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Background and Aims: A region's suitability for viticulture is commonly categorised by thermal‐based bioclimatic indices during the growing season, of which the growing season temperature (GST) is the most widely used. Growing season temperature thresholds, however, were developed for a specific region and therefore may not translate to other established wine regions, including Australia. This paper aims to investigate and refine the application of GST in modelling spatial suitability of existing wine regions in south‐east Australia. Methods and Results: Locations suitable for winegrapes according to traditional GST were mapped and compared with established wine regions. Inconsistencies were identified, and a range of refinements was applied in order to improve the spatial representation. Conclusions: This study highlights the benefit of three improvements to the GST parameter in order to successfully represent Australian wine regions. First, a latitude adjustment was applied to the GST to account for varying day length. Second, significant temporal variability in GST over the last 15–20 years was identified, highlighting the challenge of selecting a period that represents 'average conditions' for such studies. Third, in order to model the spatial extent of Australian wine regions, the inclusion of a 'hot' GST classification (19–22°C) was needed. Significance of the Study: These refinements allow for the successful quantification of climatic conditions for Australian viticulture. Refined GST thresholds can be applied to future climate projections, providing the industry with vital information and guidance on how to react and adapt to the challenges of climate change. [ABSTRACT FROM AUTHOR]

Background and Aims International quarantine rules prohibit exports of fruit from areas with fruit flies. Cold storage was tested from 1989 to 2012 as a postharvest treatment against the Mediterranean fruit fly (Medfly) in nine cultivars of Australian grown tablegrapes. The paper shows how market access was obtained. It reviews the methods, models and science that underpin fruit fly disinfestation. Methods and Results Tablegrapes were infested with immature stages of Medfly for large scale tests seeking 99.99% mortality at the upper 95% confidence level. Infested berries were exposed to 1, 2 and 3°C for 12, 13, 14, 15, 16, 18 and 20 days. No survivors were found in fruit held at 1°C for 16 days, 2°C for 18 days and 3°C for 20 days. Conclusion The data presented satisfy international requirements for access to quarantine-restricted markets. Several decades of research are reviewed to show how science and phytosanitary regulation can be used to harmonise cold disinfestation treatments. Significance of Study This work has enabled Australia's tablegrape industry to gain access to several international markets. The science used and presented is expected to benefit disinfestation research. [ABSTRACT FROM AUTHOR]

While winegrowers usually want to achieve consistent yield targets, there is a high degree of yield and price (and hence gross revenue) variability in winegrape production. The aim of this study was to determine whether there are differences in yield and revenue variability across climates, varieties, and regions in Australia. This was performed by estimating statistical models of the impact of these three variables on the coefficient of variation of yield and gross revenue per hectare. The results suggest that hotter and drier regions exhibit lower interannual yield variability, something that in the past may have been largely explained by the use of irrigation, but which may change in the future with climate change and higher water prices. The results also showed that there are sometimes differences in yield and revenue variability, not only across regions, but also between varieties. [ABSTRACT FROM AUTHOR]

Background and Aims. Grape phylloxera in Australia comprises diverse genetic strains that feed on roots and leaves of Vitis spp. The G38 phylloxera strain was detected on roots of Vitis spp., for the first time in North East Victoria in 2015. Prior to 2015, G38 phylloxera was only known to feed on leaves. The aim of this study was to evaluate the survival and development of G38 phylloxera on roots of diverse Vitis spp. under field, controlled laboratory, and greenhouse conditions. Methods and Results. In the field, emergence traps quantified first instars and alates emerging from roots of diverse rootstocks and Vitis vinifera L. High numbers of phylloxera were collected in traps placed at vines of rootstocks 101-14, 3309 Courderc and Schwarzmann. Nodosity were also observed on roots of 101-14, 3309 Courderc and Schwarzmann in the field and in-pot vines experiments. The better performance of G38 phylloxera on these three rootstocks compared to V. vinifera in the field and in potted vines parallelled the excised roots experiments. Conclusions. The relatively high performance of G38 phylloxera on the 101-14, 3309 Courderc and Schwarzmann rootstocks suggest a susceptible response and could be associated with rootstock parentage. Further investigation is warranted to determine implications for rootstocks development. Significance of the Study. These findings are fundamental for decision-making in phylloxera risk assessment and rootstock selection. The study reaffirms the need for triphasic (in vitro, in planta, and in-field) rootstock screening protocols for phylloxera. [ABSTRACT FROM AUTHOR]

