Have you been looking out for virus symptoms over the past couple of months, whether you’ve been on a harvester, walking rows to collect maturity samples, or fixing irrigation leaks?

In Australia, looking out for virus infection in vineyards has often been synonymous with looking out for ‘Grapevine Leafroll’ symptoms. Although we have approximately 10 endemic grapevine viruses, it’s the leafroll viruses that we are most familiar with spotting in the field. Grapevine Leafroll virus is considered the second most common viral disease globally (Martelli, 2014), and descriptions of this virus were first published in Australia in the 1950’s (Fraser, 1958).

Late summer to autumn is the key time for symptom expression of leafroll viruses and therefore the best time to actively or passively survey your vineyards for signs of this and other viruses. Many varieties can be symptomless and act as a reservoir of virus for other sensitive varieties. 

Viruses can also be mistaken for magnesium or phosphorous deficiencies resulting in potential misdiagnosis. It’s therefore important to validate your observations through diagnostic testing, and to ensure your testing includes both symptomatic and symptomless or asymptomatic vines.

Viruses are commonly spread through infected planting material and grafting, but some viruses are also spread within a vineyard through insect vectors such as scale, mealybug and mites. Ensure you monitor for vectors year round as you are walking or driving through your blocks, so you can gauge potential for vector spread of any viruses present.

At worst, viruses can reduce photosynthetic rate, leaf chlorophyll, shoot length and lignification, yield, grape and wine quality, cause graft incompatibility, vine decline and ultimate death.

If you haven’t considered checking your vines for virus, it’s never too late to test and in most situations, testing can be done year round.

For further information on viruses, refer to Wine Australia’s suite of downloadable virus fact sheets here.

Looking for a grapevine virus testing laboratory?

Crop Health Services, Victoria

Web: http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/diagnostic-services 

Ph: 03 9032 7323 / 03 9032 7515 or email: chs.reception@ecodev.vic.gov.au

AWRI Commercial Services, South Australia

Web: https://www.awri.com.au/commercial_services/virus-testing/ 

Ph: 08 8313 7426 or email: commercialservices@awri.com.au

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References

  1. Fraser, L. 1958. Report on observations on virus diseases of grapevines in the USA and on the occurrence of leafroll and other virus diseases of grapevine in New South Wales. New South Wales Dept. of Agriculture Report, 27 pp.
  2. Martelli, G.P. 2014. Directory of virus and virus-like diseases of the grapevine and their agents. Journal of Plant Pathology 96 (1S): 1–136.

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