The Australian Wine Research Institute Blog

Technical Review April 2022 issue available online

7 April 2022 >

The April 2022 issue of Technical Review is now available online. Articles and abstracts can be viewed individually, or the full issue can be downloaded. The online format of Technical Review allows you to browse the list of the latest articles on grape and wine production by keyword, view article summaries, read full-text articles from open access journals and order journal articles (not available for open access) from the AWRI Library.

For copyright reasons, access to abstracts is available only to Australian winemakers and grapegrowers who pay the Wine Grapes or Grape Research levies. The technical notes authored by the AWRI are, however, freely available. If you have forgotten your password for the AWRI website, please use the forgotten password link to reset your password.

Below is a snapshot of what’s in this issue:

AWRI Technical Notes
AWRI publications
Current literature – oenology
Current literature – viticulture

eNews – February 2022

25 February 2022 >

Sustainable Winegrowing Australia certification for WIC Winemaking Services

Major grant for no- and low-alcohol production

Smoke background data published

Vintage trials underway

Resources on scale and sooty mould

Latest information on sensors and automation

Sustainable Winegrowing Australia Impact report – coming soon

Order the latest staff publications online

Acknowledgements

Sustainable Winegrowing Australia certification for WIC Winemaking Services

WIC Winemaking Services, the specialist contract winemaking service operated by the AWRI and the University of Adelaide, has just become a certified member of Sustainable Winegrowing Australia. This certification is testament to work conducted by Winemaker, John Gledhill and Assistant Winemaker, Russell Desmond, to collate all the required sustainability data, undergo training to prepare for certification, be audited and then perform any actions resulting from the audit. The team is proud to be able to demonstrate its sustainability credentials to all its clients. For more information on the services available from WIC Winemaking, contact john.gledhill@awri.com.au.

For other wineries or vineyards interested in certification, attendance at a certification training workshop is the first step. To receive notifications of all upcoming AWRI certification workshops, complete this EOI form.

Major grant for no- and low-alcohol production

A $4.8 million grant was recently announced by the South Australian Government for the development of a world-leading no- and low-alcohol (NOLO) wine production capability. This funding will enable industry to undertake pilot-scale production of new NOLO products and better understand the market opportunities in this growing consumer segment. The program funded by the grant will be delivered by the AWRI, the University of Adelaide, Wine Australia and Australian Grape & Wine and is structured as four pillars:

Pillar 1 – Establishment of a pilot/trial-scale production facility
Pillar 2 – Process and sensory optimisation
Pillar 3 – Market optimisation
Pillar 4 – Regulatory framework

The AWRI will be directly involved in Pillar 1 (led by WIC Winemaking Services) and Pillar 2 (led by Dr Wes Pearson, Dr Simon Nordestgaard and Dr Josh Hixson). For more information, contact enquiries@awri.com.au.

Smoke background data published

When grapes are analysed to assess the risk of smoke exposure, the marker compounds used are a selection of volatile phenols and their glycosides. However, these compounds are also present naturally at trace levels in non-smoke-exposed grapes, which can complicate the interpretation of smoke analysis results. To address this, the AWRI collected data on the trace levels of smoke marker compounds in non-smoke exposed grapes of 12 varieties across Australia over four vintages. The grapes were fermented to wine and the concentrations of marker compounds in the wines were also added to the database. Analytical results for grapes or wine can be compared to the background levels database to determine the likelihood of smoke exposure. This work has recently been published as an open access article in the Australian Journal of Grape and Wine Research. The AWRI is working on expanding the background levels database to 16 varieties and data for additional varieties will be collected this vintage.

Vintage trials underway

As vintage 2022 kicks off around Australia, AWRI researchers are also busy setting up this year’s crop of vintage trials, which form an important part of many research projects. Some of the goals of this year’s trials include:

  • characterising the relationship between air flow rates, dissolved oxygen concentration and ferment redox state, as the next step in the AWRI’s work on aeration of ferments
  • assessing the influence of different yeast strains and diammonium phosphate (DAP) additions on the production of ‘flint’ character associated with the compound phenylmethanethiol
  • investigating the effect of different levels of solids (low, medium and high) in Chardonnay from a warmer region and a cooler region, using a high- and a low-ethyl ester-producing yeast strain, to optimise the expression of ‘peach’ character.

