Ask the AWRI articles are published in the Australian & New Zealand Grapegrower & Winemaker and are reproduced with permission from the publisher, Winetitles.
2024
Time, temperature and urea – the ethyl carbamate connection (PDF)
Cordingley, B. 2024. Ask the AWRI: Time, temperature and urea – the ethyl carbamate connection Australian & New Zealand Grapegrower & Winemaker (731): 44-45.
Abstract: Ethyl carbamate is a naturally occurring colourless and odourless chemical found in wine. It has been identified as a possible human carcinogen based on animal studies (JECFA 2006). In this article, AWRI Oenologist Ben Cordingley addresses winemaker questions relating to its occurrence and formation, as well as practices that result in lower ethyl carbamate concentrations.
The impact of 2,4-D herbicides on grapevines (PDF)
Schlank, R. 2024. Ask the AWRI: The impact of 2,4-D herbicides on grapevines Australian & New Zealand Grapegrower & Winemaker (729): 42-46.
Abstract: In addressing several Helpdesk inquiries concerning spray drift in vineyards throughout Australia, AWRI Viticulturist, Dr Rochelle Schlank, explores some of the key questions surrounding the impact of 2,4-D on grapevines, particularly those relating to yield and vegetative responses.
Calcium oxalate deposits – kidney stones in wine? (PDF)
Coulter, A. 2024. Ask the AWRI: Calcium oxalate deposits – kidney stones in wine? Australian & New Zealand Grapegrower & Winemaker (725): 70-71.
Abstract: While calcium tartrate instability in wine is well known and was discussed in a previous ‘Ask the AWRI’ column (Holdstock 2016), winemakers may be less familiar with a more peculiar calcium instability: calcium oxalate. In humans, calcium oxalate crystals are the most common type of kidney stone. However, in wine, these crystals only seem to occur in Botrytis wines. In this column, AWRI Senior Oenologist, Adrian Coulter, responds to questions about this enigmatic, crystalline deposit.
Crown gall in Australian Vineyards. (PDF)
Dixon, R. 2024. Ask the AWRI: Crown gall in Australian vineyards Australian & New Zealand Grapegrower & Winemaker (723): 74-76.
Abstract: The AWRI helpdesk has received reports of crown gall-like symptoms affecting young vines in a number of regions in Australia. A response to this issue is currently being coordinated by an industry response group, with representatives from industry bodies, State Government Departments and diagnostic laboratories. In this article, AWRI Senior Viticulturist Robyn Dixon briefly summarises current knowledge of crown gall disease, acknowledging that scientific understanding of this issue is changing quickly.
Salt damage in vineyards. (PDF)
Essling, M. 2024. Ask the AWRI: Salt damage in vineyards Australian & New Zealand Grapegrower & Winemaker (720): 35-37.
Abstract: Salinity and salt damage to grapevines is something growers might commonly expect to encounter after several years of drought conditions. Despite three years of generally wetter conditions, and sometimes flooded areas, growers have recently contacted the AWRI helpdesk about suspected salt damage in their vineyards. In a climate that is forecast to be drier, it is important to understand the impact that salinity can have, make sure growers are monitoring for it, and have strategies to prevent salt build-up. In this column, AWRI Senior Viticulturist Marcel Essling addresses some of the symptoms of salt issues in vineyards and outlines practices for managing salinity.
2023
Does having thick skin pay off when it comes to measuring sugar in grapes? (PDF)
Cowey, G. 2023. Ask the AWRI: Does having thick skin pay off when it comes to measuring sugar in grapes? Australian & New Zealand Grapegrower & Winemaker (718): 48-49.
Abstract: Winemakers recently asked the AWRI helpdesk why some grape varieties produce wines with greater than expected alcohol concentrations, even when based on initial glucose plus fructose (G+F) concentrations measured in pressed grape juice. Is it because varieties with small berries and/or thick skins have additional sugar extracted from their skins during skin maceration, or during skin contact in red wine fermentations? In this article, AWRI Senior Oenologist Geoff Cowey investigates whether initial sugar concentration measured in pressed juice from thick versus thin-skinned varieties differs from the sugar concentration measured in an equivalent homogenate sample.
Gases – we have you covered. (PDF)
Cordingley, B. 2023. Ask the AWRI: Gases – we have you covered. Australian & New Zealand Grapegrower & Winemaker (716): 68-69.
Abstract: Carbon dioxide (CO₂) was in short supply to several sectors during early 2023 and was selling at around double the usual price. This cost increase and concerns about sustainability led some winemakers to ask the AWRI helpdesk for advice on how to use CO₂ or other gases most efficiently when protecting wine during storage. In this column, AWRI Oenologist Ben Cordingley covers questions about using different gases and which delivery methods provide the most efficient and effective protection.
Measuring the environmental footprint of Australian grapes and wine. (PDF)
Longbottom, M. 2023. Ask the AWRI: Measuring the environmental footprint of Australian grapes and wine. Australian & New Zealand Grapegrower & Winemaker (715): 74-75.
Abstract: There is currently significant interest from grapegrowers and winemakers in understanding the environmental footprint of grapes and wine and taking steps to reduce environmental impacts, in particular greenhouse gas emissions. In this column, AWRI Manager – Sustainability and Viticulture, Dr Mardi Longbottom, explores the technique of life cycle assessment and some opportunities for reducing emissions in viticulture.
Understanding copper hazes in wine. (PDF)
Coulter, A. 2023. Ask the AWRI: Understanding copper hazes in wine. Australian & New Zealand Grapegrower & Winemaker (714): 78-79.
Abstract: When hazes or deposits form in white wine, there are a range of possible culprits, including protein, polysaccharides or even microorganisms. Of these, copper casse is an instability that occasionally displays unusual properties, with the associated haze sometimes observable and at other times not. In this column, AWRI Senior Oenologist, Adrian Coulter, responds to some of the questions commonly asked about copper casse and explains its sometimes curious behaviour.
Varietal and clonal identification of grapevines. (PDF)
Borneman, A. 2023. Ask the AWRI: Varietal and clonal identification of grapevines. Australian & New Zealand Grapegrower & Winemaker (713): 38-39.
Abstract: The AWRI helpdesk is contacted from time to time by producers asking about options for testing either the variety or the clone of grapevine material. In this column, AWRI Research Manager, Dr Anthony Borneman, answers questions about the latest scientific advances in this area.
Traditional cap management techniques. (PDF)
Cowey, G. 2023. Ask the AWRI: Traditional cap management techniques. Australian & New Zealand Grapegrower & Winemaker (712): 58-59.
Abstract: Plunging, pump-overs and ‘rack and returns’ are traditional cap management options performed during a red wine fermentation. How these techniques are performed can vary significantly between wineries and one or all of them may be used throughout a single ferment. There are limited operational instructions within textbooks because cap management is used to achieve different objectives at different times during fermentation. In this column, AWRI Senior Oenologist, Geoff Cowey answers questions about when and how these practices are typically used.
Assessing grapes for disease. (PDF)
Dixon, R. 2023. Ask the AWRI: Assessing grapes for disease. Australian & New Zealand Grapegrower & Winemaker (711): 90-91.
Abstract: In seasons where conditions favour the development of fungal diseases, grapegrowers and winemakers are under pressure to meet quality targets by managing the level of disease-affected fruit entering the winery. This can be difficult for both parties. In this article, AWRI Senior Viticulturist Robyn Dixon explores some of the tools and resources available to grapegrowers and winemakers to manage disease assessments in a fair, equitable and mutually beneficial manner.
Understanding Australian sustainability credentials. (PDF)
Longbottom, M. 2023. Ask the AWRI: Understanding Australian sustainability credentials. Australian & New Zealand Grapegrower & Winemaker (710): 45-46.
Abstract: Sustainability is an area of increasing focus in the Australian wine industry, driven by consumer and market demand and the inherent desire of our producers to protect their land and livelihoods for future generations. In this column, Dr Mardi Longbottom answers some of the key questions about sustainability credentials and metrics that allow Australian producers to demonstrate their performance on a global stage.
Coulter, A. 2023. Ask the AWRI: Wine taints from oak. Australian & New Zealand Grapegrower & Winemaker (709): 56-57.
Abstract: The AWRI helpdesk has conducted numerous investigations over the past 40 years of taints in wines caused by the use of tainted additives and processing aids. A previous ‘Ask the AWRI’ column answered some general taint-related questions and outlined a sensory screening method for assessing additives and processing aids for the presence of taints (Holdstock 2017). In this column, AWRI Senior Oenologist, Adrian Coulter, responds to questions about taints originating from oak barrels and other oak products.
Cordingley, B. 2023. Ask the AWRI: Thinking about pinking. Australian & New Zealand Grapegrower & Winemaker (708): 46-47.
Abstract: The AWRI helpdesk has recently observed an increase in cases of pink colour development in 2022 vintage white wines soon after bottling, particularly in white wines made using ‘reductive’ winemaking practices. Affected producers have asked AWRI Oenologist Ben Cordingley questions about why this is occurring, how to best determine pinking susceptibility in these types of wines and the most appropriate prevention and/or treatment options.
