Blackleg and Black label seed from Tasmania

AuSPICA is the authority that provides certification of seed potatoes throughout Victoria, South Australia and Northern NSW (Guyra).

New symptoms of the disease blackleg were observed in the AuSPICA Scheme for the first time in 2019.

During the 2018/2019 season, AuSPICA collected 160 plant samples that had symptoms of the so-called new blackleg disease. These plant samples were sent for laboratory testing to determine the pathogen(s) involved in the disease.

Laboratory testing showed;

• 104 samples were positive to “new” blackleg,
• 14 samples were positive to “old” blackleg,
• 42 samples were negative and therefore not related to blackleg

Three pathogens were found to be associated with the “new” blackleg.

• Pectobacterium parmentieri (PP)
• Pectobacterium carotovorum brasiliense (PCB)
• Dickeya dianthicola (DD)

Blackleg is an important potato disease for which the primary management is focused on using clean certified seed potatoes. Blackleg can cause significant yield and storage losses, in some cases up to 100% loss. The “new” blackleg is different to the old blackleg in that the disease is more aggressive particularly in the Australian growing conditions.

The recent detection of “new” Blackleg has required AuSPICA to review seed certification tolerances for blackleg, especially for the pathogen Dickeya dianthicola. Due to the significance of this pathogen, and the crop loss reported in overseas experiences, it was decided that there should be a zero tolerance for Dickeya dianthicola in the AuSPICA seed Scheme. This approach also aligns with the blackleg tolerances set in Western Australia.

AuSPICA has a state-of-the-art seed certification database that manages all certification records and provides complete traceability of all certified seed stocks including the associated origin of all seed lots. This data resource has enabled AuSPICA to thoroughly conduct tracebacks of seed lines associated with all detections of blackleg, including Dickeya dianthicola.

Only 4 seed crops were found with Dickeya dianthicola. These seed crops were derived from two lines of seed both with immediate origins in Tasmania. This information has been communicated to Tasmania seed certification authority (TasSeed).

For the benefit of the Australian potato industry, and to protect all seed growers, both in Tasmania and in the AuSPICA seed Scheme, the AuSPICA Board has introduced the requirement that all Black label seed from Tasmania have a “blackleg” tuber laboratory test to show the absence of Dickeya dianthicola. This requirement will be in addition to the existing Potato Cyst Nematode (PCN) testing requirements.

A 400-tuber sample using protocols adapted from overseas will be used to test Black label seed lots from Tasmania. A copy of the laboratory report will need to be forwarded to AuSPICA when crops are submitted for certification.

AuSPICA supports seed potatoes sourced from other seed Schemes, however there must be checks and balances to ensure that risks are managed with appropriate measures. This gives buyers of certified seed confidence that there is a reduced risk of introducing Dickeya dianthicola into new areas by planting clean seed potatoes.

AuSPICA will continue to work to strengthen the seed potato certification Scheme and the associated traceability of certified seed. In doing so, AuSPICA will provide leadership to the Australian potato industry and adopt world best practice to overcome production issues and ensure high quality certified seed potatoes.

 

Contact Dr Nigel Crump nigel.crump@auspica.org.au or Nellie Malseed nellie.malseed@auspica.org.au