The AWRI thanks all the industry collaborators involved in these and other trials and looks forward to sharing the results. For more information on any of these trials, please contact enquiries@awri.com.au.

Resources on scale and sooty mould

A number of regions across Australia have recently reported issues with scale insects on vines and associated sooty mould on grape bunches. Scale insects are common in Australian vineyards but typically do not cause enough damage to warrant action to control them. In some circumstances, however, the population can reach a threshold where intervention is required to avoid fruit being downgraded or rejected. The AWRI’s page on scale insects and sooty mould provides a range of useful resources, including fact sheets, articles and a webinar detailing a red wine trial conducted in 2017 with sooty-mould-affected grapes. For more information or assistance, contact the AWRI helpdesk on helpdesk@awri.com.au or 08 83136600.

Latest information on sensors and automation

AWRI Senior Engineer, Simon Nordestgaard, has been keeping his finger on the pulse of developments in tank instrumentation and has conducted trials of some of the latest sensors that can help to automate manual processes. He published updates on this work in two recent articles in the Australian & New Zealand Grapegrower and Winemaker, with the first focusing on automated ways to measure ferment density and liquid volume, and the second covering new options for measuring H2S in ferments. This vintage, Simon will be extending this work, focusing on density measurements in red ferments and yeas cultures.

Sustainable Winegrowing Australia Impact report – coming soon

Sustainable Winegrowing Australia will soon release its first ‘Impact Report’ – summarising data collected by the program to demonstrate how Australian grapegrowers and winemakers are working to continuously improve their sustainability practices. The report will include data for vineyard and winery members across six key focus areas: Land and Soil, Water, Energy, People and Business, Biodiversity and Waste. Members of the program will be emailed a copy of the report first and it will then be made available from http://sustainablewinegrowing.com.au by mid-March.

Order the latest staff publications online

Accessing the latest AWRI publications is easy. Visit the AWRI Publications web page to:

  • View the 10 most recent AWRI staff publications and order the articles online from the AWRI Library
  • Search the staff publications database
  • Read the full-text of ‘Technical Notes’ from Technical Review (PDF format)
  • Read the full-text of ‘AWRI reports’ and ‘Vineyards of the world columns’ published in Wine & Viticulture Journal (PDF format)
  • Read the full text of ‘Ask the AWRI columns’ published in Australian & New Zealand Grapegrower & Winemaker

The AWRI’s most recent publications are listed below.

2263 Mierczynska-Vasilev, A., Vasilev, A., Reilly, T., Bindon, K., Vasilev, K. Fluorescence sensing technology for the rapid detection of haze-forming proteins in white wine. Food Chem. 374: 131770; 2022.

2264 Cruz, F.C.S., Habili, N., Wu, Q., Sagarino, R.B., Randles, J.W. Detection of ‘Candidatus Phytoplasma luffae’ in sponge gourd, bitter gourd, and bamboo from Laguna in Luzon, Philippines. Philipp. Agric. Sci. 104(2): 181-185; 2021.

2265 Barter, S., Siebert, T., Bramley, R., Herderich, M., Krstic, M. Better late than never: the formation of distinctive pepper aromas in cool-climate Shiraz. Wine Vitic. J. 37(1): 35-37; 2022.

2266 Dry, P. Inzolia. Wine Vitic. J. 37(1): p. 68; 2022.

2267 Krstic, M. The Australian Wine Research Institute: Annual Report 2021. Aust. N.Z. Grapegrower Winemaker (695): 88-91; 2021.

2268 Krstic, M.P., Culbert, J.A., Parker, M., Herderich, M.J. Smoke taint and climate change. Reynolds, A.G. (ed.) Managing wine quality. Volume 1: Viticulture and wine quality. 2nd Edition: Cambridge, MA ; Oxford, UK : Woodhead Publishing. (Chapter 17.4): 763-778; 2021.