Background and Aims. This research investigates spatial and temporal trends in budburst timing across Australian wine regions from 1910–2019. The potential drivers of these observed trends were then identified, including anthropogenic climate change and large-scale climate drivers (El Nino–Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Southern Annular Mode (SAM)). Methods and Results. The timing of budburst was approximated using accumulation measurements applied to Australia wide gridded temperature data. We show that the modelled budburst date has been gradually shifting to earlier in the year for most (95%) Australian wine regions, at an average rate of one day every 24 years. This linear trend in budburst timing is likely to be associated with steadily increasing air temperatures due to anthropogenic climate change. Significant interannual variability was also observed and was correlated with IOD and SAM; however, no significant relationship was found with ENSO. Positive IOD phases result in budburst occurring on average four days earlier than the long-term average; however, this can be as high as eight days. Conclusions. The results of this study highlight that budburst timing for wine grapes is not a stationary phenomenon and is influenced by both natural and anthropogenic conditions. Significance of the Study. Understanding variability and trends in modelled budburst timing will assist tactical and strategic management practices and improve phenological modelling and adaptation planning for climate change. [ABSTRACT FROM AUTHOR]

Background and Aims: Cross‐sectional models are useful for estimating the impact that climate and climate change have on grape prices due to changes in grape composition. The aim of this study is to estimate the impact of growing season temperature (GST) on grape prices in Australia using cross‐sectional data. Methods and Results: We use data on average price by cultivar and region for a 10 year period. We estimate a model using (area‐) weighted least squares and variables from a principal component analysis to control for 103 characteristics that relate to the production system used in each of 26 regions. Results suggest that a GST increase of 1°C leads to a decrease of 9% in the average price of grapes. A LASSO model that we use as a robustness check suggests similar results: a GST increase of 1°C leads to a decrease of 7.3% in the average price of grapes. Conclusions: Failing to control for characteristics that relate to the production system overestimates the impact of GST on grape prices, suggesting that changes to variables in a production system may mitigate deleterious changes to grape composition due to climate change. Significance of the Study: This study contributes to the understanding of the issue of omitted variable bias in cross‐sectional models, and how to deal with this issue when analysing the impact of climate and climate change in grape and wine research. [ABSTRACT FROM AUTHOR]

Background and Aims: An elevated concentration of several volatile phenols and their glycosides in grapes and wines is associated with exposure of grapes to forest fire smoke. Interpretation of phenol compositional data from grapes or wines, however, is complicated by the fact that traces of these compounds can be detected in non‐smoke‐exposed samples. Hence, the concentration of smoke marker compounds was investigated with the aim of providing a reference data set to help determine smoke exposure. Methods and Results: Thirteen phenolic compounds were measured in non‐smoke‐exposed grape berries and unoaked wines made from 12 cultivars collected from multiple regions across Australia over four vintages. The grapes and wines contained a low concentration of several volatile phenols and their glycosides. These varied in concentration between cultivars but showed little variation between regions and vintages. The maximum concentration observed for any analyte was below 15 μg/kg in grapes and approximately 15 μg/L in wine. Conclusions: The results for smoke marker compounds should be considered on a per‐cultivar basis when determining smoke exposure. Interpretation of results for a potentially smoke‐exposed sample can be achieved based on comparison with the 99th percentile values reported here. Use of the interpretation system described should be limited to determining smoke exposure and not smoke taint. Significance of the Study: This study provides a comprehensive set of data that defines the upper limits of smoke marker compounds expected in Australian grapes and wines from non‐smoke‐exposed vineyards that can be used for determining the likelihood of smoke exposure. [ABSTRACT FROM AUTHOR]

Background and Aims: Predicted impacts of climate change—increased temperature, decreased rainfall, and reduced water availability—are expected to increase irrigation‐related salinity in Australia's major wine regions. Breeding of new abiotic stress‐tolerant rootstocks will help to mitigate these effects on viticulture. Here, we investigated the impact of elevated temperature on key salt tolerance traits of two contrasting rootstocks and a population of experimental rootstock hybrids. Methods and Results: A high‐throughput facility was used to phenotype the rootstocks, K51‐40, 140 Ruggeri and 68 K51‐40 derived hybrids, all ungrafted, under factorial salinity and temperature treatments. Elevated temperature led to increased chloride concentration in the mature laminae of most genotypes, likely driven by increased transpiration, with large differences between genotypes in the extent of the temperature response. Genetic differences were also observed for the influence of temperature on laminae sodium accumulation. Growth rate response to salinity was variable between genotypes and was independent of laminae chloride and sodium accumulation. Conclusions: High‐throughput phenomics provides a promising tool to simultaneously assess new rootstock selections for ion exclusion and growth rate response under abiotic stresses. Significance of the Study: Understanding the effect of temperature on salinity tolerance traits, and the development of novel screening tools, will help breed new rootstocks better suited to a hotter and drier future climate. [ABSTRACT FROM AUTHOR]

