Grapevine red blotch-associated virus M. R. Sudarshana, USDA-ARS

Virus facts

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  1. Grapevines host the largest number of viruses known to infect a crop plant and some of the viruses identified in grapevines infect solely Vitis species.  
  2. There are more than 85 recognised virus and virus-like diseases of grapevines worldwide.
  3. The first grapevine virus seen under an electron microscope was grapevine fanleaf virus almost 60 years ago. This virus is considered eradicated from Australia and is a quarantine pest.
  4. In the 1930s it was widely believed that phylloxera was responsible for transmitting grapevine fanleaf virus. In the 1950s it was determined that the dagger nematode Xiphinema index was the vector for transmission.
  5. Australia has 10 endemic grapevine viruses. The group of grapevine leafroll-associated viruses (GRLaV) are considered to cause the most economic damage.
  6. Viruses can be difficult to diagnose, and the damage they cause can be unpredictable. Some severely damage grapevines and others cause no damage.
  7. Viruses can be spread by insect vectors, soil-borne nematode vectors or by using infected cuttings during grafting and propagation.
  8. The best way to prevent grapevine viruses is to start with high quality planting material that’s been cleared of damaging viruses by pathogen testing.
  9. Controlling potential virus vectors such as mealybugs, scale insects and nematodes is key to virus control. Most viruses occurring in Australia are not transmitted on pruning equipment or by touch.
  10. Farm-gate hygiene is key to virus management. Start work in the cleanest part of your vineyard and finish with virus-affected areas.
  11. After you’ve been into a known or suspected virus area of a vineyard, clean machinery and equipment thoroughly of soil and plant material to limit virus spread. This also prevents transmission of other pests, diseases and weeds.
  12. Virus symptoms can easily be confused with other vine health issues. You should get your vines tested if you see anything unusual.
  13. Some grapevines do not show symptoms from virus infection and are termed “asymptomatic”. These vines act as a host for virus which can then be transmitted to symptomatic vines by vectors.