2269 Nordestgaard, S. Beyond Baumé rounds and tank dips. Aust. N.Z. Grapegrower Winemaker (695): 76-81; 2021.

2270 Schmidt, S., Holdstock, M. Ask the AWRI: Aerating red ferments. Aust. N.Z. Grapegrower Winemaker (695): 53-54; 2021.

2271 Wilkinson, K.L., Ristic, R., McNamara, I., Loveys, B., Jiang, W., Krstic, M. Evaluating the potential for smoke from stubble burning to taint grapes and wine. Molecules 26(24): 7540; 2021.

2272 Espinase Nandorfy, D., Siebert, T., Watson, F., Keast, R., Francis, I.L. Understanding the interactive effects of volatile compounds contributing to ‘stone fruit’ aroma nuances in white wines. Aust. J. Grape Wine Res. doi: 10.1111/ajgw.12540 : 1-15; 2021.

2273 Onetto, C.A., Costello, P.J., Kolouchova, R., Jordans, C., McCarthy, J. Schmidt, S.A. Analysis of transcriptomic response to SO2 by Oenococcus oeni growing in continuous culture. Microbiol. Spectr. 9(2): e01154-21; 2021.

2274 Sawyer, S., Longo, R., Solomon, M., Nicolotti, N., Westmore, H., Merry, A., Gnoinski, G., Ylia, A., Dambergs, R., Kerslake, F. Autolysis and the duration of ageing on lees independently influence the aroma and composition of traditional method sparkling wine. Aust. J. Grape Wine Res. 28(1): 146-159; 2022.

2275 Villarreal, P., Villarroel, C., O’Donnell, S., Agier N., Quintero-Galvis, J., Peña, T., Nespolo, R., Fischer, G., Varela, C., Cubillos, F. Late Pleistocene-dated divergence between South Hemisphere populations of the non-conventional yeast L. cidri. Authorea. DOI: 10.22541/au.164182824.45750907 /v1: 2022.

2276 Cordingley, B. Ask the AWRI: Sacrificial yeast cultures for SO2 reduction. Aust. N.Z. Grapegrower Winemaker (696): 52-53; 2022.

2277 Keast, R., Liem, G., Francis, L., Nandorfy, D. Food files: unravelling the flavour of white wine. Food Aust. 74(1): 30-31; 2022.

2278 Dixon, R. Ask the AWRI: How to tame an unruly canopy. Aust. N.Z. Grapegrower Winemaker (697): 54-57; 2022.

2279 Coulter, A., Baldock, G., Parker, M., Hayasaka, Y., Francis, I.L., Herderich, M. Concentration of smoke marker compounds in non-smoke-exposed grapes and wine in Australia. Aust. J. Grape Wine Res. doi: 10.1111/ajgw.12543 : 1-16; 2022.

2280 Nordestgaard, S. Measuring stinky ferments in situ. Aust. N.Z. Grapegrower Winemaker (697): 62, 64-68, 70-71; 2022.

Acknowledgements

The AWRI acknowledges support from Australia’s grapegrowers and winemakers through their investment body, Wine Australia, with matching funds from the Australian Government. The AWRI is a member of the Wine Innovation Cluster in Adelaide, South Australia.

Technical Review February 2022 issue available online

17 February 2022 >

The February 2022 issue of Technical Review is now available online. Articles and abstracts can be viewed individually, or the full issue can be downloaded. The online format of Technical Review allows you to browse the list of the latest articles on grape and wine production by keyword, view article summaries, read full-text articles from open access journals and order journal articles (not available for open access) from the AWRI Library.

For copyright reasons, access to abstracts is available only to Australian winemakers and grapegrowers who pay the Wine Grapes or Grape Research levies. The technical notes authored by the AWRI are, however, freely available. If you have forgotten your password for the AWRI website, please use the forgotten password link to reset your password.

Below is a snapshot of what's in this issue:

AWRI Technical Notes
AWRI publications
Current literature – oenology
Current literature – viticulture

Top tasting skills rewarded

7 February 2022 >

7 February 2022

The Australian Wine Research Institute (AWRI) announced today that Ben Cane was the dux of the 52nd Advanced Wine Assessment Course.

Christmas closure and support during the break

20 December 2021 >

The AWRI will be closed over the Christmas/New Year period from midday on Friday, 24 December and will re-open at 8:30am on Tuesday, 4 January 2022.

