The Department of Agriculture, Western Australia has eradicated a case of potato spindle tuber viroid (PSTVd) in a tomato crop on a property in the Muchea area, north of Perth.

Department Quarantine Pathologist Alison Mackie said industry had been advised and growers were being asked to check their crops for signs of PSTVd.

"The symptoms can include stiffening of plants, nodes at intersections of leaves or branches and purple and yellow discolouration of leaves.

"PSTVd is highly transferable. It can spread from one infected plant through the transmission of plant sap by direct handling of plants, the use of cutting or pruning tools, contaminated machinery, animals, clothes or footwear."

The virus has previously been found three times in Australia (once in WA in 2001) and was successfully eradicated each time. The national plant health committee has been notified about the detection.

Ms Mackie said there was little risk of it spreading due to the isolation of the property where it was discovered and the nature of the disease.

There is no vector for PSTVd such as an insect that can distribute it further and the disease can be controlled by good crop hygiene.

Ms Mackie advised growers that symptoms of PSTVd could be confused with nutrient imbalance, spray damage, insect damage or other plant diseases such as viruses.

Potato spindle tuber viroid affects the nightshade group of solanaceous plants. It is a serious disease of potatoes, capsicums and tomatoes.

"Severe strains in potatoes can result in a loss of tuber yield of up to 65 per cent. In tomatoes, yield loss can be up to 50 per cent."

Initial introduction into potato crops is mostly through infected tubers. Viroid introduction into tomato crops may occur from infected seed.

A fact sheet on the viroid including specific symptoms in different crops and large colour images is available at www.affa.gov.au: search reference Potato Spindle. Suspect samples should be sent to the Department of Agriculture's Plant Laboratory at 3 Baron Hay Court, South Perth for testing. The laboratory can be contacted on 9368 3721.
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