2022
Winery nutrient management in a DAP-limited world. (PDF)
Cowey, G., Schmidt, S. Ask the AWRI: Winery nutrient management in a DAP-limited world. Australian & New Zealand Grapegrower & Winemaker (707): 46-47; 2022.
Abstract: Food and agricultural sectors across the globe are currently experiencing reduced availability and/or increased cost of nitrogen-based fertilisers and additives, including urea and diammonium phosphate (DAP). The previous ‘Ask the AWRI’ column addressed the implications of urea limitations in the vineyard. In this column, AWRI Senior Oenologist, Geoff Cowey, and Research Manager – Biosciences, Dr Simon Schmidt, consider options for optimising nitrogen in the winery if DAP availability remains limited.
Vineyard nitrogen management in a urea-limited world. (PDF)
Dixon, R., Cowey, G. Ask the AWRI: Vineyard nitrogen management in a urea-limited world. Australian & New Zealand Grapegrower & Winemaker (706): 54-55; 2022.
Abstract: Many food and agricultural sectors are currently dealing with reduced availability and/or increased cost of nitrogen-based fertilisers and additives. Australia imports 90% of its nitrogen-based chemicals from India, Morocco and China. Reduced worldwide production of these chemicals due to natural gas being redirected for energy needs has resulted in major export nations such as China and Russia placing restrictions on exports of urea to control prices in their own domestic markets. This has increased prices on the international market by a factor of three to four since December 2019 (e.g. the price of urea has increased from ~AU$300 to more than $1,200/metric tonne) (Index Mundi, May 2022). In this article, AWRI Senior Viticulturist Robyn Dixon and Senior Oenologist Geoff Cowey address some of the options for managing vineyard nitrogen levels in a urea-limited world.
Schwarz, C. Ask the AWRI: How’s the weather? Australian & New Zealand Grapegrower & Winemaker (705): 66-67; 2022.
Abstract: There are many different sources where grapegrowers can access weather data, and how it is presented and interpreted can vary. In this article, Christa Schwarz, Technical Officer – Viticulture, reviews some of the most useful websites, apps and portals that are available.
Stinky sulfur compounds in wine. (PDF)
Coulter, A. Ask the AWRI: Stinky sulfur compounds in wine. Australian & New Zealand Grapegrower & Winemaker (704): 85-86; 2022.
Abstract: The AWRI frequently receives queries about off-characters in wine caused by reduced sulfur compounds. In this column AWRI Senior Oenologist, Adrian Coulter, responds to typical questions asked about such characters.
Factors involved in ‘mothballing’ vineyards. (PDF)
Essling, M. Ask the AWRI: Factors involved in ‘mothballing’ vineyards. Australian & New Zealand Grapegrower & Winemaker (703): 69-70; 2022.
Abstract: From time to time vineyard owners may have reasons to ‘mothball’ a block for a period of time. This involves minimising management costs, while protecting vines to ensure they can be rapidly brought back to productive use when needed. The AWRI helpdesk is sometimes approached for advice by vineyard owners considering this option. This column by Senior Viticulturist, Marcel Essling, provides information on the factors to be taken account when thinking about mothballing a vineyard.
Techniques to detect Brettanomyces before it’s too late. (PDF)
Cordingley, B. Ask the AWRI: Techniques to detect Brettanomyces before it’s too late. Australian & New Zealand Grapegrower & Winemaker (702): 70-71; 2022.
Abstract: The early detection of Brettanomyces bruxellensis yeast or ‘Brett’ can allow winemakers to take action before the concentration of volatile phenols becomes detrimental to wine quality. In this article, AWRI Oenologist Ben Cordingley answers questions on different technologies for the detection of Brett cells in wine.
Importing new grape varieties. (PDF)
Longbottom, M. Ask the AWRI: Importing new grape varieties. Australian & New Zealand Grapegrower & Winemaker (701): 78, 80; 2022.
Abstract: In response to changes in the climate and market demand, growers and winemakers in Australia may be looking to adjust the mix of grape varieties they produce. In this column, AWRI Manager Sustainability and Viticulture, Dr Mardi Longbottom answers some key questions about importing new varieties.
Effects of COVID-19 on sense of smell. (PDF)
Cowey, G. Ask the AWRI: Effects of COVID-19 on sense of smell. Australian & New Zealand Grapegrower & Winemaker (700): 48-50; 2022.
Abstract: Winemakers who have contracted COVID-19 have asked the AWRI helpdesk about one of the common symptoms: loss of or distorted sense of smell. Senior Oenologist, Geoff Cowey, has waded through the published clinical research on this topic to answer the most common questions and provide a curated list of references with more detailed information.
How to get the most out of copper sprays. (PDF)
Essling, M., Schwarz, C. Ask the AWRI: How to get the most out of copper sprays. Australian & New Zealand Grapegrower & Winemaker (699): 76-78; 2022.
Abstract: After well over a century of use in viticulture to control diseases, copper sprays are still an important tool for protection against downy mildew. They do, however, need to be used judiciously to avoid accumulation of copper in soil to levels that have a negative effect on soil health. In this column, AWRI Senior Viticulturist, Marcel Essling and Technical Officer – Viticulture, Christa Schwarz address some common questions received by the AWRI helpdesk about copper use in the vineyard.
Interpreting AWRI smoke panel analysis results. (PDF)
Coulter, A. Ask the AWRI: Interpreting AWRI smoke panel analysis results. Australian & New Zealand Grapegrower & Winemaker (698): 42-43; 2022.
Abstract: AWRI Commercial Services has recently changed the way smoke panel analysis results are reported. Apart from the numerical results, reports now include graphs showing where the results sit compared to levels typically present in non-smoke-exposed grapes or wines. In this column, Senior Oenologist Adrian Coulter explains various aspects of the graphical results and how they should be interpreted.
How to tame an unruly canopy. (PDF)
Dixon, R. Ask the AWRI: How to tame an unruly canopy. Australian & New Zealand Grapegrower & Winemaker (697): 54-57; 2022.
Abstract: After a wet season across much of Australia, particularly on the east coast, some growers have now found themselves with large, unruly canopies and more wet weather on the way, prompting questions about the best way to manage vigorous canopies. In this column AWRI Senior Viticulturist Robyn Dixon outlines a variety of canopy management options.
Sacrificial yeast cultures for SO2 reduction. (PDF)
Cordingley, B. Ask the AWRI: Sacrificial yeast cultures for SO2 reduction. Australian & New Zealand Grapegrower & Winemaker (696): 52-53; 2022.
Abstract: Occasionally winemakers find themselves in situations where there are small amounts of sulfur dioxide (SO₂) in white grape juice that could impede primary fermentation or inhibit a coinoculated malolactic fermentation, yet the concentration is not high enough to consider removal with hydrogen peroxide. This can occur due to over-additions of SO₂ during harvest, transport, crushing and/or pressing. In this column AWRI Oenologist Ben Cordingley investigates the use of yeast additions to remove small amounts of free SO₂ from juice before the main inoculation is conducted, commonly known as a sacrificial yeast culture.
2021
Schmidt, S., Holdstock, M. Ask the AWRI: Aerating red ferments. Australian & New Zealand Grapegrower & Winemaker (695): 53-54; 2021.
Abstract: The influence of oxygen on wine fermentation has been studied at the AWRI since 2014. Over that time, a great deal has been learned
about how to use oxygen to achieve different winemaking goals. In this column, AWRI Research Manager, Dr Simon Schmidt and AWRI Senior Oenologist, Matt Holdstock explore answers to key questions winemakers might ask before trialling oxygen addition next vintage, with a focus on red fermentations.
Longbottom, M. Ask the AWRI: Carbon accounting. Australian & New Zealand Grapegrower & Winemaker (694): 44-45; 2021.
Abstract: With growing global interest in sustainability, Australain grapegrowers are showing an increasing interest in options for measuring and demonstrating their impacts on the environment. In this column, AWRI Manager – Sustainability and Viticulture, Dr Mardi Longbottom, answers some of the more common questions about carbon accounting in viticulture.
How much wine to expect per tonne of grapes. (PDF)
Cowey, G. Ask the AWRI: How much wine to expect per tonne of grapes. Australian & New Zealand Grapegrower & Winemaker (693): 52-53; 2021.
Abstract: A winery’s production size is often described in the wine trade by the number of bottles or cases produced, while winemakers tend to talk about the number of tonnes crushed and a viticulturist might define production by yield from their vineyard. But how do these numbers correlate? In this article, Senior Oenologist Geoff Cowey explores how many cases of wine might be expected from a metric tonne of grapes processed by different size wineries, considering a range of possible variables.
Best practice weed management and the future of herbicides. (PDF)
Essling, M. Ask the AWRI: Best practice weed management and the future of herbicides. Australian & New Zealand Grapegrower & Winemaker (692): 20; 2021.
