Eutypa dieback and grapevine trunk disease

Why eutypa matters

Unlike many vineyard diseases, eutypa is often a hidden threat. Infections typically occur through pruning wounds, but symptoms may not appear for three to eight years. By the time vines show visible signs of decline, significant internal wood damage has often already occurred. This means preventative management, careful pruning practices and regular monitoring are essential components of long-term vineyard performance.

For grape growers, eutypa management is not simply a disease control issue. It is a vineyard asset management decision that influences yields, labour requirements, reworking costs, fruit uniformity and the productive lifespan of a block. Research has shown that yield losses can exceed 1.5 t/ha in severely affected vineyards, while symptoms such as uneven ripening can also compromise wine quality

Understanding the disease cycle

Eutypa spores are released from infected dead wood during and after rainfall events and can be spread considerable distances by wind. Infected dead wood within vineyards, and in nearby perennial hosts such as stone fruit and other woody crops, can contribute to local spore levels. Spores infect fresh pruning wounds, with the highest risk occurring during the first two weeks after pruning, although wounds may remain susceptible for up to six weeks. 

Once inside the vine, the fungus slowly colonises woody tissue, restricting the movement of water and nutrients and progressively killing productive vine structures.

The disease advances slowly through the vine, meaning infections acquired early in a vineyard's life may not become visible until many years later. This is why protecting pruning wounds every year, from the first pruning season onwards is considered one of the most cost-effective disease management practices available.

Recognising eutypa in the vineyard

The best time to identify eutypa symptoms is during spring when shoots are approximately 30 to 70 cm long. At this stage, healthy shoots have begun to grow strongly while affected shoots remain stunted, creating clear visual contrast.

Common symptoms include:

• Stunted shoots and shortened internodes
• Yellowing leaves with cupped or distorted margins
• Tattered or necrotic leaf edges
• Dead spurs and declining cordons
• Uneven bunch ripening and reduced bunch size
• Wedge-shaped brown staining inside cordons and trunks
• Trunk cankers and eventual vine death

Which varieties are most affected?

All grapevine varieties can become infected, but symptom expression varies. Australian observations have found more severe impacts in Shiraz, Cabernet Sauvignon and Sauvignon Blanc, while Riesling and Merlot generally show lower levels of visible symptoms.

Older vineyards are particularly vulnerable because they contain more pruning wounds and have experienced multiple years of exposure to infection events. Surveys have found that some vineyards can reach more than 80% incidence of symptoms by 15 to 20 years of age if disease pressure is not managed.

Best practice prevention and wound protection

Because infection occurs primarily through pruning wounds, vineyard operations have a direct influence on disease risk.

Key recommendations

• Avoid pruning immediately before, during or after rain events.
• Consider late winter pruning when wound healing is more rapid.
• Use double pruning where feasible, particularly in higher-risk vineyards.
• Make smaller, well-positioned pruning cuts wherever possible.
• Avoid creating large wounds near the trunk when alternatives are available.
• Remove infected wood from the vineyard and destroy it through burning or burial.
• Apply registered wound protection products to pruning wounds or remedial surgery cuts as soon as possible after they are made, ideally within 24 hours.

Recent Australian research has also shown that retaining pruning stubs or base buds can reduce Eutypa lata infection compared with flush pruning cuts. This "respectful pruning" approach may help reduce wound size and limit pathogen movement through the vine, making it a valuable addition to integrated trunk disease management strategies.

Monitoring and decision making

Regular vineyard surveys allow growers to understand the extent and severity of trunk disease within blocks and prioritise management investment. Because eutypa symptoms can sometimes be confused with herbicide damage, frost, salt toxicity, earwig feeding or bud mite damage, assessing wood symptoms and confirming diagnosis is an important step before undertaking major remediation activities.  

The best practice guide recommends assessing at least 200 representative vines during spring and evaluating either:

1. Disease incidence (presence or absence of symptoms), or
2. Disease severity (proportion of productive cordon lost).

Growers can simplify this process using the Grape Assess smartphone app, which enables vineyard assessments to be recorded in the field and exported with GPS coordinates to support targeted management decisions.

Reworking versus replanting

Remedial surgery involves removing all infected wood plus a margin of healthy tissue (at least 10cm) and retraining the vine from healthy shoots growing below the infection. Following surgery, wounds should be protected with a registered wound protection product to minimise the risk of reinfection.  Depending on the extent of disease and vine response, vineyards can often return to full production within two to three years.

In some own-rooted vineyards, layering may provide an alternative to replanting while retaining an established root system. This approach utilises the mature root system of the parent vine, which can improve establishment in mature vineyards.

The best management option depends on:

• Variety performance and value
• Vineyard age
• Disease incidence and severity
• Cost of remediation
• Labour availability
• Long-term vineyard plans

Lessons from Australian vineyards

Several South Australian vineyards have successfully extended vineyard life through proactive eutypa management.

Taylors Wines implemented a staged trunk renewal program across 90 hectares of Shiraz after disease reduced yields by up to 60% in affected blocks. The vineyard adopted trunk renewal approximately 30 cm above ground level, followed by retraining from watershoots. The program restored normal production within three years while costing substantially less than full vineyard replanting.

Chapel Hill Winery shifted from repeated arm replacement to more intensive trunk reworking after declining yields affected vineyard profitability. By combining trunk renewal, retraining and wound protection, the vineyard was able to rapidly restore production while retaining existing trellis and irrigation infrastructure.

These examples demonstrate that early intervention generally provides better outcomes than waiting until disease impacts become severe. Growers who monitor regularly and act before significant cordon or trunk decline occurs are often able to preserve vineyard value and maintain production continuity.

Case studies

Barossa experiences

Viticulturists and vineyard owners from the Barossa discussed their experiences in the below series of case studies and videos developed by the SA North Regional Program

Clare Valley experiences

Supported through the Wine Australia Regional Program for SA North, Clare Valley Wine and Grape Association developed the below video series exploring methods from identification and monitoring to reworking and prevention of infection.

With support from Wine Australia, Clare Valley Wine and Grape Association developed the below series of case studies exploring local experiences managing eutypa-affected vines. 

References

• Best practice management guide: Grapevine trunk disease
• Eutypa dieback factsheet 1
• Eutypa dieback factsheet 2
• Eutypa dieback factsheet 3
• Eutypa dieback factsheet 4