Evaluation of second-generation disease resistant grapevines developed by CSIRO

Summary

Objective

This project aims to carry out field evaluation of approximately 500 second-generation mildew-resistant varieties produced in the CSIRO grapevine breeding program. Single vines established in Griffith (warm) and Orange (cool) vineyards will be assessed for their viticultural performance and wine quality over three vintages to 2028. The 20 ‘best’ reds and whites will be selected for replicated evaluation in subsequent projects, with the best-performing lines progressed to commercial release. This project will also continue to support the ongoing evaluation and adoption of first-generation disease-resistant varieties by the Australian wine industry until the new second-generation varieties become available.

Background

The premium winegrape varieties used for the production of Australian wine do not have significant resistance to the major vineyard pathogens – powdery mildew or downy mildew. As a result, grape growers are totally dependent on the frequent application of fungicides to control these diseases. Long-term Wine Australia investment with CSIRO (CSP 0904) has resulted in the breeding and selection of new first-generation mildew-resistant varieties, containing one gene each for powdery and downy mildew resistance. These selections were planted in replicated trials in Irymple, Wagga Wagga and Orange to assess vineyard performance and wine quality (CSP 1303 & CSA 1701-1.6). A number of these first-generation selections are now under commercial evaluation by growers and wine companies.

In Wine Australia project CSA 1701-1.1, marker-assisted selection was used to produce second-generation mildew-resistant varieties, which have two genes each for downy and powdery mildew resistance. In addition, the red-flesh locus from the grape variety Dunkelfelder was introgressed into some of the red selections to produce varieties that have not only durable mildew resistance but also elevated levels of anthocyanin production to address the challenge of producing red wines with acceptable colour under increasing temperatures caused by climate change. Initial evaluation was carried out as per the first-generation varieties, with 552 second-generation mildew-resistant progeny established in an unsprayed block of the SARDI research station in Nuriootpa. These were progressively planted from March 2019 to February 2022 as part of project CSA 1701-1.1, and were subject to one year of field performance monitoring and wine evaluation (selected lines).

Research approach

Initial activities will focus on vineyard establishment at unsprayed NSW DPI sites in Griffith (warm) and Orange (cool). Prior to the commencement of this project, a selection of 357 second-generation lines showing vigorous growth since planting at Nuriootpa were moved to both sites. Another 43 second-generation varieties were judged to be too young to collect suitable canes (having only been planted in February 2022) and will need to be allowed to grow for another season before canes can be collected in 2023. In addition, there are another 116 second-generation varieties that are currently maintained in a glasshouse at CSIRO on the Waite Campus that will also be sent to Griffith for planting.

Vines will be trained to the fruiting wire to establish cordons and will be pruned to 18-20 buds per metre of cordon for fruit production. Vines will be assessed for the following:

• resistance to powdery and downy mildew
• key phenology dates – budburst, flowering, veraison and harvest
• bunch weight and architecture, berry weight and berry chemistry at harvest
• pruning weights.

Selections showing acceptable yield and fruit characteristics (i.e. good acid at harvest) will be processed at Charles Sturt University winery using micro-scale ferments, in the same way that the first-generation vines were assessed in Wine Australia project CSP 0904. The micro-scale wines will then be evaluated by winemakers for aroma, flavour intensity and flavour uniqueness. 

The data for each single vine will allow the 500 or so varieties to be narrowed down to an elite selection of around 20 reds and 20 whites for commercial evaluation in replicated trials.