Abstract: Weeds in vineyards are those non-beneficial plants that can have an adverse impact on crop yield, grape quality and vineyard operations. They can also harbour vineyard pests and disease. Weeds are managed in a variety of ways, including with the spraying of herbicides. In this column, AWRI Senior Viticulturist Marcel Essling answers questions about the future of using herbicides to control weeds.
Titratable acidity increase during fermentation. (PDF)
Coulter, A. Ask the AWRI: Titratable acidity increase during fermentation. Australian & New Zealand Grapegrower & Winemaker (691): 68, 70; 2021.
Abstract: A previous Ask the AWRI column (Issue 608) described various aspects of acidity and briefly discussed the phenomenon of titratable acidity (TA) increase during fermentation. In this column, Adrian Coulter responds to more specific questions received by the AWRI helpdesk about TA increases due to acid production by yeast, without any evidence of spoilage.
Effects of fermentation temperature on red wine composition. (PDF)
Godden, P. Ask the AWRI: Effects of fermentation temperature on red wine composition. Australian & New Zealand Grapegrower & Winemaker (690): 50-52; 2021.
Abstract: During tastings of the AWRI’s winemaking treatment trial wines held with winemakers around Australia, the red wines produced with increased fermentation temperature were almost universally the most preferred. This paper examines how a relatively small winemaking change can result in a large difference in wine composition and sensory properties.
Torulaspora delbrueckii – An ancient yeast creating new wines. (PDF)
Cordingley, B. Ask the AWRI: Torulaspora delbrueckii – An ancient yeast creating new wines. Australian & New Zealand Grapegrower & Winemaker (689): 64-65; 2021.
Abstract: Torulaspora delbrueckii is an indigenous non-Saccharomyces wine yeast often found in uninoculated ferments, both today and as far back as Roman times. Despite its long history, pure commercial strains of this yeast have only been available for little over a decade. In this article, AWRI Oenologist Ben Cordingley addresses some of the reasons winemakers are choosing to innoculate ferments with T. delbrueckii.
Organic and sustainable production. (PDF)
Pitcher, L. Ask the AWRI: Organic and sustainable production. Australian & New Zealand Grapegrower & Winemaker (688): 94-95; 2021.
Abstract: The adoption of organic and sustainable grape and wine production practices is increasing around the world in response to a range of factors. Organic and sustainable production systems have many similarities, with both aiming to protect and enhance the natural environment and ecological diversity. The two systems do, however, have different approaches to achieving those aims. In this column, Liz Pitcher, AWRI Sustainability and Viticulture Specialist, addresses some of the more common questions about these two production systems.
How much sulfur dioxide (SO2) is needed at bottling? (PDF)
Cowey, G., Coulter, A. Ask the AWRI: How much sulfur dioxide (SO2) is needed at bottling? Australian & New Zealand Grapegrower & Winemaker (687): 76-77; 2021.
Abstract: The AWRI helpdesk is often asked how much SO2 is required in bottled wine, both to inhibit microbiological growth and prevent oxidation or premature wine development. Some winemakers also ask if less or more SO2 is required for different wine types, wine intended to be sealed with different types of closures or wines that will be aged for different amounts of time. In this column Geoff Cowey and Adrian Coulter address these questions.
Use of elicitors in viticulture (PDF)
Essling, M. Ask the AWRI: Use of elicitors in viticulture. Australian & New Zealand Grapegrower & Winemaker (686) : p. 35; 2021.
Abstract: The AWRI helpdesk is often asked about new products being marketed to grapegrowers. One such type of product is elicitors, which are promoted as having a range of benefits. In this column, Marcel Essling provided answers to some common questions about elicitors.
Applying regenerative agriculture practices in viticulture (PDF)
Dixon, R. Applying regenerative agriculture practices in viticulture. Australian & New Zealand Grapegrower & Winemaker (685) : 40-41; 2021.
Abstract: Proponents of regenerative agriculture often point to the importance of improving soil health as a way of safeguarding food production systems from climate change. Some even suggest that improving soil health will slow the progession of climate change through carbon bio-sequestration. In this column, AWRI Senior Viticulturist Robyn Dixon explores the benefits of improving soil health and how regenerative agriculture can be adapted to viticulture.
Microwaving wine – a scientific perspective (PDF)
Coulter, A. Microwaving wine – a scientific perspective. Australian & New Zealand Grapegrower & Winemaker (684) : 44-45; 2021.
Abstract: In this column, AWRI Senior Oenologist Adrian Coulter approaches the question “Is it OK to bring a glass of wine to room temperature in a microwave oven?” from a scientific point of perspective.
2020
Lees contact in white wine (PDF)
Godden, P. Lees contact in white wine. Australian & New Zealand Grapegrower & Winemaker (683) : 55-56; 2020.
Abstract: In this column, Peter Godden continues a series examining the effects of winemaking variables on Chardonnay composition and style – this time focusing on post-fermentation lees contact in white winemaking.
Sparkling wine gushing: not a cause for celebration (PDF)
Cordingley, B. Sparkling wine gushing: not a cause for celebration. Australian & New Zealand Grapegrower & Winemaker (682) : 42-43; 2020.
Abstract: Many consumers have had the experience of opening a bottle of sparkling wine and having the contents spontaneously gush from the bottle. In this column, AWRI Oenologist Ben Cordingley addresses questions asked by sparkling winemakers about why unintentional gushing occurs, the main causes, and what steps can be taken to prevent its occurrence.
Indole off-flavour in sparkling wine (PDF)
Cowey, G. Indole off-flavour in sparkling wine. Australian & New Zealand Grapegrower & Winemaker (681) : 46-47; 2020.
Abstract: In recent years, the AWRI helpdesk has received queries from a number of companies about indole off-flavours developing during the secondary fermentation of some tank-fermented sparkling wines. In this column, the author draws on general information and data obtained from a 2019 trial to answer some questions about indole.
The importance of soil organic matter (PDF)
Essling, M. The importance of soil organic matter. Australian & New Zealand Grapegrower & Winemaker (680) : 82-83; 2020.
Abstract: This article answers the following questions: What is soil organic matter and is it different from soil organic carbon? What is soil organic carbon? Should I be trying to increase my soil carbon? What is the right amount of soil organic carbon for my vineyard? What are some of the options to increase soil organic carbon?
DMDC – an insurance policy (PDF)
Coulter, A. DMDC – an insurance policy Australian & New Zealand Grapegrower & Winemaker (679) : 52-53; 2020.
Abstract: Dimethyl dicarbonate (DMDC) is a chemical antimicrobial additive that can be used in addition to sulfur dioxide when there is increased risk of microbiological growth in wine. Its main use has been as an insurance policy when bottling wines with residual sugar or as a control against Brettanomyces or other viable microorganisms when adequate levels of sulfur dioxide or filtration are not achievable. In this column, Adrian Coulter answers some of the questions that arise when winemakers consider using DMDC at bottling.
Cowey, G. Amber wine Australian & New Zealand Grapegrower & Winemaker (678) : 49-50; 2020.
Abstract: Since 2016, the AWRI has made a series of wines from single batches of grapes, changing one variable in each fermentation, with the resulting wines being presented to winemakers in workshops around Australia. In this column, Geoff Cowey explores key questions from winemakers on full skin contact in
white winemaking – that is, the production of amber wines – one of the treatments included in the 2019 Chardonnay trial.
Understanding the factors that influence grapevine yield (PDF)
Longbottom, M. Understanding the factors that influence grapevine yield Australian & New Zealand Grapegrower & Winemaker (677) : 34-35; 2020.
Abstract: Many Australian grapegrowing regions experienced lower than average yields in the past season and are now reflecting on the possible causes. Information gathered from across a number of regions suggests that, for many, low yield was caused by both fewer and smaller bunches. Both bunch number and berry number per bunch can be affected by external environmental influences (light exposure, temperature, humidity and wind) and the internal physiology of the grapevine (water, nutrient and hormone status). It is important to understand the different timings of these influences and the contributions of the
different components of yield in order to manage and avoid low yields in the future. In this column Dr Mardi Longbottom explores key questions on the factors that influence yield.
Pre-fermentation skin contact (PDF)
Godden, P. Pre-fermentation skin contact Australian & New Zealand Grapegrower & Winemaker (676) : 52-53; 2020.
Abstract: Since 2016 the AWRI has made a series of wines from single batches of grapes, changing one variable in each fermentation, with the resulting wines being presented to winemakers in workshops around Australia. In this column, the AWRI’s Peter Godden covers key questions on pre-fermentation skin contact in white winemaking – one of the treatments included in the 2019 trial.
Promoting grapevine recovery after fire damage (PDF)
Longbottom, M. Promoting grapevine recovery after fire damage Australian & New Zealand Grapegrower & Winemaker (675) : 66-67; 2020.
Abstract: Recent bushfires in regions including the Adelaide Hills, Kangaroo Island and Tumbarumba have seen grapevines in some vineyards damaged by fire. In this column, Dr Mardi Longbottom answers questions about how best to deal with a fire-damaged vineyard.
Discrepancies in analytical results for volatile acidity (PDF)
Coulter, A. Discrepancies in analytical results for volatile acidity Australian & New Zealand Grapegrower & Winemaker (674) : p.64; 2020.
