Grapevine Red Blotch Virus

Red blotch disease is caused by a virus known as grapevine red blotch virus (GRBV) or grapevine red blotch-associated virus (GRBaV), a single-stranded circular DNA virus. The virus is a member of the genus Grablovirus.

The virus creates red blotches on the leaves and causes a decreased sugar level in grapes of up to 5° Brix as well as increased acidity

Red blotch can delay berry ripening, alter berry colour and reduce berry size. It can also affect pH, anthocyanin and tannin levels as well as other phenolic factors that overall reduce the quality and potential market value of wine made from infected grapes.

In red grape varieties, the blotches are red, while in white grape varieties, blotches may not appear as dramatic and be pale green to pale yellow.

If you suspect the virus:
Please call the laboratory to discuss how to submit your sample on 1800 675 623 or email:

Laboratory hours are 8:30 am to 4:30 pm Monday to Friday. Specimens must be packaged correctly to ensure that the plant remains intact. Wrap plant samples in slightly damp newspaper to help maintain freshness. Do not package plant material in plastic bags during summer.

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