Background and Aims: Grapegrowers often trial alternative practices to meet business goals. Our aim was to investigate why and how experiments are conducted during grape production, the perceived value of current approaches and opportunities for change. Methods and Results: Semi‐structured interviews were conducted with 35 growers and eight consultants with diverse demographic and business attributes across Australia. Growers and consultants conduct experiments, often over several seasons, to learn about alternative viticultural practices, to gain knowledge, to enhance confidence in changing practice and to solve problems. Trial approaches are diverse and not associated with business or personal attributes. Growers value conclusive results for confident decision‐making; however, they are constrained by available time, labour and lack of efficient, objective measures of crop responses. Spatial variability in land is viewed as a contributor to non‐uniform fruit yield and composition and recognised as a factor confounding trial results. Conclusions: Growers value their experimentation despite facing challenges during the process. They also expressed a desire for robust results which could be addressed by efficient approaches to experimentation that incorporate spatial information and generate results for more informed decision‐making. Significance of the Study: The empirical evidence of growers' experimental behaviours highlights the importance of experimentation to wine businesses and identifies the need for new approaches that generate more useful information to support growers' decisions. [ABSTRACT FROM AUTHOR]

Background and Aims: Declining autumn and winter rainfall increasingly limits soil moisture availability at the onset of the growing season in southern Australia. We studied the consequences of reduced rainfall during dormancy on vine growth, and explored irrigation strategies to maintain yield following dry winters. Methods and Results: The effect of the timing and method of irrigation during dormancy on vine performance was investigated for three seasons in a Shiraz vineyard where late autumn and winter rainfall was excluded using shelters. Reduced soil moisture in spring delayed the time of budburst. A reduction in rain to approximately one third of the historical average reduced yield (24–42%) and canopy size (16–31%). Natural rain (Control) or equivalent sprinkler irrigation, providing water during winter, resulted in a higher yield: pruning mass ratio, but reduction in yield was still observed when drip irrigation was used to replace winter rain. Refilling the soil profile in spring after dry winters favoured growth partitioning towards canopy and roots, increased carbohydrate reserves in the trunk, but reduced yield (−10 to −32%). Conclusions: Irrigation during winter did not fully offset the decline in production. Refilling the soil profile at the end of winter increased vigour, and reduced yield. Reduced soil moisture prior to spring delayed the time of budburst. Significance of the Study: Vineyard management aiming to sustain yield under a changing climate will need to incorporate winter irrigation. Models predicting the time of budburst under a changing environment could be fine‐tuned by incorporating soil moisture availability. [ABSTRACT FROM AUTHOR]

Background and Aims: Grapevine phenology is closely linked with growing season temperature. Rising temperature related to anthropogenic climate change has the potential to advance winegrape ripening. This study updated and validated previous research that considered changes to the timing of winegrape maturity and to the warming temperature of the growing season as well as added several new vineyard data sets. Length of the harvest period was assessed to determine if time between harvests of different cultivars has shortened. Methods and Results: Vineyard records from 31 vineyard blocks in 13 Australian wine regions, in conjunction with gridded temperature data, were used to assess changes to maturity timing and mean growing season temperature. Trends towards earlier maturity were evident as were increases to mean growing season temperature for all vineyard blocks and regions considered. Trends varied in magnitude as well as by cultivar and region. Compression of the harvest period occurred for half of the regions studied. Conclusions: Winegrape maturity in Australia has continued to advance in line with warming temperature, which has implications for grape composition and wine quality. Compression of the harvest period was found in some cases, though varied by region and cultivars grown. Significance of the Study: This study validated the trend towards earlier winegrape maturity with continued warming temperature and extended a valuable phenological data set. In light of record warming, earlier maturity is becoming the new norm. The method used to investigate compression of the harvest period in this study is applicable to other winegrowing regions worldwide. [ABSTRACT FROM AUTHOR]

Background and Aims Grape phylloxera, Daktulosphaira vitifoliae Fitch, causes damage to ungrafted European grapevines, Vitis vinifera L. Where distribution is limited such as in Australia and China, phylloxera is managed primarily through quarantine protocols. In Australia, there are 83 known phylloxera genetic strains, and studies have shown differences in susceptibility to some disinfestation treatments. First instar nymphs are the most dispersive stage and can be transferred from infested to healthy vineyards on footwear and hand held tools. The current disinfestation protocol recommends a footbath treatment for 30 s with 2% sodium hypochlorite (NaOCl) followed by a water rinse. Methods and Results Survival of six endemic phylloxera genetic strains, G1, G4, G7, G19, G20 and G30, was determined by immersing first instars in 0, 2, 3 and 4% NaOCl for 30, 40 and 60 s followed by a 30 s water rinse. Although phylloxera survival was significantly reduced by increasing NaOCl concentration and treatment duration, none of the treatment combinations were 100% effective. By excluding the post-treatment water rinse, 100% mortality was achieved across all the six genetic strains using a treatment of 2% NaOCl for 60 s. Conclusions Results from this study recommend a revised disinfestation treatment for footwear and hand held tools. Significance of the Study It is important to consider differences in susceptibility to disinfestation treatments by phylloxera genetic strains. [ABSTRACT FROM AUTHOR]