Abstract: The AWRI has recently received queries about differences between results of volatile acidity (VA) analyses conducted overseas and those conducted in Australia. This column answers some of the questions raised when this issue arises.
Essling, M. Spray application Australian & New Zealand Grapegrower & Winemaker (673) : 36-37; 2020.
Abstract: For the past four years, the AWRI has been coordinating workshops on vineyard spray application in regions across Australia, with the most recent workshops held in Western Australia in November 2019. This column summarises the most common questions about spray application asked by participants.
Hoare, T. Reworking vineyards Australian & New Zealand Grapegrower & Winemaker (672) : 49-50; 2020.
Abstract: Vineyards established in Australia during the 1990s are now reaching the age where owners are considering whether reworking is required. Decisions may be driven by a decline in yield due to poor vine health and/or a breakdown in vineyard infrastructure such as posts and irrigation systems coming to the end of their life expectancy. AWRI senior viticulturist Tony Hoare covers some of the key questions asked by vineyard owners about reworking vineyards.
2019
Grape solids in white winemaking (PDF)
Godden, P. Grape solids in white winemaking Australian & New Zealand Grapegrower & Winemaker (671) : 73-74; 2019.
Abstract: Since 2016 the Australian Wine Research Institute (AWRI) has made a series of wines from single batches of grapes, changing one variable in each fermentation, with the resulting wines being presented to winemakers in workshops around Australia. In 2019, the trial was conducted with Chardonnay. The AWRI’s Peter Godden covers key questions on grape solids in white winemaking and is the first in a series that will examine winemaking variables included in the 2019 trial that have a significant influence on Chardonnay wine style.
Longbottom, M. Sustainable Winegrowing Australia: supporting the nation’s growers and winemakers in demonstrating and improving their sustainability Australian & New Zealand Grapegrower & Winemaker (670) : 45-46; 2019.
Abstract: The Australian wine industry’s unified sustainability program, Sustainable Winegrowing Australia, was launched in July 2019. In this column Mardi Longbottom addresses some of the most common questions about the program.
What does the latest research say about barrel sanitation against Brett? (PDF)
Cowey, G. What does the latest research say about barrel sanitation against Brett? Australian & New Zealand Grapegrower & Winemaker (669) : 76-77; 2019.
Abstract: When acetic acid bacteria or Brettanomyces yeast grow in a wine during barrel maturation, the AWRI helpdesk is often asked if the barrel can be adequately sanitised and reused without the risk of cross contamination or reinfection. Geoff Cowey covers some of the specific factors that should be considered, including outcomes from recent research on this topic.
Regulatory changes to the use of botrytis agrochemical (PDF)
Essling, M. Regulatory changes to the use of botrytis agrochemical Australian & New Zealand Grapegrower & Winemaker (668) : 48-49; 2019.
Abstract: A recent AWRI eBulletin cautioned wine exporters about shipments to the European Union after a change in the residue tolerance for the agrochemical iprodione – the active constituent in some agrochemicals used to control botrytis. It was recommended that wines be residue tested prior to shipment. The AWRI’s Marcel Essling answers some probing questions into the implications of the regulatory changes for this agrochemical.
Spoilage issues in Pinot Noir (PDF)
Coulter, A. Spoilage issues in Pinot Noir Australian & New Zealand Grapegrower & Winemaker (667) : 68-69; 2019.
Abstract: During the 1990s, a high number of the microbiological instability issues investigated by the AWRI’s helpdesk were associated with bottled Pinot Noir wines (Bruer et al. 1998). Looking at today’s stats, Pinot Noir wines still represent a significant proportion of the microbiological spoilage issues submitted to the helpdesk. In this article Adrian Coulter presents answers to common questions about microbial spoilage in Pinot Noir.
Controlling vineyard weeds (PDF)
Hoare, T. Controlling vineyard weeds Australian & New Zealand Grapegrower & Winemaker (666) : 43-44; 2019.
Abstract: Each year the AWRI helpdesk receives queries about weed control strategies for vineyards and if there are effective alternatives to herbicides. Senior viticulturist at the AWRI Tony Hoare presents some the options available and provides hints for selecting the most suitable weed control for different situations.
Godden, P. Saignée Australian & New Zealand Grapegrower & Winemaker (665) : 91-92; 2019.
Abstract: This article by Peter Godden continues a series examining treatments used in the AWRI’s winemaking treatment trials, which have been presented in tasting workshops across Australia since 2017.
Post-harvest care of tired vines (PDF)
Longbottom, M. Post-harvest care of tired vines Australian & New Zealand Grapegrower & Winemaker (664) : 37-38; 2019.
Abstract: After vintage, the AWRI helpdesk often receives questions about caring for vineyards following the harvest period. Dr Mardi Longbottom outlines answers to some of those questions, particularly regarding water and nutrient demands of stressed vines.
Cleaning winery floors, tanks and hoses (PDF)
Cowey, G. Cleaning winery floors, tanks and hoses Australian & New Zealand Grapegrower & Winemaker (663) : 75-76; 2019.
Abstract: How clean does your winery have to be? Do you need to be able to eat off the floor? Will overly clean wineries prevent ‘winery terroir’, natural fermentations and only produce ‘sterile’ wines? The AWRI helpdesk is often asked about cleaning, sanitising and sterilising operations in the winery. This column, by Geoff Cowey, provides answers to some of the more common questions in this area.
Leafroll viruses – what you need to know (PDF)
Essling, M. Leafroll viruses – what you need to know Australian & New Zealand Grapegrower & Winemaker (662) : 35-36; 2019.
Abstract: The AWRI has been approached by regions with concerns about grapevine leafroll virus type 3 (GLRaV-3). As reports of virus-affected vines become more frequent in Australia, there is a need to better understand the insect vectors involved in their spread and the levels of virus infection at which action needs to be taken. To date, most research has been undertaken in countries which have a longer history of problems caused by viruses, including New Zealand, South Africa and the United States. The findings from this work provide useful guidelines; however, because the growing conditions, virus virulence and insect vectors in those countries may be different, Australian research is also needed.
Will I live longer if I drink alcohol? (PDF)
Stockley, C.S. Will I live longer if I drink alcohol? Australian & New Zealand Grapegrower & Winemaker (661) : 68-69; 2019.
Abstract: The AWRI helpdesk occasionally receives enquiries about the effect of alcohol consumption on longevity. This column provides answers to some questions about the relationship between alcohol consumption and other lifestyle factors on the risk of death from all causes, and some of the more common chronic diseases.
Understanding molecular SO2 calculators (PDF)
Coulter,A. Understanding molecular SO2 calculators Australian & New Zealand Grapegrower & Winemaker (660) : 62-63; 2019.
Abstract: A previous Ask the AWRI column (January 2017) described the importance of molecular SO2and how to calculate it. This column responds to recent questions received by the AWRI helpdesk about the different online molecular SO2 calculators available and why they can give different results.
2018
Reducing vineyard energy use (PDF)
Longbottom, M. Reducing vineyard energy use. Australian & New Zealand Grapegrower & Winemaker (659) : 44-45; 2018.
Abstract: Fuel and electricity use are both major costs and sources of greenhouse gas (GHG) emissions in vineyards. Pumping irrigation and tractor use are the two largest sources of energy use in vineyards. If energy use is high, it is important to consider whether alternative practices with potential to reduce energy demand can be implemented. This column provides answers to questions about ways to reduce water demand or the need to run tractors; however, it is recommended that growers carry out vineyard trials to evaluate changed practices at the local scale.
Extended post-fermentation maceration (PDF)
Godden, P. Extended post-fermentation maceration. Australian & New Zealand Grapegrower & Winemaker (658) : 70-71; 2018.
Abstract: This article continues a series examining treatments used in the AWRI’s winemaking treatment trials, which have been the subject of tastings staged around Australia since 2016.
Winemaking with high pH, high TA and high potassium fruit (PDF)
Cowey, G. Winemaking with high pH, high TA and high potassium fruit. Australian & New Zealand Grapegrower & Winemaker (657) : 80-81; 2018.
Abstract: Some winemakers across Australia noted unusual behaviour in acidity when making acid adjustments to red musts during the 2018 vintage. Acid additions often resulted in a rise instead of a decrease in pH, and a much higher titratable acidity (TA) than expected. This behaviour was caused by high potassium concentrations in fruit. This column summarises the winemaking issues experienced when working with grapes that have elevated potassium levels and high pH.
Using composted grape marc in the vineyard (PDF)
Essling, M. Using composted grape marc in the vineyard. Australian & New Zealand Grapegrower & Winemaker (656) : 48-49; 2018.
Abstract: The AWRI helpdesk recently received a query from a grower who had applied composted grape mare at a rate of 70 cubic metres per hectare to their vineyard, but had some concerns as to whether this application would have an effect on fruit quality. The mare used had been composted for six years. This column explores some of the possible benefits and risks of using composted mare in vineyards.
