Grapevine viruses can shorten the life of infected grapevines and reduce both the quality and yield
of grapes. Several viruses, especially those belonging to ‘rugose wood complex’, have been
associated with graft incompatibility. In some cases, especially in many white grape varieties and
non-vinifera rootstocks, virus-infected vines do not show symptoms but the virus can spread to
susceptible neighboring vines and vineyards. Virus testing is also a useful tool to help diagnose poor-performing grapevines and to detect and eliminate infections before they become a serious problem.
The reason for testing grapevines determines the best approach for sampling for virus testing. If
symptoms have been observed, or are suspected, samples taken directly from the affected vine
should be submitted for testing. However, if a vineyard block is being tested as a precautionary
measure, it is important to ensure that a fair representation of the block is sampled. Vineyard blocks
often vary greatly in size and collecting a sample representative of the entire block can be challenging.
Recommended sampling procedure:
The most accurate virus detection is possible when samples are taken in spring, autumn or winter. Avoid sampling in the height of summer or on very hot days, as viruses become less active in hot conditions and virus concentration may be reduced to an undetectable level.
At a minimum, randomly select five vines for every 1,000 vines spread across the block, to ensure an accurate representation of the area tested. Tag the vines so they can be identified later.
From each of the vines, cut a minimum of two 20-30 cm sections of canes (dormant season), or green shoots (in season). The second node on either side of the trunk is an ideal location.
If samples are being pooled, ensure that canes from no more than five vines are collated.
Ensure grapevine cuttings are clearly labelled, free of soil deposits and placed in a labelled sealable plastic bag. For samples leaving a biosecurity risk area, ensure that samples are double bagged, and the required quarantine standards are met.
Send cuttings as soon as possible, ideally within one to two days, to prevent them from drying out.
Ensure that samples have all the required documentation (especially if the samples are going interstate) to prevent delays in quarantine. A checklist is provided at the end of this fact sheet with details of required information.