AWRI Commercial Services
The Commercial Services laboratories will be closed from midday on Friday, 24 December and will re-open at 9:00am on Monday, 10 January 2022.

Industry support
Telephone and email support will be available during the office closure. If you require assistance over the holiday period, please contact:

Library
The John Fornachon Memorial Library will be closed from midday on Friday, 24 December and will re-open at 9:00am on Tuesday, 4 January 2022. Access to the library’s online database will continue to be available 24 hours a day, 7 days a week via the AWRI website.

eNews – December 2021

17 December 2021 >

Best wishes for the festive season and vintage 2022

Vale Randell Taylor

Resources on wet weather conditions

Still seeking reductive white wines

AWRI decanted season 1

Aeration workshop recording available

Sustainable Winegrowing Australia update

Order the latest staff publications online

Acknowledgements

Have you listened to AWRI decanted?

The AWRI wishes everyone in the grape and wine community a safe and happy festive season, with a chance to relax and recharge before vintage 2022. We look forward to working with you next year.

Vale Randell Taylor

All of us at the AWRI have been incredibly touched by the many kind messages received from across our industry since the tragic death of our friend and colleague Randell Taylor on 27 November. Randell had served the AWRI and the grape and wine industry for more than 25 years. He was known and respected for his expertise in trace analysis of wine, but is remembered most for his infectious smile, positive energy and incredible zest for life. We are devastated by his loss and will miss him enormously. An online tribute board has been created where people can share photos and memories of Randell: https://www.kudoboard.com/boards/vpiEOvWM

Resources on wet weather conditions

The Bureau of Meteorology declared a La Niña event on 23 November 2021, which was not a surprise to many parts of Australia already been experiencing wet and cool weather. A wide range of resources including eBulletins and webinar recordings are available to help growers and winemaking dealing with wetter conditions and the associated disease risks:

Still seeking reductive white wines

Do you have a white wine with a reductive character? The AWRI and Charles Sturt University are working on a study to better understand copper addition practices and ‘reductive’ aromas in white wine. A large number of white wines with some degree of reductive aroma are needed for analysis. The researchers leading this study would greatly appreciate if producers could provide examples of wines with sulfide-related aromas. All information regarding the wines will be treated with the utmost confidentiality and no reference to producers will be made. Only information regarding the variety, region, and vintage will be included in the study. This work ultimately aims to provide winemakers with tangible guidance on the best practice use of copper and how to prevent ‘reductive’ aroma formation in white wine. Please contact Dr Marlize Bekker (marlize.bekker@awri.com.au) if you can help or for more information.

AWRI decanted season 1

The first season of the AWRI’s podcast wrapped up recently, with an episode featuring Matt Zadow from Yalumba’s Oxford Landing Winery. Matt shared his experiences adding oxygen to red ferments and the benefits he is seeing from this practice. This was a great follow-up to the previous episode where Dr Simon Schmidt discussed the AWRI’s research on oxygen use in winemaking. All seven episodes of season 1 are available on the major podcast apps (e.g. Apple, Spotify) and via the AWRI website. Season 2 will go to air after vintage. Subscribe to AWRI decanted in your podcast app to be notified when new episodes are available.

Aeration workshop recording available

On 30 November the AWRI hosted an online workshop on aeration of red ferments, the recording of which is now available on the AWRI’s YouTube channel. This workshop was designed for both winemakers who currently use aeration during fermentation and those who would like to try it next vintage. It covers the equipment needed, how to set it up and use it, as well as insights into technology for measuring oxygen during fermentation. Presenters include Luke Wilson (Yalumba Wines), Jeremy Nascimben (Calabria Wines), Prof. Roger Boulton, University of California, Davis, USA and Anthony D’Onise (Windowrie Wines). For further information or assistance with adopting aeration of red ferments, contact the AWRI helpdesk team on helpdesk@awri.com.au or 08 8313 6600.