Alcohol during pregnancy and breastfeeding (PDF)
Stockley, C.S. Alcohol during pregnancy and breastfeeding. Australian & New Zealand Grapegrower & Winemaker (655) : 83-84; 2018.
Abstract: The AWRI helpdesk occasionally receives enquiries about drinking alcoholic beverages, including wine, during pregnancy and breastfeeding. This column provides answers to some key questions about the effects of alcohol on the developing foetus and child.
Coulter, A. Lightstruck character. Australian & New Zealand Grapegrower & Winemaker (654) : 76-77; 2018.
Abstract: The AWRI sometimes receives enquiries regarding development of ‘lightstruck’ character in bottled wine during storage. This column provides a brief summary of this phenomenon.
Brown marmorated stink bug (PDF)
Longbottom, M. Brown marmorated stink bug. Australian & New Zealand Grapegrower & Winemaker (653) : p. 53; 2018.
Abstract: Brown marmorated stink bug (BMSB) is an exotic pest, known to cause damage to a range of crops in other countries. This year dead and alive brown marmorated stink bugs (BMSBs) were detected in Australia in several shipping containers from Italy. The Department of Agriculture and Water Resources implemented off-shore treatment measures between January and April to ensure that the risk of more live BMSBs arriving in Australia was minimised. While this pest is currently not established in Australia, it is one of Australia’s top 40 high priority plant pests. This column provides answers to common questions about this bug, and why it should be taken seriously as a threat to Australian viticulture.
Understanding whole-bunch fermentation (PDF)
Godden, P. Understanding whole-bunch fermentation. Australian & New Zealand Grapegrower & Winemaker (652) : p. 63; 2018.
Abstract: During the 2016 and 2017 vintages, the AWRI made small-lot Pinot Noir and Shiraz wines from single batches of fruit, demonstrating the effects of changing one winemaking variable at a time. During tastings of those wines presented across Australia, many winemakers asked why there are such large sensory differences between wines made with 100% pure carbonic maceration and those made with the more common whole-bunch fermentation treatment. A previous ‘Ask the AWRI’ discussed carbonic maceration, and this one examines whole-bunch fermentation.
Cowey, G. Carbonic maceration. Australian & New Zealand Grapegrower & Winemaker (651) : 70-71; 2018.
Abstract: During the 2016 and 2017 vintages, the AWRI made small-lot Pinot Noir and Shiraz wines from single batches of fruit, demonstrating the effects of changing one winemaking variable at a time. During tastings of these wines presented across Australia, many winemakers have asked why there are such large sensory differences between wines made with 100% pure carbonic maceration and those made with the more common semi-carbonic maceration treatment or whole bunch fermentation. This column explores what is happening during carbonic maceration.
Essling, M. Spray drift. Australian & New Zealand Grapegrower & Winemaker (650) : 34-35; 2018.
Abstract: Damage to grapevines caused by herbicides drifting onto vineyards from sprays conducted on nearby properties occurs occasionally in Australia. Queries about this issue, commonly known as ‘spray drift’, are received from time to time by the AWRI helpdesk. This column provides answers to some of the more common questions about this topic.
Wine instabilities – the solids won’t hurt you (PDF)
Stockley, C. Wine instabilities – the solids won’t hurt you. Australian & New Zealand Grapegrower & Winemaker (649) : p. 66; 2018.
Abstract: A range of hazes and deposits can form in wine and these can sometimes cause concerns for consumers. The AWRI helpdesk has recently received queries asking if there are any health risks associated with consuming wines affected by hazes or deposits. This column discusses the common instabilities seen in wine and provides reassurance that they do not pose health or safety risks.
Coulter, A. Volatile Acidity. Australian & New Zealand Grapegrower & Winemaker (648) : p. 16; 2018.
Abstract: Analysis of volatile acidity (VA) was probably the wine industry’s first measure of wine quality and is routinely used as an indicator of wine spoilage. This column looks at some of the questions AWRI helpdesk staff commonly receive about VA.
2017
Biosecurity and viticulture (PDF)
Longbottom, M. Biosecurity and viticulture. Australian & New Zealand Grapegrower & Winemaker (647) : 44-45; 2017.
Abstract: Australia has a fortunate status as an island nation that is free of many pests and diseases found in other countries, but from time to time new issues are discovered. Most of these are not of major concern, but are nevertheless dealt with seriously to protect Australia’s valuable agricultural industries. This column presents answers to some common questions about Australia’s biosecurity management system.
Stockley, C. Wine – a weighty issue. Australian & New Zealand Grapegrower & Winemaker (646) : p. 44; 2017.
Abstract: The AWRI helpdesk often receives enquiries about the calorie content of wine and whether wine makes you ‘fat’. This column provides answers to some key questions about body weight and the consumption of alcoholic beverages.
Godden, P. Sooty mould. Australian & New Zealand Grapegrower & Winemaker (645) : 30-32; 2017.
Abstract: During the 2017 vintage, some wine-grape growers in several regions were severely affected by ‘sooty mould’. The thresholds for the presence of all moulds at which some wine producers downgrade or reject fruit is 3%, which means that there is potential for sooty mould to cause significant economic losses to grapegrowers. In addition, any effects of sooty mould on the composition and sensory qualities of wine are not well understood. This column provides answers to some common questions about sooty mould.
Vineyard snail control: exploring the options and the timing (PDF)
Essling, M. Vineyard snail control: exploring the options and the timing. Australian & New Zealand Grapegrower & Winemaker (643) : 46-47; 2017.
Abstract: Snails are a vineyard pest that can cause damage to buds and foliage, particularly during spring. This article provides answers to questions commonly raised with the AWRI helpdesk about controlling snails in vineyards.
The tricks and traps of deacidification (PDF)
Coulter, A. The tricks and traps of deacidification. Australian & New Zealand Grapegrower & Winemaker (642) : 56-57; 2017.
Abstract: The cooler than usual 2017 vintage resulted in some wines with higher titratable acidity (TA) levels than usual. In some cases, circumstances necessitated deacidification and winemakers contacted the helpdesk requesting advice. This column focuses on the chemical deacidification of wine using permitted carbonate salts.
Soil analysis and soil carbon: what should you be looking for when getting your soil tested? (PDF)
Longbottom, M. Soil analysis and soil carbon: what should you be looking for when getting your soil tested?. Australian & New Zealand Grapegrower & Winemaker (641) : 44-45; 2017.
Abstract: Soil sampling is a useful management tool that can be used prior to establishing a vineyard and also throughout the productive life of grapevines. Soil analysis can provide critical information about the key properties of soil, nutrient status, fertiliser requirements or to monitor the efficacy of soil amelioration, for example the addition of lime or gypsum.
Why was there more powdery mildew than usual this season? (PDF)
Essling, M. Why was there more powdery mildew than usual this season? Australian & New Zealand Grapegrower & Winemaker (640) : 30-31; 2017.
Abstract: Powdery mildew is caused by the fungus Erysiphe necator (formerly Uncinula necator). Unlike most fungi, the powdery mildew fungus relies on wet weather for only a small part of its lifecycle. It usually develops in dry conditions but spreads most extensively at high humidity in mild, cloudy weather, inside shaded canopies. One reason for this is that the fungus grows on the surface of infected foliage and is retarded by direct exposure to sunlight.
Adding water to high sugar must (PDF)
Cowey, G. Adding water to high sugar must. Australian & New Zealand Grapegrower & Winemaker (639) : 88-89; 2017.
Abstract: In February, an amendment was made to the Australia New Zealand Food Standards Code (FSC) to allow limited addition of water to high sugar must and juice to reduce the chance of fermentation problems. Previously water had not been allowed as a direct additive to grape juice, must or wine, with a maximum (cumulative) addition of 70 mL/L water allowable only for the incorporation of permitted additives or processing aids during the winemaking process.
Holdstock, M. Taints in wine. Australian & New Zealand Grapegrower & Winemaker (638) : p. 64; 2017.
Abstract: Each year the AWRI helpdesk investigates a range of taints in wines. In some of these cases, the taints cannot be remediated, and the wine is left unsaleable. It is therefore important to understand the more common sources of taints and take steps to avoid them. Some of the more frequent questions asked about taints are answered below.
Assessing and managing disease levels close to harvest (PDF)
Petrie, P. Assessing and managing disease levels close to harvest. Australian & New Zealand Grapegrower & Winemaker (637) : 32-33; 2017.
Abstract: This article looks at how to manage disease-affected grapes close to harvest.
Understanding molecular SO2 (PDF)
Coulter, A. Understanding molecular SO2. Australian & New Zealand Grapegrower & Winemaker (636) : p. 76; 2017.
Abstract: Sulfur dioxide (SO2) is a key preservative used in winemaking, but how it works in wine is quite complicated. Concentrations of SO2 required to prevent microbial growth are often quoted as molecular SO2, but winemakers can be more familiar with discussing free and total SO2. This column brings together answers to some of the more common questions about the different forms of SO2 in wine, how much is needed and which factors can change its effectiveness.
2016
Grapevine tissue analysis (PDF)
Longbottom, M. Grapevine tissue analysis. Australian & New Zealand Grapegrower & Winemaker (635) : 36-37; 2016.
