Grapevine trunk disease experts are recommending cutting as low as possible when remediating vines, rather than only 10-20 cm below the visible staining.
“It has become evident that infections can arise from watershoots lower down the trunk, and Botryosphaeria pathogens seem to be present much further in front of the internal staining in trunks, than was previously reported from experiments using one year old canes,” said Dr Mark Sosnowski.
Mark, who is Sub-Program Leader of Horticulture Pathology at the Department of Primary Industries and Regions research division South Australian Research and Development Institute (SARDI), is leading a national Wine Australia project with research teams at SARDI and the Gulbali Institute (Charles Sturt University) exploring new approaches for grapevine trunk disease (GTD) management.
GTDs are a major pressure in Australian vineyards, reducing yield and causing vine decline and death. Spores infect exposed pruning wounds, with vines being most susceptible to infection in the first two weeks after pruning.
Mark works collaboratively with other researchers in Australia and around the world, to develop strategies for minimising the impact of GTDs, such as applying wound treatments to pruning cuts to prevent infection, and remedial surgery (lopping affected vines at the trunk) to eradicate the pathogen.
To reduce trunk disease infection rates, experts recommend:
- Prioritise younger, healthy vines for pruning in dry conditions and apply preventative sprays.
- Remediate infected vines by cutting out all signs of infection from cordons and trunks and cutting as low as possible. Follow up by painting wounds with paint or a registered wound sealant.
- Where possible, avoid pruning during rainfall when airborne spores of GTD pathogens are most prevalent.
- Consider mechanical pre-pruning in early to mid-winter and clean up by hand later in the winter when the risk of infection is reduced.
- Protect annual pruning wounds by spraying with a registered fungicide within 1 week of pruning, ensuring good coverage. Fungicides will provide up to 2 weeks’ further protection, which should be sufficient to cover the duration of wound susceptibility. Registered fungicides are Sprayseal (tebuconazole) and Emblem or Gem (fluazinam) and can be applied with vineyard sprayers. There are also registered paste products such as Greenseal and Garrison which need to be hand applied and are mainly used for large wounds when reworking.
- Contamination of pruning tools is not a major risk of spreading GTD within the vineyard, but always clean pruning tools when moving between blocks and vineyards.
For more information, read the Grapevine Trunk Diseases Best Practice Management Guide which can be downloaded from the Wine Australia website.
