Grapevine viruses

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Grapevine viruses are among the most significant long-term threats to vineyard productivity, fruit quality and profitability.

Why grapevine viruses matter

More than 80 virus and virus-like diseases have been identified in grapevines worldwide, with several occurring in Australian vineyards. While some infections produce obvious symptoms, others can remain hidden for years, quietly reducing vine performance and acting as a source of infection for healthy vines.

Unlike many fungal and bacterial diseases, there is no cure for a virus-infected grapevine. Once infected, the focus shifts to management, containment and preventing further spread.

Virus infections can affect:

Vine vigour and canopy development
Yield and bunch size
Fruit composition and ripening
Harvest timing and logistics
Propagation material quality
Vineyard lifespan and profitability

In some cases, yield losses of up to 50% have been reported, along with delayed ripening, reduced colour development and lower sugar accumulation. Virus infections can also affect graft compatibility and increase the risk of vine decline and premature vineyard replacement.

The economic impact is often compounded by the fact that infected vines may appear healthy for several seasons before symptoms become obvious.

How viruses spread

Most grapevine viruses spread through:

Infected propagation material, rootstocks or grafting wood
Grafting and top-working activities
Insect vectors such as mealybugs,scale insects and mites are for some viruses
Some nematode species, depending on the virus

Many viruses can spread through a vineyard long before symptoms become visible. Infected vines may carry and transmit viruses without showing obvious signs of disease, allowing infections to establish and spread before impacts on yield, fruit quality or vine performance become apparent.

Practical management for growers

Effective virus management starts well before vineyard establishment and should be considered whenever planting, replanting, propagating, top-working or redeveloping a vineyard.Use high-health planting material

The most important preventive measure is sourcing certified, virus-tested planting material from accredited programs.

This is particularly important when:

Establishing new vineyards
Replanting missing vines
Top-working existing blocks
Introducing new clones, varieties or rootstocks

Monitor regularly

Routine monitoring helps identify disease early and supports informed replanting and management decisions.

Monitor blocks for:

Changes in vine vigour
Poor or uneven growth
Leaf discolouration and rolling
Delayed ripening
Reduced yield or bunch size
Localised areas of decline

Be aware that virus symptoms can take more than 12 months to appear following infection, and some infected vines may remain symptomless.

Confirm with testing

Visual symptoms alone are not sufficient for diagnosis.

Nutrient deficiencies, environmental stress and other disorders can resemble virus symptoms. Laboratory testing should be used to confirm infections and support management decisions.

Testing is particularly valuable before:

Vineyard redevelopment
Top-working
Establishing nursery blocks
Selecting propagation material

Control insect vectors

Several economically important grapevine viruses are spread by mealybugs and scale insects, while others are spread by mites. Managing these vectors is an important component of virus control.

An integrated pest management approach should be used, including:

Regular monitoring of vineyards for vector activity
Early identification of pest hotspots
Management of vector populations before they become widespread
Use of appropriately registered products when required, applied at the correct timing and with adequate coverage
Protection and conservation of beneficial insects and other natural enemies

More information on virus vector management:

Wine Australia scale insect webpage
Scale insect factsheet
Managing vineyard pests factsheet

Rogue infected vines

Where economically justified, removing infected vines can help slow disease spread and reduce infection pressure within a vineyard.

When removing infected vines, it is important to remove as much of the root system as practical. Some virus vectors, particularly mealybugs, can survive on remnant vine roots and continue to act as a source of infection for replacement vines.

Following vine removal:

Monitor neighbouring vines for signs of infection
Manage mealybug and scale populations to reduce further spread
Remove as much of the infected vine and root system as practical
Source replacement vines from certified, virus-tested planting material

Diagnostic laboratories

Virus and phytoplasma testing services are available through:

Grapevine leafroll

Grapevine leafroll is one of the most widespread, economically important virus diseases affecting vineyards worldwide and is widespread in Australia.

The disease is associated with a group of grapevine leafroll-associated viruses (GLRaVs), particularly GLRaV-1 and GLRaV-3.

Why leafroll is important

Leafroll disease can significantly affect both yield and fruit quality.

Common impacts include:

Reduced vine growth and vigour
Smaller canopies
Delayed fruit ripening
Reduced sugar accumulation
Increased titratable acidity
Reduced colour development in red varieties
Reduced aroma development
Lower yields
Reduced vineyard longevity
Reduced propagation material quality

These effects can be particularly challenging in cooler wine regions where delayed ripening may push harvest dates later into the season.

Recognising leafroll symptoms

Symptoms typically become most obvious from late summer through autumn.

Red varieties

Look for:

Reddening between leaf veins
Green veins remaining clearly visible
Downward rolling of leaves

White varieties

Look for:

Yellowing between leaf veins
Downward rolling of leaves
Reduced symptom visibility compared with red varieties

Symptom severity varies between cultivars and growing conditions. Some infected vines and rootstocks may remain symptomless despite infection, making laboratory testing important where disease is suspected.

