Alert issued for new potato pest in WA

The WA Department of Primary Industries and Regional Development is urging potato growers to be alert for signs of disease in crops following the detection of a new bacteria.

The Western Australian Department of Primary Industries and Regional Development (previously the Department of Agriculture and Food, Western Australia) has confirmed the detection of Dickeya dianthicola in a commercial potato crop, and is responding with measures to contain the pest, determine spread and assess the feasibility of eradication.

Dickeya dianthicola is a serious bacterium that can cause tuber soft rot and blackleg in potatoes.

Potato growers are urged to check their crops and report any suspect symptoms. (Please see description below.)

What is Dickeya dianthicola?

Dickeya dianthicola causes soft rot and blackleg in potatoes. It is a serious pest (bacterium) that was not previously known to occur in Australia. Overseas data has indicated significant yield losses in potato crops.

Dickeya dianthicola can also infect other crops such as globe artichoke and chicory, and some species of flowers (eg. Dianthus and Kalanchoe species).

Other pathogens already present in Australia can cause similar soft rot and blackleg symptoms. However, Dickeya dianthicola is more aggressive and causes disease at lower infection levels.

This pest is not associated with the tomato potato psyllid.

Department of Primary Industries and Regional Development response

The pest has been confirmed on one property north of Perth, with a suspect detection from another property in the south-west.

The Department of Primary Industries and Regional Development (DPIRD) has put in place a number of measures to contain the pest including movement controls on host plant material and machinery from the infected and suspect properties, as well as tracing activities.

Two trace properties in the south-west have also been quarantined. The department is working with growers to enable farm business continuity while mitigating the risk of spread.

Support for growers

DPIRD recognises this detection comes at a difficult time for the horticulture industry, in particular potato growers, following the detection of the tomato potato psyllid earlier this year.

DPIRD is working closely with the WA industry and national stakeholders to minimise the impact of this new pest.

The national Consultative Committee on Emergency Plant Pests has met to discuss this detection.  The committee is still considering the possibility for eradication. As the trade in potatoes from WA to other states and territories is currently prohibited, no further trade restrictions have been imposed at this time.

Symptoms

The first symptom of the disease can be poor emergence due to rotting seed tubers. Plants wilt and typically have slimy, wet, black stems extending upwards from the rotting tuber.

Infected tubers are macerated and have a tapioca-like appearance, but may not have the pungent smell associated with typical blackleg.

Dickeya dianthicola can be present in a plant without causing symptoms, particularly if temperatures remain low. Symptoms often develop after a period of hot weather, especially when plants are also stressed.

How does it spread?

It is generally accepted the main source for blackleg infection is latently infected seed tubers.

On-farm biosecurity practices, such as good farm hygiene and early reporting of suspicious symptoms should be in place to prevent the entry, establishment and spread of pests and diseases. Practical advice and information to assist is available through the Farm Biosecurity website farmbiosecurity.com.au

Reporting options

Dickeya dianthicola (Samson et al. 2005) is a prohibited organism for Western Australia. It is important any suspect disease occurrences are reported.

Growers can report any unusual plant symptoms by:

  • Calling the Pest and Disease Information Service on 1800 084 881
  • Sending a photo to DPIRD via the MyPestGuide Reporter app available from the Google Play or Apple store
  • Emailing photos with your name, address and mobile number to info@agric.wa.gov.au

Reproduced from an article by the WA Department of Primary Industries and Regional Development