Sustainable Winegrowing Australia update

Thanks to support from across Australia, Sustainable Winegrowing Australia is continuing to grow and now has more than 800 members in 48 wine regions. Demand for certification is also increasing with more wine labels carrying the trust mark and more signs going up around the country. If you’re certified, we’d love to receive a photo of your sign to add to our gallery. If you’re thinking of a creative way to use the trust mark, remember to check the rules and style guide and get in touch (helpdesk@awri.com.au) for assistance.

The AWRI sustainability team has been extremely busy over the past few months delivering certification training to more than 400 members of Sustainable Winegrowing Australia across 31 regions. Participants at these workshops rated the usefulness of these workshops at 98% and more than half said that they’d take the information they heard and change their practices in their vineyards and wineries. Attendance at a certification training workshop is the first step towards becoming a certified member. These workshops deliver everything needed for growers, winemakers and wine businesses to interpret and implement the program for the best outcomes at audit and ongoing program management. If you would like to participate in an upcoming certification workshop, please complete the expression of interest form here.

Order the latest staff publications online

Accessing the latest AWRI publications is easy. Visit the AWRI Publications web page to:

  • View the 10 most recent AWRI staff publications and order the articles online from the AWRI Library
  • Search the staff publications database
  • Read the full-text of ‘Technical Notes’ from Technical Review (PDF format)
  • Read the full-text of ‘AWRI reports’ and ‘Vineyards of the world columns’ published in Wine & Viticulture Journal (PDF format)
  • Read the full text of ‘Ask the AWRI columns’ published in Australian & New Zealand Grapegrower & Winemaker

The AWRI’s most recent publications are listed below.

2261 Xing, F., Gao, D., Habili, N., Wang, H., Zhang, Z., Cao, M., Li, S. Identification and molecular characterization of a novel carlavirus infecting rose plants (Rosa chinensis Jacq.). Arch. Virol. doi: 10.1007/s00705-021-05260-2: 1-4; 2021.

2262 Longbottom, M. Ask the AWRI: Carbon accounting. Aust. N.Z. Grapegrower Winemaker (694): 44-45; 2021.

Acknowledgements

The AWRI acknowledges support from Australia’s grapegrowers and winemakers through their investment body, Wine Australia, with matching funds from the Australian Government. The AWRI is a member of the Wine Innovation Cluster in Adelaide, South Australia.

Technical Review December 2021 issue available online

16 December 2021 >

The December 2021 issue of Technical Review is now available online. Articles and abstracts can be viewed individually, or the full issue can be downloaded. The online format of Technical Review allows you to browse the list of the latest articles on grape and wine production by keyword, view article summaries and order journal articles from the AWRI Library.

For copyright reasons, access to abstracts is available only to Australian winemakers and grapegrowers who pay the Wine Grapes or Grape Research levies. The technical notes authored by the AWRI are, however, freely available. If you have forgotten your password for the AWRI website, please use the forgotten password link to reset your password.

Below is a snapshot of what’s in this issue:

AWRI Technical Notes
AWRI publications
Current literature – oenology
Current literature – viticulture

Statement – Sustainable Winegrowing Australia legal proceedings

22 November 2021 >

The Australian Wine Research Institute advises members and stakeholders of Sustainable Winegrowing Australia that legal proceedings have been commenced by Dr Irina Santiago-Brown, in the Sydney Registry of the Federal Circuit and Family Court of Australia, against the AWRI and Australian Grape & Wine.

Downy mildew update

18 November 2021 >

Issued: 18 November 2021, updated 19 November 2021

Recent weather conditions have been conducive to downy mildew infection and symptoms of the disease have been reported in some regions. This eBulletin provides a reminder about downy mildew control.

CHEMICALS REGISTERED FOR USE
The recommendations section of Agrochemicals registered for use in Australian Viticulture 2021/2022 (‘Dog book) lists the active constituents registered for downy mildew control in Australian viticulture that can be used on grapes destined for export wine. The restrictions on use are imposed to ensure that the chance of residues is minimal. A list of all the active constituents registered for downy mildew control can be found on the AWRI online search portal here.
Phosphorous acid and captan are active constituents that are not currently (2021/22) accepted for use on grapes for export wines. The use of phosphorous acid is discussed on the AWRI’s phosphorous acid webpage.

