Determination of cultivars amenable to visual assessment for leafroll evaluation

by | Jan 24, 2022 | Winetech Scan

Researcher: Prof G Pietersen, Pathosolutions

Aim and industry relevance:

ELISA tests for grapevine leafroll associated virus type 3 (GLRaV-3) using petioles are currently being done within a small, prescribed testing window starting on 1 March to when petioles drop in any given season, as this is the generally accepted optimal time of year for GLRaV-3 detection.  This creates a limit on the number of ELISA tests which can be done. To free-up resources in this period, some red cultivars with high correlations between symptoms and ELISA tests are only assessed visually by trained inspectors (Cultivars include Cabernet Sauvignon, Shiraz, Merlot and Cabernet franc). The aim of this project is to expand upon the list of red cultivars which can be tested visually only, by determining the correlation between ELISA tests and symptoms. This will allow for more tests to be conducted on cultivars where the tests are more acutely required (white cultivars).

The outcome of this correlation can be taken up within the grape certification scheme as a prescript. This will make it possible for all Plant Improvement Organisations to inspect those cultivars where symptoms correlate very well with ELISA, rather than having to conduct ELISA tests. Reduced obligate ELISA tests will free up the time period in which to conduct ELISA tests on cultivars where symptoms are not present/obvious.

Image credit: P.G Goussard

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