Bushfire recovery case studies
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.
Summary
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.