MANAGING THE DISEASE
There are two main types of downy mildew fungicide, classified according to their timing in relation to infection events (pre-infection and post-infection), which also describes when they are most effective.

Pre-infection fungicides (protectants)
These protect the vine by preventing infection. Some protectant fungicides are taken into the grapevine tissue, but most provide a protective barrier on the surface of the foliage where they stop spores germinating. Since downy mildew invades through the stomates, contact fungicides should be applied to cover the undersides of leaves – the most difficult place to spray. They must be re-applied prior to an infection event if there is sufficient growth of leaves or of developing berries. Sprays should be applied as close as possible before infection events while allowing time for the spray to dry. Access to forecasts of downy mildew events will help time these sprays best.

Post-infection fungicides (eradicants)
These kill the pathogen inside infected tissue if they are applied at the right time. They do not eradicate the disease from the vineyard but, being systemic, are quickly absorbed into the sprayed foliage and are ‘rain fast’ within two to three hours of spraying.

The post-infection fungicides are more expensive but are able to stop the downy pathogen from within infected tissue, provided they are applied before oil spots appear. Consequently, these fungicides should only be applied when needed, as soon as possible after an infection and before oil spots appear (i.e. in warm conditions, within five days post-infection). In cool conditions oil spots may take three weeks to appear, so the monitoring period needs to be extended. Like all fungicides, good coverage is important.

The post-infection fungicides include metalaxyl and metalaxyl-M (Group 4) and phosphorous acid (Group 33). Because metalaxyl and metalaxyl-M are mixed with mancozeb or copper (protectants) these mixtures simultaneously provide a protective shield against new infection while treating infected tissue. However, as post-infection fungicides are single-site ‘actives’ and sprayed while the disease is present, they are at a high risk for resistance development. Resistance to metalaxyl and metalaxyl-M (Group 4) has been detected in Australian vineyards. Follow resistance management guidelines in the ‘Dog book’.

Spray timing
In wet seasons, weather conditions may prevent sprays from being applied when desired. Protectant fungicides should be applied to restrict the disease from getting established. Growers may need to shorten the window between protectant applications if weather conditions promote disease development and active growth is occurring. Relying on curative agrochemicals will not work if sprays cannot be applied. In low disease pressure years, timing sprays in relation to primary and secondary infection events may be a viable strategy. For this to work, growers need to monitor weather forecasts and at predicted times of high disease risk spray before the disease develops. Monitoring and interpreting the weather that follows is important to determine if infection occurred and adjust spray type and timing accordingly. If available, seek assistance from regional disease alert services.

Checking spray efficacy – the ‘bag test’
The efficacy of sprays can be checked by ‘bag testing’ oil spots to see if the downy mildew is still active. The bag test aims to stimulate sporulation conditions and involves putting the oil spot leaf in a ziplock plastic bag with a moist tissue and storing it at room temperature (ideally above 13°C) in a drawer overnight. If fresh sporulation (down) is present on the underside of the oil spot the following morning then the downy mildew is still active. Sometimes, the centre of the oil spot is dead but the margins can still remain active. Conducting bag tests on multiple oil spots from across the vineyard can provide a good picture as to whether the downy mildew is active or not.

Important considerations when spraying

  • Spray coverage is critical for good control. It’s important to calibrate sprayers and check coverage. Make sure the water volume applied is sufficient to wet the entire canopy to the point of run-off. Sunscreen products can assist in assessing spray coverage on all tissue including hard to reach targets such as inflorescences.
  • Confirmed resistance to metalaxyl has been identified in some regions. This is the result of ongoing use in high pressure sites after an infection (i.e. as an eradicant). The key lesson is that if you can’t apply metalaxyl immediately post-infection (i.e. prior to oil spots), you shouldn’t use it.
  • To be effective, a post-infection spray must go on a dry canopy. A canopy carrying moisture will not take up the chemical and will not provide adequate control. Cultural practices such as trimming to allow more air into the canopy to assist with drying can help reduce disease pressure and improve coverage on remaining and new foliage.
  • Flowers, caps and anthers hold water for longer than leaves. This means they can meet the conditions for infection even if the leaves appear dry and are no longer susceptible. To reduce primary infection conditions, cultural practices such as trimming allow more air into the canopy to assist with drying.
  • Reduce spray intervals in high pressure seasons to maintain protection. Copper sprays at 10-12 day intervals are recommended while the vines are growing strongly and rain persists. Vines can ‘grow out of cover’ at longer intervals of 14 days, allowing downy mildew a chance to infect unprotected new growth.

