One of Vinehealth Australia’s primary functions under our Phylloxera and Grape Industry Act 1995 is to identify and assess the relative threat to the state’s vineyards posed by phylloxera and other diseases or conditions that may affect vines.
Accordingly, Vinehealth Australia has started to undertake field sampling to collect more than 200 diagnostic samples for analysis for Grapevine Red Blotch virus (GRBV) and a range of endemic viruses, from key properties of interest.
This follows the surveillance Vinehealth undertook for GRBV in late winter/early spring last year after the announcement of GRBV having been detected in a Western Australian germplasm.
Mid to late autumn has been identified by virologists as a key time for sampling for GRBV when virus titre is thought to be at its highest, and therefore most readily detectable in grapevine tissue.
Vinehealth Australia and South Australian Vine Improvement Association (SAVIA) are working hand-in-hand to demonstrate industry leadership in this response, to collectively ensure that South Australia gains considerable confidence in the GRBV status of its propagation material.
A number of South Australia’s Vine Improvement Associations are undertaking considerable levels of GRBV testing, and in part this is being supported by financial contributions from Wine Australia.
From this, we can contribute valuable insights nationally into what is the biggest coordinated response to a new pest/disease or pathogen in viticulture in Australia.
GRBV sampling is being undertaken preferentially on South Australian properties with links to other properties on which GRBV positive grapevines have been verified in Australia.
South Australia’s autumn surveillance is expected to contribute the following knowledge:
- Incidence of GRBV in South Australia in the plantings tested, including identification of affected grapevine varieties and clones.
- Indication or otherwise of visual vine symptoms.
- Indication or otherwise of within-property virus spread.
- Association of GRBV with other endemic viruses.
- Level of confidence in GRBV diagnostics.
This knowledge will provide an informed starting point for additional trace-forward, including to commercial properties, and a strong basis from which informed management decisions can be implemented.
While Vinehealth Australia is not calling for South Australian vineyard owners to send in grapevine samples for GRBV analysis at this point, we ask you to keep a look out for visual leaf symptoms, which are known to be variable, and can be confused with leafroll virus.
If you have a block with a relatively large number of vines showing virus symptoms, also reflect on the berry sugar accumulation rate of the block this vintage in comparison to other blocks. If this is up to 5˚ Brix lower than comparative blocks and leafroll-type leaf symptoms are widely evident in the block, please consider calling Vinehealth Australia on 08 8273 0550 to discuss.
We refer you to the AWRI’s GRBV fact sheet for further information on symptoms and testing – noting that GRBV is not a standard test at most laboratories and must be requested. Diagnostic laboratories are still required to report positive results to their respective state jurisdiction.