12 September 2017
Extensive investigation by the Department of Primary Industries and Regional Development (DPIRD) into the movement of potatoes throughout Western Australia has discovered that infected dormant dahlia tubers grown on a potato growing property are the likely source of Dickeya dianthicola infection in Western Australia.
Following sampling from 27 properties and traces to some 64 properties, the department discovered that the dahlia tubers had been planted first, with potatoes subsequently planted in the same plot.
Dickeya dianthicola has a large potential host range, including not only potatoes but a range of ornamental flowers, as well as artichoke and chicory. It can persist in the soil for up to 12 months, and now appears to be easily transferred between different host crops.
Tracing has also found that these infected dahlia tubers originated from other states. Other states are now undertaking surveillance and testing for Dickeya dianthicola, both in potato and dahlia crops.
The department is continuing to assist growers by developing management options. This includes assessing how the Certified Potato Seed Scheme can be modified to manage Dickeya dianthicola.
DPIRD has also asked industry to consider and endorse a proposed strategy for the disease including the lifting of quarantine restrictions. Growers would then be responsible for managing the disease to minimise future impacts on the industry.
If quarantine is lifted, potatoes from infected properties may be sold as seed, with buyers being responsible for managing the risk involved.
Currently DPIRD has identified four infected premises, six dangerous contact premises, four suspect premises and 54 trace properties.
International market access for WA potatoes remains unaffected.
The Consultative Committee on Emergency Plant Pests has agreed that tomatoes are not a host of Dickeya dianthicola.
Working with quarantined properties
While quarantine restrictions remain, DPIRD proposes that potatoes from quarantined properties may only be sold as ware under biosecurity protocols.
To facilitate this, either a Quarantine Notice or a Pest Exclusion Notice has been issued to the four growers to transport potatoes to a potato wash/packer.
DPIRD staff have visited five potato wash/packing facilities to assess their biosecurity measures, and Pest Exclusion Notices have been issued to these facilities.
DPIRD is no longer collecting samples from non-quarantined properties. Any future sampling will be limited to infected premises. Additional requests for testing can be undertaken on a fee-for-service basis.
As of 4 September 2017, DPIRD has received 3416 samples of which 625 are ornamentals and 2765 are potatoes. 135 individual samples have been detected with the disease.
Laboratory test result reports are being provided to growers as they become available.
Funding under the Emergency Plant Pest Response Deed (EPPRD)
This Deed is a legally binding agreement between Plant Health Australia, all Australian governments and national industry bodies on how to report and respond to emergency plant pests. It outlines the roles and responsibilities of industry and government in decision making and funding of responses to emergency plants pests.
The EPPRD is the plant sector equivalent of the Emergency Animal Disease Response Agreement.
The EPPRD is triggered as soon as a suspect emergency plant pest is reported to Australia’s Chief Plant Protection Officer.
Under the EPPRD, Owner Reimbursement Costs (ORCs) may be available to growers, but only when a response plan under the EPPRD is agreed nationally and all other relevant provisions of the EPPRD are met.
In the case of Dickeya dianthicola there is no nationally agreed response plan.
ORCs cover the agreed costs of crops or property that have been damaged or destroyed in the course of activities completed in accordance with an agreed response plan. Although, the ORC is limited in what it can reimburse and does not cover consequential losses.
Testing process for Dickeya dianthicola
Waiting times for test results have to date averaged 7-10 days, and sometimes longer if re-testing is required.
Testing of samples is a complicated and lengthy procedure, involving sample preparation, incubation, DNA extraction, followed by a primary polymerase chain reaction (PCR) test. If Dickeya is suspected then a further PCR test is required to confirm Dickeya dianthicola.
If Dickeya is not detected in samples via the primary test, then waiting times are reduced as the second test is not required.
Waiting times will increase if samples are received on a Friday, due to the overnight incubation step.
Three grower meetings were held last month in Manjimup, Bunbury and Gingin. The meetings were hosted by DPIRD.
As a follow-up from the meetings, DPIRD is looking into a number of issues raised:
- Modification of the Certification Potato Seed Scheme and Registration Rules to manage the disease.
- Assess the capacity of the department’s diagnostic laboratory service to carry out fee-for-service testing.
- Risk management and on-farm biosecurity measures.
- Identifying disease resistant potato varieties.
- Sources for the purchase of clean seed.
- Chemicals available for disease control.
New biosecurity information sheets available
The following information sheets are now available from the DPIRD website:
- Biosecurity checklist for growers
- Biosecurity checklist for potato wash/packers
- Decontamination guidelines
- Destruction and disposal guidelines
- Dickeya dianthicola in potatoes
- Dickeya dianthicola in dahlias
Industry contacts for growers
Potato Growers Association of WA
Phone: (08) 9481 0834