Abstract: Grapevine tissue analysis can provide critical information about vine nutrient status to assist with fertiliser decisions, problem diagnosis and monitoring the impacts of management practices. This article provides answers to some of the most common questions on this topic.
Wine consumption and brain health (PDF)
Stockley, C.S. Wine consumption and brain health. Australian & New Zealand Grapegrower & Winemaker (634) : p. 82; 2016.
Abstract: Research has recently been conducted on the effects of alcohol (and specifically wine) consumption on brain function, such as cognition and the risk of dementia. This article provides responses to some of the more common questions in this area.
Re-entry periods after vineyard sprays (PDF)
Essling, M. Re-entry periods after vineyard sprays. Australian & New Zealand Grapegrower & Winemaker (633) : p. 54; 2016.
Abstract: The 2016/2017 edition of Agrochemicals registered for use in Australian viticulture (also known as the ‘Dog Book’) for the first time features guidelines about re-entry into vineyards after agrochemicals have been applied. This column summarises some common questions about vineyard re-entry periods.
Calcium and its unpredictable presence (PDF)
Holdstock, M. Calcium and its unpredictable presence. Australian & New Zealand Grapegrower & Winemaker (632) : 68-69; 2016.
Abstract: Earlier in the year this column featured KHT deposits and cold stability. This month the focus is shifting to calcium instabilities, another type of deposit seen quite commonly by the AWRI helpdesk.
Cowey, G. Not so pretty in pink. Australian & New Zealand Grapegrower & Winemaker (631) : p. 86; 2016.
Abstract: Pinking is a term used to describe the sudden and unexpected development of a salmon/bronze colour in white wines after bottling or when poured into a glass. Although the aroma and flavour of the wine generally remain unchanged, the pink colour often can be misconstrued as the brown colour more typically associated with wine oxidation. This appearance can subconsciously influence the consumers’ expectation of the taste of wine, with pink wines often considered oxidised. This article explains pinking and looks at its treatment and prevention.
Help! What cultivar (or clone) is this? (PDF)
Petrie, P. Help! What cultivar (or clone) is this? Australian & New Zealand Grapegrower & Winemaker (630) : 40-41; 2016.
Abstract: While growers and winemakers generally know which grape cultivars they are growing or making into wine, there are a range of scenarios where it is important to be able to definitively identify a rootstock or scion. Accurate cultivar identification is essential for nursery operators as part of their quality assurance programs.
KHT deposits and cold stability (PDF)
Coulter, A. KHT deposits and cold stability. Australian & New Zealand Grapegrower & Winemaker (629) : p. 76; 2016.
Abstract: Potassium bitartrate (KHT) is the crystalline substance that drops out of solution when a wine is cold stabilised. However, if cold stabilisation is unsuccessful, wines can end up with KHT deposits after packaging and these represent around 25–35% of the AWRI helpdesk’s haze/deposit investigations each year. So why does this type of deposit continue to be an issue for the wine industry? The article addresses the following questions:
- So what exactly is ‘cold stability’?
- Which wine parameters affect ‘cold stability’?
- Why does wine pH sometimes change during cold stabilisation?
- What does the saturation temperature value for a wine mean?
- Which ‘cold stability’ test does the AWRI recommend?
Grazing sheep in vineyards (PDF)
Essling, M. Grazing sheep in vineyards. Australian & New Zealand Grapegrower & Winemaker (628) : 46-47; 2016.
Abstract: It is becoming more common to see sheep grazing in Australian vineyards between late autumn and spring. This article addresses the most common questions asked by vineyard owners about this practice.
- What are the benefits of grazing sheep in a vineyard?
- When is the best time to graze sheep in the vineyard and how many should there be?
- What savings can be expected in terms of operating costs and GHG emissions?
- Is infrastructure needed?
- Do agrochemical residues need to be considered?
- Will the sheep cause damage in the vineyard?
- Can any other types of animals be used in vineyards?
Health and nutrition labelling (PDF)
Stockley, C.S. Health and nutrition labelling. Australian & New Zealand Grapegrower & Winemaker (627) : p. 66; 2016.
Abstract: The AWRI helpdesk regularly receives questions about health and nutrition labelling for wine and wine products. Broadly the questions can be divided into the areas of alcohol, allergens, preservatives and health and nutrition statements, which all fall under the auspices of the Australia and New Zealand Food Standards Code. This article addresses some of the most common questions as outlined below.
- How do I express alcohol content?
- Which allergens do I need to label for?
- Do I need to label for preservatives?
- How do I calculate standard drinks?
- Am I permitted to make health and nutrition statements?
- What are the rules for cleanskins?
Predicting alcohol levels (PDF)
Cowey, G. Predicting alcohol levels. Australian & New Zealand Grapegrower & Winemaker (626) : p. 68; 2016.
Abstract: Over the past two vintages winemakers have been reporting higher than normal conversions of sugar to alcohol. One example was a must measured at 13.5 Baume that ended up with a 15% v/v alcohol concentration. Estimating potential alcohols based on grape must analysis is not as straightforward as many winemakers assume. This article addresses some key points to be taken into account.
Petrie, P. Measuring canopy size. Australian & New Zealand Grapegrower & Winemaker (625) : 36-37; 2016.
Abstract: Canopy size and density are important viticultural measures that relate to fruit quality. Traditionally, however, they have been difficult to measure. The University of Adelaide has recently released an app that allows growers to assess grapevine canopies using an iPhone or iPad. Some common questions about using the app are addressed in this article.
Holdstock, M. All things analysis. Australian & New Zealand Grapegrower & Winemaker (624) : 52-53; 2016.
Abstract: Each year the AWRI helpdesk answers a number of enquiries about wine analysis including how to interpret a result or how to troubleshoot a laboratory issue. The questions and answers in this article represent some frequent and some more obscure questions received in the recent past.
2015
Skipping vineyard sprays in dry year (PDF)
Essling, M. Skipping vineyard sprays in dry year. Australian & New Zealand Grapegrower & Winemaker (623) : p. 38; 2015.
Abstract: The articles looks at strategies to control powdery mildew, downy mildew and botrytis during dry years.
Spoilage due to lactic acid bacteria (PDF)
Coulter, A. Spoilage due to lactic acid bacteria. Australian & New Zealand Grapegrower & Winemaker (622) : 76-77; 2015.
Abstract: Lactic acid bacteria (LAB) are the microorganisms that conduct malolactic fermentation (MLF) in winemaking, but they can also cause wine spoilage. Some of the more common questions about LAB spoilage are discussed in this issue.
Nitrous oxide and viticulture (PDF)
Longbottom, M. Nitrous oxide and viticulture. Australian & New Zealand Grapegrower & Winemaker (621) : 42-43; 2015.
Abstract: Nitrous oxide (N2O) is one of the main greenhouse gases (GHGs) contributing to climate change. Over the past three years the AWRI has been working on a project to collect data on N2O emissions from vineyards across Australia and to investigate the effects of different vineyard floor management practices on N2O production.
DIY haze and deposit identification (PDF)
Cowey, G. DIY haze and deposit identification. Australian & New Zealand Grapegrower & Winemaker (620) : p. 87; 2015.
Abstract: A high proportion of questions answered and investigations conducted by the AWRI helpdesk are related to hazes and deposits in wine. While the helpdesk is well equipped to identify both common and unusual hazes and deposits, there are some steps that can be taken in the winery lab or kitchen to achieve a quick DIY identification.
Wine consumption and heart health (PDF)
Stockley, C. Wine consumption and heart health. Australian & New Zealand Grapegrower & Winemaker (619) : p. 72; 2015.
Abstract: A large amount of research has been conducted on the effects of alcohol (and specifically wine) consumption on the risk of cardiovascular disease. This column provides responses to some of the more common questions in this area.
Petrie, P. Bunch stem necrosis. Australian & New Zealand Grapegrower & Winemaker (618) : p. 36; 2015.
Abstract: Last season saw a spike in queries to the AWRI helpdesk about bunch stem necrosis (BSN), with incidence across most Australian regions. While the causes of BSN are not fully understood, this column summarises current knowledge about this disorder.
Holdstock, M. Trouble-free packaging. Australian & New Zealand Grapegrower & Winemaker (617) : p. 92; 2015.
Abstract: The AWRI helpdesk team often receives questions about packaging and avoiding problems when wine goes from tank to bottle and beyond. Some of the more common ones are outlined below. How much SO2 is lost during packaging? I need to add some last minute copper sulfate to my wine, should I push my bottling date back? Do I need to cold stabilise again if I’m sweetening my wine up with grape juice concentrate just before bottling? After my wine was bottled with natural cork closures the bottles were left upright instead of inverted, is this standard practice? My empty glass bottles have been stored outside for a long time, is it still OK to use these? How useful is filterability testing prior to bottling?
Unmanned aerial vehicles (drones) and viticulture (PDF)
Petrie, P. Unmanned aerial vehicles (drones) and viticulture. Australian & New Zealand Grapegrower & Winemaker (616) : p. 47; 2015.