PHOSPHOROUS ACID
Phosphorous acid is a registered fungicide with post-infection capabilities, but residues in wine are to be expected if it is used at any time during the growing season. For this reason, some exporting wineries have no tolerance for fruit that has been treated with this active ingredient. The ‘Dog book’ recommendation states that phosphorous acid should not be applied to fruit destined for export wines. Growers should contact their winery or grape purchaser prior to any phosphorous acid application.

Information about the tolerance for phosphorous acid residues in different markets can be found on the AWRI’s phosphorous acid webpage.

ADDITIONAL RESOURCES ON DOWNY MILDEW:

ACKNOWLEDGEMENTS
Liz Riley, Vitibit and Andrew Taylor, WA Department of Primary Industries and Regional Development are thanked for their contributions to this eBulletin.

For more information or assistance, please contact the AWRI helpdesk on 08 8313 6600 or helpdesk@awri.com.au.

Managing disease in wet conditions

12 November 2021 >

12 November 2021

Most grapegrowing regions across Australia have experienced some rainfall in the past week. The Bureau of Meteorology has maintained the ENSO (El Nino-Southern Oscillation) Outlook at La Niña ALERT. The chance of a La Niña forming in the coming months is around 70%, or roughly three times the normal likelihood of an event forming in any year. For grapegrowers, La Niña events typically mean increased rainfall and cooler daytime temperatures. A cooler than normal summer is forecast for some parts of eastern Australia, but for other parts a hotter or average summer is forecast. Refer to the Bureau’s latest climate outlook video.

Control of fungal disease is much more challenging in wet seasons, which means it is even more important to get the most out of every spray. The 4Ts of effective spray application are a good reminder of how to do this.

TIMING: Time spray applications to coincide with the most vulnerable life cycle stages of the target disease or when the disease is most destructive. Grapevine flowers are very susceptible to Botrytis and should be protected when conditions favour the disease. Downy mildew and powdery mildew are a threat to any unprotected green tissue, which means that rapid leaf expansion can dilute the protective cover last applied. It may be necessary to shorten spray intervals at times of rapid growth to ensure grapevine tissue is adequately protected. Heavy rainfall or multiple wet days can restrict vineyard access. Consider spraying ahead of wet weather to make sure you can get protective sprays on as required. Spraying in windy conditions is not recommended as it can affect spray coverage and cause off-target impacts.

TARGET: Focus your efforts on making sure you are delivering sprays to the target. It is not easy to get good coverage of all plant tissue, but it is the best chance you have of managing diseases when pressure is high. In low pressure years, this is less important because the climatic conditions (temperature, UV, low humidity) are helping to manage diseases. Sunscreen products can assist in assessing spray coverage on all tissue including hard to reach targets such as inflorescences. Mix up a partial tank, spray a part row, allow a few minutes to dry, assess coverage, adjust sprayer as needed to improve coverage (see TECHNIQUE) and repeat.

TREATMENT: The type and amount of chemical (the treatment) must be appropriate for the pest target. Follow the chemical label instructions with regards to rates and be aware of CropLife resistance management strategies. If you have relied heavily on a few chemical groups in the past, choose a new chemical group. Make sure you are using the appropriate concentration factor if you are doing concentrate spraying – underdosing will result in failure to control and may increase the risk of fungicide resistance.

TECHNIQUE: Good technique involves sprayer adjustment, calibration and evaluation of spray performance using a method to test coverage such as wettable paper or the addition of a sunscreen product (as described in TARGET above). Consider adjustments to:

  • nozzle type, operating pressure, distance from the canopy and direction
  • air volume, speed, and direction
  • water volume applied to the canopy
  • ground speed of the sprayer.

Additional resources on spray application

For more information or assistance, contact the AWRI helpdesk on helpdesk@awri.com.au or 08 8 313 6600.