Cool wine regions to benefit from research on new pathogen

The pathogen, which favours cool and moist conditions, is thought to be most problematic in cool wine regions where many growers use overhead sprinkler systems to prevent frost damage, unintentionally creating conditions in which Pss thrives.
NSW DPI research scientist Dr Melanie Weckert said the new research aims to develop a better understanding of Pss and will hopefully lead to effective management strategies.
'We have confirmed that Pss was responsible for bacterial inflorescence rot (BIR) which damaged young bunches in the Tumbarumba vineyards during the last two seasons,' Weckert said.
'Now, we're able to focus on control measures with a trial of six different treatments in the form of soil drenches and trunk injections, currently under way in Tumbarumba.'
The NWGIC and Grape and Wine Research and Development Corporation decided to fund a doctoral study into the effect of Pss on grapevines after evidence of Pss was detected in sap from the damaged vines.
'We found that Pss overwinters in the trunk and buds, which explains why copper fungicide sprays have been ineffective in stopping the spread of BIR in Tumbarumba,' Weckert said.
'Once it has spread to the trunk we are unable to prune the infected section.'
The NSW DPI is working directly with growers in the Tumbarumba district and running vine health field days with the NWGIC to keep growers up-to-date with research progress.
Though Pseudomonas syringae affects many horticultural crops, it has not previously been seen as a serious threat to winegrapes. Mild symptoms of Pss in winegrapes were first recorded in South Australian vineyards during spring 2000.
The pathogen has rarely occurred in grapevines overseas, with cases recorded in Argentina, Sardinia and Azerbaijan in the late 1970s and 1980s.

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