Abstract: Drones can be used to provide information about vineyards such as assessing for frost damage, water stress and missing vines or creating vigour maps.
Coulter, A. Copper: friend or foe? Australian & New Zealand Grapegrower & Winemaker (615) : p. 73; 2015.
Abstract: Copper instabilities are one of the most common metal instabilities, mainly because of the low concentrations required to cause instability. Copper is also a catalyst for oxidation and reduction reactions and again, low concentrations can have an impact. Furthermore, copper reacts with thiols, so it can affect the varietal aromas of wines, especially those where thiols play a major role, such as Sauvignon Blanc and Cabernet Sauvignon.
Rainfall close to harvest (PDF)
Essling, M. Rainfall close to harvest. Australian & New Zealand Grapegrower & Winemaker (614) : p. 32; 2015.
Abstract: Heavy rain in the four-to-six weeks before harvest is always a risk to grape yield and quality. The ripening berry becomes increasingly susceptible to bunch rots as sugar level increases and fruit softens. High humidity and cloudy conditions provide ideal conditions for powdery mildew, but it is the bunch rots that are usually the most difficult to control.
Avoid mousy, off-flavours (PDF)
Cowey, G. Avoid mousy, off-flavours. Australian & New Zealand Grapegrower & Winemaker (613) : p. 50; 2015.
Abstract: Many winemakers are experimenting with new techniques in white winemaking such as high grape solids ferments, extended lees ageing, higher pH with minimal sulfur dioxide (SO2), oxidative ageing and minimal clarification or filtration. In many cases the aim of these practices is to produce white wines with more texture. While these changing practices have resulted in some great successes, they also come with some increased risks. The incidence of both ‘Brett’ and mousy characters in white wines submitted to the AWRI helpdesk is on the rise. Common questions about mousy off-flavour are explored below.
Effects of hot and dry conditions (PDF)
Longbottom, M. Effects of hot and dry conditions. Australian & New Zealand Grapegrower & Winemaker (612) : p. 38; 2015.
Abstract: Hot and dry conditions have been experienced across many Australian wine regions in recent years, resulting in a number of questions to the AWRI helpdesk.
2014
Holdstock, M. The power of pH. Australian & New Zealand Grapegrower & Winemaker (611) : p. 72; 2014.
Abstract: A previous ‘Ask the AWRI’ column looked at acidity and answered the most common questions received about this parameter. This column considers the other equally, if not more, important partner – wine pH. Some winemakers believe this is the single most important analytical parameter to measure when making wine (closely followed by SO2).
Questions about drink driving (PDF)
Stockley, C.S. Questions about drink driving. Australian & New Zealand Grapegrower & Winemaker (610) : p. 66; 2014.
Abstract: Consumers and winemakers often ask questions about how their driving is affected when they drink a glass or two of wine. Why isn’t it safe to drink and drive? Like most countries, Australia has strict laws about drinking alcohol and driving. Across all states and territories, the legal limit for fully licensed drivers has been set at 0.05 blood alcohol concentration (BAC), which equates to 0.05 g of alcohol in a person’s body for every 100 mL of blood. This is the level above which the risk of being involved in a crash increases significantly. When behind the wheel of a vehicle, drivers need total concentration, good coordination, rapid reflexes and the ability to make correct judgements and decisions.
Export focus on residual metals (PDF)
Stockley, C.S. Export focus on residual metals. Australian & New Zealand Grapegrower & Winemaker (609) : p. 80; 2014.
Abstract: In March 2014, Wine Australia issued a warning to wine exporters regarding increased scrutiny of manganese, iron and copper levels in wine by Chinese authorities. Since then, the AWRI helpdesk has received a number of queries from grapegrowers and winemakers concerned about manganese in grapes and wine.
Acidity in all its various aspects (PDF)
Coulter, A.D. Acidity in all its various aspects. Australian & New Zealand Grapegrower & Winemaker (608) : p. 88; 2014.
Abstract: The AWRI often receives queries relating to various aspects of acidity. Given the importance of pH to the stability and development of wine and the importance of titratable acidity (TA) to wine’s sensory properties, this article answers some of the more common acidity-related questions.
Viticulture and greenhouse gas emissions (PDF)
Longbottom, M. Viticulture and greenhouse gas emissions. Australian & New Zealand Grapegrower & Winemaker (607) : p. 54; 2014.
Abstract: Grapegrowers across Australia are already feeling the impact of a changing climate with earlier budburst, shorter winters, compressed vintages and more frequent extreme weather events such as frosts, heat waves and bushfires. Questions and answers about greenhouse gases and climate change as they relate to viticulture are outlined below.
The ABCs of filtration and what works for you (PDF)
Cowey,G. The ABCs of filtration and what works for you. Australian & New Zealand Grapegrower & Winemaker (606) : p. 60; 2014.
Abstract: This article answers some of the more common questions about filtration including: What is the difference between absolute and nominal filter ratings? What is the difference between depth and surface filtration? Can I use cross flow for sterile filtration? What NTU level do I need for filtration? What level of filtration do I need? Does filtration strip out colour and flavour?
Can you achieve yield control in the vineyard without using bunch thinning? (PDF)
Dry, P. Can you achieve yield control in the vineyard without using bunch thinning? Australian & New Zealand Grapegrower & Winemaker (605) : p. 40; 2014.
Abstract: This articles looks at alternative yield control methods like early leaf removal in the bunch zone and the application of an anti- transpirant spray to the whole canopy from the time of flowering.
Here’s the hot topics of vintage 2014 (PDF)
Holdstock, M. Here’s the hot topics of vintage 2014. Australian & New Zealand Grapegrower & Winemaker (604) : p. 79; 2014.
Abstract: The AWRI helpdesk has received more than 420 winemaking-related queries so far during the 2014 vintage. This article presents a snapshot of some of the ‘hot topics’ of 2014. The most frequent query topic to date has been smoke taint. It has been by far the biggest challenge of 2014, representing nearly 25 per cent of all calls received by the AWRI’s helpdesk during the early stages of vintage.
Bunches with ripe and unripe berries (PDF)
Dry, P. Bunches with ripe and unripe berries. Australian & New Zealand Grapegrower & Winemaker (603) : p. 49; 2014.
Abstract: This article presents the observations of the late Dr Bryan Coombe regarding the ‘sweet and sour’ disorder which Dr Coombe documented during 1999/2000 growing season.
Can ‘Brett’ affect white wines? (PDF)
Coulter, A. Can ‘Brett’ affect white wines? Australian & New Zealand Grapegrower & Winemaker (602) : p. 54; 2014.
Abstract: It is well known that Brett spoilage can occur in red wines, however, can Brett spoilage also occur in white wines? The short answer is “yes”. The first case of Brett spoilage in a white wine investigated by the AWRI was in 2000, and there have been occasional cases investigated since then. However, an unusual trend has occurred recently with six cases of Brett in white wine investigated in the past six months. The level of 4-ethylphenol (4-EP), responsible for the Band-aid® aroma associated with Brett growth, ranged from 77 to 1320 ?g/L in these wines.
Canopy damage from herbicides? (PDF)
Essling, M. Canopy damage from herbicides Australian & New Zealand Grapegrower & Winemaker (601) : p. 32; 2014.
Abstract: The AWRI’s viticulture team received a query at the start of flowering from a grower concerned about canopy damage observed in their vineyard. The description of the damage and the photographs provided pointed to herbicides as the likely cause of the problem.
Top tips for a successful yeast culture (PDF)
Cowey, G. Top tips for a successful yeast culture. Australian & New Zealand Grapegrower & Winemaker (600) : p. 42; 2014.
Abstract: This article answers some common questions received at the AWRI about yeast and provides some top tips for yeast rehydration.
2013
If the grape fits then you can grow it (PDF)
Dry, P. If the grape fits then you can grow it. Australian & New Zealand Grapegrower & Winemaker (599) : p. 57; 2013.
Abstract: The AWRI often fields queries about alternative varieties and how they might suit Australian winemaking conditions. In this Ask the AWRI column Peter Dry gives advice on how to source alternative varieties.
Understanding the ABCs of CMCs in stabilisation (PDF)
Coulter, A. Understanding the ABCs of CMCs in stabilisation. Australian & New Zealand Grapegrower & Winemaker (598) : p. 72; 2013.
Abstract: In recent times, the AWRI has received increasing numbers of queries regarding carboxymethylcellulose (CMC) and its use in relation to tartrate stabilisation. Some of the questions received and the responses provided are detailed in this Ask the AWRI column.
Vines: is an oldie necessarily a goodie? (PDF)
Dry, P. Vines: is an oldie necessarily a goodie? Australian & New Zealand Grapegrower & Winemaker (596) : p. 57; 2013.
Abstract: Grape and wine producers often seek to understand the value of ‘old’ vines. In this ‘Ask the AWRI’ column, Peter Dry providers answers to two questions on this topic.
Snapshot of oak-related queries (PDF)
Holdstock, M. Snapshot of oak-related queries. Australian & New Zealand Grapegrower & Winemaker (595) : p. 68; 2013.
