Virus-Free Vineyards – The BlogFeed for this Blog
Unlike red varieties, which reliably express visual symptoms of Leafroll 3 infections, white varieties present an additional challenge to vineyard managers’ attempts to control the spread of the virus. While some leaves on some white-variety grapevines may express similar visual symptoms, they are not a reliable indicator of infection – and many vines will show no symptoms at all.
Sauvignon Blanc tested 'positive' for Leafroll 3
Sauvignon Blanc tested 'negative' for Leafroll 3
Instead, statistical screening – involving the collection of leaf or cane samples and laboratory ELISA testing – is used to provide information about the percentage of infection in a block.
‘ELISA’ is short for ‘Enzyme-linked ImmunoSorbent Assay’ – a type of laboratory test that uses the reaction of an antiserum (antibody) to verify the presence of a disease, including Leafroll 3. ELISA tests are accurate, fast and relatively inexpensive compared with other testing methods used on grapevines.
Results from statistical screening provide useful information related to the disease status of a vineyard, and the method is used increasingly in connection with purchasing decisions.
New Zealand Winegrowers’ Virus Elimination Project has prepared a new fact sheet, outlining the steps involved in testing white varieties for Leafroll 3. The instructions are easy to understand, and links are provided to each of the laboratories accredited by IANZ for the testing procedure.
You can download ‘Testing white varieties for Leafroll 3’ from this page – look for the box entitled ‘Fact Sheets’ on the lower right.
We have also updated our fact sheets on ‘Leafroll symptoms on red varieties’ and ‘Vine removal on Leafroll 3’ to include guidelines developed from data analysed by Vaughn Bell, a scientist at Plant & Food Research and a key member of our project.
The time for monitoring visual symptoms of Leafroll 3 on red varieties is now. Our Flickr photo library, showing symptoms on individual red varieties (Cabernet Sauvignon, Malbec, Merlot, Pinot Noir and Syrah) has received more than 7,000 unique views to date - a number that's literally growing every day. The library provides a helpful catalogue of visual symptoms ranging from individual leaves to entire vines, and we hope many more of you will access this tool during the present monitoring period.
New Zealand Winegrowers’ Virus Elimination Project has completed a seven-part video series, outlining the key steps to controlling Leafroll 3 Virus in vineyards.
The series, presented by project manager Nick Hoskins, covers essential topics including:
- Early-season mealybug control
- Symptom monitoring on red varieties
- Mealybug monitoring
- Removal of infected vines
- How to plant and treat replacement vines
The videos have been posted on the members area of NZW’s YouTube channel and can be accessed here after signing in.
Part of New Zealand Winegrowers’ Virus Elimination Project, the ‘Virus-Free Vineyards’ blog recently celebrated its first anniversary. Updated regularly by project team members, the blog’s first year of posts covered a wide range of topics related to the control and elimination of Leafroll 3 Virus and its main vector – mealybugs:
- Seasonal ‘how to’ information for vineyard managers.
- Short updates on field trials in participating vineyards.
- Links to pertinent international research and case studies.
In case you missed one or more of our earlier posts, we’ve created an annual index below, including the links to each story published during 2012 and 2013:
- Mealybug Control Part 1 – Early Season Applications
- September 2012
- Mealybug Control Part 2 – Early Season Applications
- October 2012
- Leafroll 3 Virus and Top Grafting
- November 2012
- Craggy Range Case Study
- December 2012
- Recognising Leafroll 3 Symptoms on Red Varieties
- February 2013
- New Photo Library for Leafroll 3
- March 2013
- Is it Leafroll 3 or Magnesium Deficiency?
- April 2013
- Post-harvest Wrap-up
- May 2013
- The Leafroll Virus Index
- June 2013
- Leafroll Disease around the World
- July 2013
- Mealybugs, Marlborough and More
- August 2013
- News from the Virus-fighting Front
- November 2013
- Virus Workshops Questions & Answers
- November 2013
Photo library for symptom monitoring
Finally, don’t forget about our photo library on Flickr. To help you develop your ability to detect symptoms, we’ve posted photographs illustrating Leafroll 3 expression on individual red varieties, including:
- Pinot Noir
- Cabernet Sauvignon
These photos, plus other sets illustrating magnesium deficiency and the difficulty of spotting symptoms accurately on Sauvignon Blanc, can all be accessed at Flickr, and they’ll come in handy in the weeks leading up to harvest in 2014.
Welcome! This blog is maintained by members of the Virus Elimination Project, a New Zealand Winegrowers' Research Project that is co-funded by the Ministry for Primary Industries (Sustainable Farming Fund).
The Virus Elimination Project has three main objectives:
- Identify and map the presence and/or spread of Grapevine Leafroll-associated Virus 3 (Leafroll 3) in participating vineyards in New Zealand.
- Contain and control Leafroll 3 virus and the main vector – mealybugs – through a programme that comprises vine removal/replants, hygiene practices and insect control.
- Develop “best practice” guidelines for New Zealand Winegrowers, with the long-term goal of maintaining virus-free vineyards.
Control and management of Leafroll 3 is a community issue. That’s why the project trains growers to identify leafroll virus, map, treat, and remove infected vines on an area-wide basis in tandem with effective control of mealybugs. We welcome your comments and questions on this blog.
- What is GLRaV-3?
- Leafroll symptoms on red varieties
- What is the Virus Elimination Project?
- What are the commercial costs associated with GLRaV-3?
- Mealybug control for cropping vines
- Mealybugs – knowing the pest
- How to look for mealybugs
- Vineyard hygiene & Leafroll 3
- Vine removal and Leafroll 3
- Vine establishment for replants
- Mapping Leafroll 3
- Pre-harvest mealybug monitoring
- Testing white varieties for Leafroll 3