Transmission and spread

Leafroll viruses spread primarily through:

Vegetative propagation
Grafting
Mealybugs
Scale insects

Research has shown that leafroll viruses spread within Australian vineyards via mealybugs and scale insects. As these vectors move between vines, infections often develop in clusters along vineyard rows. Managing vector populations is therefore an important part of limiting virus spread within vineyards.

Management priorities

Start with certified virus-tested planting material.
Monitor vineyards regularly for symptoms.
Test suspect vines to confirm infection.
Manage mealybug and scale populations.
Remove infected vines where practical, taking care to remove as much remnant root material as possible.
Monitor surrounding vines closely for several seasons for new infections.
Test vines before top-working or using propagation material.

Shiraz disease

Shiraz disease is one of Australia's most serious virus-related vine disorders and has primarily been reported in Australia and South Africa.

The disease is strongly associated with grapevine virus A (GVA) and is frequently linked with mixed infections involving grapevine leafroll-associated viruses, particularly GLRaV-3.

Why growers should be concerned

Affected vines can experience:

Poor spring growth
Delayed budburst
Poor spring growth
Reduced vigour
Delayed cane maturation
Significant yield loss
Reduced fruit quality
Progressive vineyard decline

The financial consequences can be substantial, especially in premium Shiraz vineyards where fruit quality directly influences grape price.

What to look for

Symptoms may include:

Poor or delayed budburst
Restricted spring growth
Delayed vine development
Reduced cropping levels
Leafroll-like symptoms
Retention of affected leaves into winter
Delayed cane maturity with patches of green tissue remaining on canes late in the season

Because symptoms can overlap with other disorders, laboratory testing is essential for accurate diagnosis.

Reducing risk

Growers should:

Source certified, virus-tested planting material
Test vines before top-working
Monitor and manage for mealybugs and scale insect populations
Remove confirmed infected vines where practical
Avoid using potentially infected propagation material

Rugose wood diseases

The rugose wood complex includes five virus-associated diseases:

Rupestris stem pitting
Kober stem grooving
Corky bark
LN33 stem grooving
Corky wood

Although widespread, the impact of rugose wood diseases varies depending on the variety, rootstock and virus involved.

Vineyard impacts

Rugose wood diseases can cause:

Delayed budburst
Reduced vine vigour
Declining productivity
Reduced cane growth
Poor propagation material quality
Vine decline and death
Reduced vineyard lifespan

Yield losses can be significant in some virus-host combinations.

What growers should look for

Symptoms are often hidden beneath bark tissue and may include:

Swelling around graft unions
Pitting or grooving of wood
Uneven scion and rootstock growth
Graft incompatibility
Reduced canopy development

Many infected vines do not display obvious foliar symptoms, making testing essential.

Management considerations

Because rugose wood symptoms can be difficult to identify visually:

Use certified planting material
Test suspect vines
Monitor for mealybug and scale vectors
Test plant material before propagation or top-working
Remove infected vines where appropriate

Other grapevine viruses

Several other grapevine viruses occur in Australia or have been detected through increased testing and surveillance. While their impacts vary, the same core management principles apply: use certified virus-tested planting material, monitor vineyards regularly and confirm infections through laboratory testing.

Grapevine berry inner necrosis virus (GINV)

Grapevine berry inner necrosis virus (GINV) has been detected in Australian wine grapes, table grapes and rootstocks. While the virus has been associated with symptoms including delayed budburst, leaf abnormalities and reduced vine vigour overseas, its significance under Australian vineyard conditions remains uncertain.

Not all infected vines develop symptoms, making visual diagnosis unreliable. GINV is thought to spread through infected propagation material and grape bud mites. Laboratory testing is required to confirm infection and distinguish GINV from other vine disorders that may cause similar symptoms.

Grapevine Pinot gris virus (GPGV)

Grapevine Pinot gris virus (GPGV) has been detected in Australia and can occur in both symptomatic and symptomless vines. Overseas, the virus has been associated with delayed budburst, leaf distortion, reduced shoot growth and lower yields, although symptom severity can vary between vineyards, varieties and seasons.

GPGV is thought to spread through infected propagation material and bud or blister mites. Because many infected vines remain symptomless and symptoms can resemble other disorders, laboratory testing is required to confirm infection.

Grapevine red blotch virus (GRBV)

Grapevine red blotch virus (GRBV) has been detected in Australia through routine testing programs. While the virus has been associated with delayed ripening and reduced fruit quality overseas, its significance under Australian conditions remains uncertain.

Symptoms can resemble grapevine leafroll disease and other vine disorders, making laboratory testing necessary for confirmation. The virus is known to spread through infected propagation material, while the importance of insect vectors under Australian conditions remains uncertain.