Overview
The report provides an analysis of grapevine recovery from fire damage after the December 2019 Adelaide Hills bushfire, including a return on investment analysis. Three seasons of trials compared trunk renewal immediately after the fire or in winter, and spur pruning, cane pruning or trunk replacement. Spur pruning gave the highest three-year yield on mildly damaged vines and the best economic return for both mildly and moderately damaged vines. Trunk replacement gave the poorest return unless damage was severe or trunk disease was present. Modelled recovery costs ranged from about $4,300 per hectare for minor repairs to $45,900 for a full replant. The report recommends restoring irrigation first, leaving regrowth to rebuild reserves, and assessing damage before committing to costly treatments.
The Cudlee Creek bushfire started on Friday, 20 December 2019. Around 1,100ha of vineyard in the northern part of the Adelaide Hills wine region were burnt. For grape and wine businesses affected by the fire or smoke, the impacts were significant. The fires not only destroyed sheds, machinery and equipment, they also directly damaged vineyards, trellis and irrigation infrastructure.
Vineyard owners and managers with moderate to severe damage were faced with three choices to manage their grapevines: begin revival immediately, wait until dormancy to review vine recovery from fire damage before commencing remedial action, or remove damaged vines and re-establish new plantings.
However, the fact that these events have been rare in the past means that there has been very little opportunity to study the recovery of vines after fire and to determine the best course of action to return a vineyard to productivity.
A multi-year demonstration trial was established in the Adelaide Hills by Colin Hinze (Pinion Advisory) and Richard Hamilton (Hamilton Viticulture) to take advantage of the opportunity. The aim was to provide data to determine the optimal time to begin vine recovery (immediately after the fire or once dormant) and the best method for winter pruning (spur, cane or trunk renewal) for recovering vineyards.
The project showed that accelerated economic recovery and return to full production is best achieved by taking time to fully understand the damage to vines, so that high-cost solutions are not implemented when unnecessary. The following actions are recommended:
- Restore the irrigation system as soon as possible to optimise vine recovery and maximise carbohydrate reserves for dormancy
- Thoroughly assess the impact of fire on the vineyard (mild, moderate or severe) to inform subsequent action. Vineyard variability combined with uneven fire impact can mean that the level of damage will vary between individual vines within a vineyard. Guidelines were developed to assist with the classification
- Wait while the vines recover. Don’t remove any regrowth - let the vines maximise carbohydrate storage as they enter dormancy. In the meantime, continue operational management to maximise vine health, and take the opportunity to critically assess the vineyard viability, profitability and other production issues (e.g. block performance, varietal desirability, trunk disease incidence). Consider layering to replace any missing vines.
- For mildly and moderately damaged vineyards, continuing with spur pruning in the winter following the fire is a reasonable economic option and likely to be the most effective strategy over the medium term. Conversion to cane pruning or trunk replacement is only necessary where there are other advantages, such as the influence on grape quality (e.g. bunch architecture) or remediation of trunk disease.
Abstract
In the summer of 2019-20, Australia was devastated by a significant bushfire season that affected large areas of the country. The Cudlee Creek bushfire in the Adelaide Hills in December 2019 directly damaged around 1,100ha of grapevines as well as causing concerns with smoke damage to grapes.
The Department of Primary Industries and Regions, South Australia (PIRSA) and Wine Grape Council of SA released funding obtained under the Local Economic Recovery program for a project to establish and monitor bushfire recovery trials in Adelaide Hills vineyards over two vintages – 2021 and 2022. Wine Australia partnered with PIRSA to provide funding for a third season of trials (2023) and to generate extension materials for the grape and wine sector on the results of the project.
Trial work was established over several sites in the Adelaide Hills. Results provide evidence-based advice for growers on management of vines which have been directly damaged by fire and the best ways to return a vineyard to productivity.
Objectives
The primary objective of this project is to extend bushfire recovery trials in the Adelaide Hills for a third season, to allow three small-scale trial sites to continue to be managed and monitored across vintage 2023. The trials are designed to:>
- evaluate different pruning options for returning vines to production after they have been damaged by fire
- evaluate the timing of trunk removal and renewal (immediately post-fire compared to winter pruning) for returning vines to production
- determine a realistic range of costs associated with commercial scale recovery activities following damage by fire
Background
The Cudlee Creek bushfire in the Adelaide Hills in December 2019 directly impacted on vineyards in the region. As well as concerns with smoke damage to grapes, fires damaged grapevines directly across large areas. The fact that these events have been rare in the past means that there has been very little opportunity to study the recovery of vines after fire. In response,
The Department of Primary Industries and Regions, South Australia (PIRSA) and Wine Grape Council of SA funded a project with Pinion Advisory and Hamilton Viticulture to establish and monitor bushfire recovery trials in Adelaide Hills vineyards over two vintages – 2021 and 2022. Wine Australia partnered with PIRSA to provide funding for a third season of trials (2023) and to generate extension materials for the grape and wine sector.
Approach
The project will manage and monitor three bushfire recovery trial sites in the Adelaide Hills for a third season. Activities include:
- Recording of key phenology stages and manage vines at trial sites
- Recording of yield components for all treatments
- Collation of data for the final season
- Capture of photography and video content from trial sites.
Results from the first two seasons were reported on posters at AWITC18 in June 2022. Additional extension materials and digital content will be generated by the end of the project, to inform grapegrowers and winemakers the best methods and timing for vine recovery after damage by fire. In addition, a seminar (or webinar) of findings will be presented to industry as well as a feature article of findings for industry publication. All resources will be housed on the Wine Australia website.
Sector benefits
All Australian vineyard managers face the increasing risk of damage by fire, due to changes in both climatic conditions and management practices. Findings from this project will be invaluable for vineyard managers if (when) they face the scenario of recovery from fire damage in the future.
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