farm from biosecurity risks, practice good on-farm biosecurity and regularly monitor your fields.

Check what can legally come into Australia

All Australians and international tourists have a role to keep out exotic pests and diseases.

Zebra chip and its insect vector are present in a number of countries. Australia remains free of both the exotic vector and the disease-causing bacterium. We need your help to keep it this way.

Check what you can and cannot bring into Australia, whether you are a:

Don’t let our potato chips become zebra chips

Zebra chip has the potential to severely reduce the yield and quality of crops. Zebra chip has caused widespread impacts in both New Zealand and the United States, costing the international potato industry millions of dollars.

Import restrictions and biosecurity measures

Some items, by law, are subject to certain import conditions to be allowed into Australia. Please check the Biosecurity Import Condition System (BICON).

Be aware of any zebra chip and insect vector biosecurity measures that may be in place for incoming goods and conveyances. Industry advice notices are reviewed regularly and could change.

Secure any suspect specimens

Containment is critical. This could be as easy as bagging a suspect plant specimen that has symptoms or stopping an insect escaping by closing the doors on a shipping container.

Controlling vectors and removing infected plant material are the only control options, in conjunction with movement restrictions on infected plant material, to limit its spread.

Report detections of exotic pests

Any detections of zebra chip or its vector must be reported to the authorities.

Import community

If you receive or work around goods imported from overseas, including mail, you need to be vigilant to zebra chip symptoms and other exotic pests.

If you see an unusual pest, secure the goods to limit the movement of the pest and immediately report it to the Department of Agriculture and Water Resources SEE. SECURE. REPORT. Hotline 1800 798 636 or by using the online form.

Growers and home gardeners

If you see zebra chip symptoms or anything unusual, report it to the Exotic Plant Pest Hotline 1800 084 881. This will put you in touch with the Department of Primary Industries or agriculture in your state or territory.

When reporting your concern, you will be given advice on handling the specimen and what to do next until an officer can investigate.

Additional information

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