Abstract: The AWRI has taken many calls on the subject of oak barrels over the years. Here is a snapshot of some of the more common oak-related questions received.
Vary strategies for successful weed management (PDF)
Essling, M. Vary strategies for successful weed management. Australian & New Zealand Grapegrower & Winemaker (594) : p. 36; 2013.
Abstract: The AWRI often receives queries from grapegrowers regarding the use and efficacy of herbicides. This article addresses some of the more common questions asked.
Wine as part of a healthy diet? Australian Dietary Guidelines 2013 (PDF)
Stockley, M. Wine as part of a healthy diet? Australian Dietary Guidelines 2013. Australian & New Zealand Grapegrower & Winemaker (593) : p. 82-83; 2013.
Abstract: This article summarises findings on wine and health published in the latest iteration of the Australian Dietary Guidelines, launched in February 2013. It includes the summary of a five-year study of older Australians and the impact of low-risk drinking.
Salt in grapes and wine a common issue (PDF)
Longbottom, M. Salt in grapes and wine a common issue. Australian & New Zealand Grapegrower & Winemaker (592) : p. 28-29; 2013.
Abstract: The viticulture team at The Australian Wine Research Institute often field queries from grapegrowers at the AWRI’s roadshows. This article discusses common questions asked about salt in grapes, including measurement techniques and the impact on wine quality.
What’s that smell – is that Brett? Part 2 (PDF)
Cowey, G. What’s that smell – is that Brett? Part 2. Australian & New Zealand Grapegrower & Winemaker (591) : 64-65; 2013.
Abstract: There have been a number of queries lately to the AWRI regarding Brettanomyces, or ‘Brett’, in wine, particularly the perception of Brett in different wine styles and at levels close to the sensory threshold. This article answers some of those questions.
What can you tell me about controlling Botrytis bunch rot without the use of fungicides? (PDF)
Dry, P. What can you tell me about controlling Botrytis bunch rot without the use of fungicides? Australian & New Zealand Grapegrower & Winemaker (589) : p. 28; 2013.
Abstract: In this ‘Ask the AWRI’ column, Peter Dry discusses various techniques for controlling botrytis, including canopy management, early bunch thinning and reducing fruitset.
What’s that smell – is that Brett? (PDF)
Cowey, G. What’s that smell – is that Brett? Australian & New Zealand Grapegrower & Winemaker (588) : 53-54; 2013.
Abstract: With frequent winemaker inquiries about Brett, it is timely to look at this important subject in detail. This is the first in a two-part series on Brettanomyces.
2012
What are the benefits of nutritional analysis and how do I get the most from the results? (PDF)
Longbottom, M. What are the benefits of nutritional analysis and how do I get the most from the results? Australian & New Zealand Grapegrower & Winemaker (587) : p. 49; 2012.
Abstract: This ‘Ask the AWRI’ column discusses how growers can choose the appropriate type of nutrient analysis and maximise the results.
Timing of harvest is a key decision for winemakers. (PDF)
Krstic, M. Timing of harvest is a key decision for winemakers. Australian & New Zealand Grapegrower & Winemaker (585) : 38-39; 2012.
Abstract: In this ‘Ask the AWRI’ column Mark Krstic answers questions on harvest timing and vineyard sampling.
Malolactic fermentation issues explored (PDF)
Coulter, A. Malolactic fermentation issues explored. Australian & New Zealand Grapegrower & Winemaker (584) : p. 86; 2012.
Abstract: Each year the AWRI’s Winemaking and Extension Services team receives numerous queries regarding problems associated with malolactic fermentation (MLF). Some of the more common questions and responses are discussed here.
Strobilurin resistance to powdery mildew in a vineyard (PDF)
Essling, M. Strobilurin resistance to powdery mildew in a vineyard. Australian & New Zealand Grapegrower & Winemaker (583) : p. 46; 2012.
Abstract: The strobilurin group of fungicides has been registered for control of powdery and downy mildews for over a decade. However, the recent occurrence of strobilurin-resistant strains of powdery mildew is a matter of concern and necessitates a change in disease management.
Constant observation key to avoiding dilemma of stuck ferments (PDF)
Holdstock, M. Constant observation key to avoiding dilemma of stuck ferments. Australian & New Zealand Grapegrower & Winemaker (582) : 66-67; 2012.
Abstract: Stuck fermentations are a regular occurrence for one reason or another, and each vintage the winemaking team at The Australian Wine Research Institute field several questions associated with this frustrating problem. Some of the more common questions are answered here by the AWRI team.
Assessing sun-smart protection (PDF)
Essling, M. Assessing sun-smart protection. Australian & New Zealand Grapegrower & Winemaker (581) : 36-37; 2012.
Abstract: This article discusses several ‘sunscreen’ products which reflect ultraviolet and infrared radiation from plant surfaces, and lists application rates to ensure fermentation and sensory properties are not affected.
How and why identify matter other than grapes (PDF)
Cowey, G. How and why identify matter other than grapes. Australian & New Zealand Grapegrower & Winemaker (580) : 77-78; 2012.
Abstract: Harvest is usually the time when The Australian Wine Research Institute (AWRI) is asked a range of questions about different kinds of matter other than grapes (MOG) and its potential implications for wine quality. Here are some of those questions from this harvest.
Mixed cost and quality effects from thinning (PDF)
Longbottom, M. Mixed cost and quality effects from thinning. Australian & New Zealand Grapegrower & Winemaker (579) : p. 52; 2012.
Abstract: The viticulture team at The Australian Wine Research Institute often field queries from grapegrowers at the AWRI’s roadshows. This article discusses using ‘sacrificial’ canes to reduce vine vigour and improve fruit quality and employing bunch thinning techniques to decrease yield and, by way of improved vine balance, achieve better fruit quality.
Rules and regulations on the move (PDF)
Stockley, C. Rules and regulations on the move. Australian & New Zealand Grapegrower & Winemaker (578) : p. 60; 2012.
Abstract: There has been lots of movement with Australian winemaking and labelling legislation, which is causing a great amount of discussion within the Australian wine community. This article presents some of the issues currently being directed to The Australian Wine Research Institute’s (AWRI) health and regulation information manager Creina Stockley.
Root pruning and covercrops combine to control vigour (PDF)
Dry, P. Root pruning and covercrops combine to control vigour. Australian & New Zealand Grapegrower & Winemaker (576) : 29-30; 2012.
Abstract: In its regular viticulture column, the AWRI offers the latest advice on how to keep Chardonnay growth down, and identify the difference between clones, mass-selection and late-season hedging.
2011
The burning questions on smoke taint (PDF)
Coulter, A. Ask the AWRI: The burning questions on smoke taint. Australian & New Zealand Grapegrower & Winemaker (575): 52, 54; 2011.
Abstract: This article discusses smoke damage to grapes and, ultimately, wine.
Ensure top chemical results with the right adjuvants (PDF)
Essling, M. Ask the AWRI: Ensure top chemical results with the right adjuvants. Australian & New Zealand Grapegrower & Winemaker (574): p. 53; 2011.
Abstract: There are various adjuvant products available that allow stomatal flooding, either partial or complete. This article looks at how flooding affects the chemical efficacy of products.
Start preparing now for 2012 (PDF)
Holdstock, M. Ask the AWRI: Start preparing now for 2012 Australian & New Zealand Grapegrower & Winemaker (573): p. 86; 2011.
Abstract: With the 2011 season behind us, it is now time to start thinking about the 2012 vintage. What better way to prepare for the next year than to do a stocktake of the chemicals and additives that will be required in the winery, and to assess whether they are still sound and fit for use. The AWRI winemaking and extension services team are often asked about winemaking chemicals and additives. This article presents some of the most common questions and responses.
Natural balance critical to mealybug control (PDF)
Essling, M., Dry, P. Ask the AWRI: Natural balance critical to mealybug control. Australian & New Zealand Grapegrower & Winemaker (572): 56-57; 2011.
Abstract: In this regular feature called ‘Ask the AWRI’, AWRI staff answer questions posed by readers. The
first question addresses the issue of why mealybugs might be present in winegrape vineyards and
how to manage them. The second question deals with the use of gibberellic acid to loosen up
compact Viognier bunches.
Botrytis – implications in wine development (PDF)
Cowey, G. Ask the AWRI: Botrytis – implications in wine development. Australian & New Zealand Grapegrower & Winemaker (571): 78–78; 2011.
Abstract: Over the past few months, almost one in every five requests for assistance taken by the AWRI’s winemakers has related in some way to the presence of botrytis and laccase. This ‘Ask AWRI’ regular feature answers questions about how affected wines should be treated post-fermentation, ageing and before bottling.
‘Dog Book’ queries collared (PDF)
Essling, E. Ask the AWRI: ‘DogBook’ queries collared. Australian & New Zealand Grapegrower & Winemaker (570): p. 48; 2011.
Abstract: This article explains how many of the recommendations in the AWRI’s publication Agrochemicals
registered for use in Australian viticulture are determined.